https://openjdk.java.net/ 
/*
 * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * questions.
 */

package java.util.jar;

import jdk.internal.misc.SharedSecrets;
import jdk.internal.misc.JavaUtilZipFileAccess;
import sun.security.action.GetPropertyAction;
import sun.security.util.ManifestEntryVerifier;
import sun.security.util.SignatureFileVerifier;

import java.io.ByteArrayInputStream;
import java.io.EOFException;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.lang.ref.SoftReference;
import java.net.URL;
import java.security.CodeSigner;
import java.security.CodeSource;
import java.security.cert.Certificate;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import java.util.Locale;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.function.Function;
import java.util.stream.Stream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipException;
import java.util.zip.ZipFile;


The JarFile class is used to read the contents of a jar file from any file that can be opened with java.io.RandomAccessFile. It extends the class java.util.zip.ZipFile with support for reading an optional Manifest entry, and support for processing multi-release jar files. The Manifest can be used to specify meta-information about the jar file and its entries. 
A multi-release jar file is a jar file that contains a manifest with a main attribute named "Multi-Release", a set of "base" entries, some of which are public classes with public or protected methods that comprise the public interface of the jar file, and a set of "versioned" entries contained in subdirectories of the "META-INF/versions" directory. The versioned entries are partitioned by the major version of the Java platform. A versioned entry, with a version n, 8 < n, in the "META-INF/versions/{n}" directory overrides the base entry as well as any entry with a version number i where 8 < i < n. 
By default, a JarFile for a multi-release jar file is configured to process the multi-release jar file as if it were a plain (unversioned) jar file, and as such an entry name is associated with at most one base entry. The JarFile may be configured to process a multi-release jar file by creating the JarFile with the JarFile(File, boolean, int, Version) constructor. The Runtime.Version object sets a maximum version used when searching for versioned entries. When so configured, an entry name can correspond with at most one base entry and zero or more versioned entries. A search is required to associate the entry name with the latest versioned entry whose version is less than or equal to the maximum version (see getEntry(String)). 
Class loaders that utilize JarFile to load classes from the contents of JarFile entries should construct the JarFile by invoking the JarFile(File, boolean, int, Version) constructor with the value Runtime.version() assigned to the last argument. This assures that classes compatible with the major version of the running JVM are loaded from multi-release jar files. 
 If the verify flag is on when opening a signed jar file, the content of the jar entry is verified against the signature embedded inside the manifest that is associated with its path name. For a multi-release jar file, the content of a versioned entry is verfieid against its own signature and JarEntry.getCodeSigners() returns its own signers. Please note that the verification process does not include validating the signer's certificate. A caller should inspect the return value of JarEntry.getCodeSigners() to further determine if the signature can be trusted. 
 Unless otherwise noted, passing a null argument to a constructor or method in this class will cause a NullPointerException to be thrown. 
Author: David Connelly
See Also:
Implementation Note:

 If the API can not be used to configure a JarFile (e.g. to override the configuration of a compiled application or library), two System properties are available. 
    

  •  jdk.util.jar.version can be assigned a value that is the String representation of a non-negative integer <= Runtime.version().feature(). The value is used to set the effective runtime version to something other than the default value obtained by evaluating Runtime.version().feature(). The effective runtime version is the version that the JarFile(File, boolean, int, Version) constructor uses when the value of the last argument is JarFile.runtimeVersion(). 
    • 

  •  jdk.util.jar.enableMultiRelease can be assigned one of the three String values true, false, or force.  The
value true, the default value, enables multi-release jar file
processing.  The value false disables multi-release jar processing, ignoring the "Multi-Release" manifest attribute, and the versioned directories in a multi-release jar file if they exist. Furthermore, the method isMultiRelease() returns false. The value
force causes the JarFile to be initialized to runtime versioning after construction. It effectively does the same as this code: (new JarFile(File, boolean, int, JarFile.runtimeVersion()). 
    • 



Since:  1.2
/**
 * The {@code JarFile} class is used to read the contents of a jar file
 * from any file that can be opened with {@code java.io.RandomAccessFile}.
 * It extends the class {@code java.util.zip.ZipFile} with support
 * for reading an optional {@code Manifest} entry, and support for
 * processing multi-release jar files.  The {@code Manifest} can be used
 * to specify meta-information about the jar file and its entries.
 *
 * <p><a id="multirelease">A multi-release jar file</a> is a jar file that
 * contains a manifest with a main attribute named "Multi-Release",
 * a set of "base" entries, some of which are public classes with public
 * or protected methods that comprise the public interface of the jar file,
 * and a set of "versioned" entries contained in subdirectories of the
 * "META-INF/versions" directory.  The versioned entries are partitioned by the
 * major version of the Java platform.  A versioned entry, with a version
 * {@code n}, {@code 8 < n}, in the "META-INF/versions/{n}" directory overrides
 * the base entry as well as any entry with a version number {@code i} where
 * {@code 8 < i < n}.
 *
 * <p>By default, a {@code JarFile} for a multi-release jar file is configured
 * to process the multi-release jar file as if it were a plain (unversioned) jar
 * file, and as such an entry name is associated with at most one base entry.
 * The {@code JarFile} may be configured to process a multi-release jar file by
 * creating the {@code JarFile} with the
 * {@link JarFile#JarFile(File, boolean, int, Runtime.Version)} constructor.  The
 * {@code Runtime.Version} object sets a maximum version used when searching for
 * versioned entries.  When so configured, an entry name
 * can correspond with at most one base entry and zero or more versioned
 * entries. A search is required to associate the entry name with the latest
 * versioned entry whose version is less than or equal to the maximum version
 * (see {@link #getEntry(String)}).
 *
 * <p>Class loaders that utilize {@code JarFile} to load classes from the
 * contents of {@code JarFile} entries should construct the {@code JarFile}
 * by invoking the {@link JarFile#JarFile(File, boolean, int, Runtime.Version)}
 * constructor with the value {@code Runtime.version()} assigned to the last
 * argument.  This assures that classes compatible with the major
 * version of the running JVM are loaded from multi-release jar files.
 *
 * <p> If the {@code verify} flag is on when opening a signed jar file, the content
 * of the jar entry is verified against the signature embedded inside the manifest
 * that is associated with its {@link JarEntry#getRealName() path name}. For a
 * multi-release jar file, the content of a versioned entry is verfieid against
 * its own signature and {@link JarEntry#getCodeSigners()} returns its own signers.
 *
 * Please note that the verification process does not include validating the
 * signer's certificate. A caller should inspect the return value of
 * {@link JarEntry#getCodeSigners()} to further determine if the signature
 * can be trusted.
 *
 * <p> Unless otherwise noted, passing a {@code null} argument to a constructor
 * or method in this class will cause a {@link NullPointerException} to be
 * thrown.
 *
 * @implNote
 * <div class="block">
 * If the API can not be used to configure a {@code JarFile} (e.g. to override
 * the configuration of a compiled application or library), two {@code System}
 * properties are available.
 * <ul>
 * <li>
 * {@code jdk.util.jar.version} can be assigned a value that is the
 * {@code String} representation of a non-negative integer
 * {@code <= Runtime.version().feature()}.  The value is used to set the effective
 * runtime version to something other than the default value obtained by
 * evaluating {@code Runtime.version().feature()}. The effective runtime version
 * is the version that the {@link JarFile#JarFile(File, boolean, int, Runtime.Version)}
 * constructor uses when the value of the last argument is
 * {@code JarFile.runtimeVersion()}.
 * </li>
 * <li>
 * {@code jdk.util.jar.enableMultiRelease} can be assigned one of the three
 * {@code String} values <em>true</em>, <em>false</em>, or <em>force</em>.  The
 * value <em>true</em>, the default value, enables multi-release jar file
 * processing.  The value <em>false</em> disables multi-release jar processing,
 * ignoring the "Multi-Release" manifest attribute, and the versioned
 * directories in a multi-release jar file if they exist.  Furthermore,
 * the method {@link JarFile#isMultiRelease()} returns <em>false</em>. The value
 * <em>force</em> causes the {@code JarFile} to be initialized to runtime
 * versioning after construction.  It effectively does the same as this code:
 * {@code (new JarFile(File, boolean, int, JarFile.runtimeVersion())}.
 * </li>
 * </ul>
 * </div>
 *
 * @author  David Connelly
 * @see     Manifest
 * @see     java.util.zip.ZipFile
 * @see     java.util.jar.JarEntry
 * @since   1.2
 */
public
class JarFile extends ZipFile {
    private static final Runtime.Version BASE_VERSION;
    private static final int BASE_VERSION_FEATURE;
    private static final Runtime.Version RUNTIME_VERSION;
    private static final boolean MULTI_RELEASE_ENABLED;
    private static final boolean MULTI_RELEASE_FORCED;
    private static final ThreadLocal<Boolean> isInitializing = new ThreadLocal<>();

    private SoftReference<Manifest> manRef;
    private JarEntry manEntry;
    private JarVerifier jv;
    private boolean jvInitialized;
    private boolean verify;
    private final Runtime.Version version;  // current version
    private final int versionFeature;       // version.feature()
    private boolean isMultiRelease;         // is jar multi-release?

    // indicates if Class-Path attribute present
    private boolean hasClassPathAttribute;
    // true if manifest checked for special attributes
    private volatile boolean hasCheckedSpecialAttributes;

    private static final JavaUtilZipFileAccess JUZFA;

    static {
        // Set up JavaUtilJarAccess in SharedSecrets
        SharedSecrets.setJavaUtilJarAccess(new JavaUtilJarAccessImpl());
        // Get JavaUtilZipFileAccess from SharedSecrets
        JUZFA = jdk.internal.misc.SharedSecrets.getJavaUtilZipFileAccess();
        // multi-release jar file versions >= 9
        BASE_VERSION = Runtime.Version.parse(Integer.toString(8));
        BASE_VERSION_FEATURE = BASE_VERSION.feature();
        String jarVersion = GetPropertyAction.privilegedGetProperty("jdk.util.jar.version");
        int runtimeVersion = Runtime.version().feature();
        if (jarVersion != null) {
            int jarVer = Integer.parseInt(jarVersion);
            runtimeVersion = (jarVer > runtimeVersion)
                    ? runtimeVersion
                    : Math.max(jarVer, BASE_VERSION_FEATURE);
        }
        RUNTIME_VERSION = Runtime.Version.parse(Integer.toString(runtimeVersion));
        String enableMultiRelease = GetPropertyAction
                .privilegedGetProperty("jdk.util.jar.enableMultiRelease", "true");
        switch (enableMultiRelease) {
            case "true":
            default:
                MULTI_RELEASE_ENABLED = true;
                MULTI_RELEASE_FORCED = false;
                break;
            case "false":
                MULTI_RELEASE_ENABLED = false;
                MULTI_RELEASE_FORCED = false;
                break;
            case "force":
                MULTI_RELEASE_ENABLED = true;
                MULTI_RELEASE_FORCED = true;
                break;
        }
    }

    private static final String META_INF = "META-INF/";

    private static final String META_INF_VERSIONS = META_INF + "versions/";

    
The JAR manifest file name.

/**
     * The JAR manifest file name.
     */
    public static final String MANIFEST_NAME = META_INF + "MANIFEST.MF";

    
Returns the version that represents the unversioned configuration of a
multi-release jar file.

Returns:the version that represents the unversioned configuration
Since:9
/**
     * Returns the version that represents the unversioned configuration of a
     * multi-release jar file.
     *
     * @return the version that represents the unversioned configuration
     *
     * @since 9
     */
    public static Runtime.Version baseVersion() {
        return BASE_VERSION;
    }

    
Returns the version that represents the effective runtime versioned
configuration of a multi-release jar file.

 By default the feature version number of the returned Version will be equal to the feature version number of Runtime.version(). However, if the jdk.util.jar.version property is set, the returned Version is derived from that property and feature version numbers may not be equal. 
Returns:the version that represents the runtime versioned configuration
Since:9
/**
     * Returns the version that represents the effective runtime versioned
     * configuration of a multi-release jar file.
     * <p>
     * By default the feature version number of the returned {@code Version} will
     * be equal to the feature version number of {@code Runtime.version()}.
     * However, if the {@code jdk.util.jar.version} property is set, the
     * returned {@code Version} is derived from that property and feature version
     * numbers may not be equal.
     *
     * @return the version that represents the runtime versioned configuration
     *
     * @since 9
     */
    public static Runtime.Version runtimeVersion() {
        return RUNTIME_VERSION;
    }

    
Creates a new JarFile to read from the specified file name. The JarFile will be verified if it is signed. 
Params:
  • name – the name of the jar file to be opened for reading
Throws:
/**
     * Creates a new {@code JarFile} to read from the specified
     * file {@code name}. The {@code JarFile} will be verified if
     * it is signed.
     * @param name the name of the jar file to be opened for reading
     * @throws IOException if an I/O error has occurred
     * @throws SecurityException if access to the file is denied
     *         by the SecurityManager
     */
    public JarFile(String name) throws IOException {
        this(new File(name), true, ZipFile.OPEN_READ);
    }

    
Creates a new JarFile to read from the specified file name. 
Params:
  • name – the name of the jar file to be opened for reading
  • verify – whether or not to verify the jar file if
it is signed.
Throws:
/**
     * Creates a new {@code JarFile} to read from the specified
     * file {@code name}.
     * @param name the name of the jar file to be opened for reading
     * @param verify whether or not to verify the jar file if
     * it is signed.
     * @throws IOException if an I/O error has occurred
     * @throws SecurityException if access to the file is denied
     *         by the SecurityManager
     */
    public JarFile(String name, boolean verify) throws IOException {
        this(new File(name), verify, ZipFile.OPEN_READ);
    }

    
Creates a new JarFile to read from the specified File object. The JarFile will be verified if it is signed. 
Params:
  • file – the jar file to be opened for reading
Throws:
/**
     * Creates a new {@code JarFile} to read from the specified
     * {@code File} object. The {@code JarFile} will be verified if
     * it is signed.
     * @param file the jar file to be opened for reading
     * @throws IOException if an I/O error has occurred
     * @throws SecurityException if access to the file is denied
     *         by the SecurityManager
     */
    public JarFile(File file) throws IOException {
        this(file, true, ZipFile.OPEN_READ);
    }

    
Creates a new JarFile to read from the specified File object. 
Params:
  • file – the jar file to be opened for reading
  • verify – whether or not to verify the jar file if
it is signed.
Throws:
/**
     * Creates a new {@code JarFile} to read from the specified
     * {@code File} object.
     * @param file the jar file to be opened for reading
     * @param verify whether or not to verify the jar file if
     * it is signed.
     * @throws IOException if an I/O error has occurred
     * @throws SecurityException if access to the file is denied
     *         by the SecurityManager.
     */
    public JarFile(File file, boolean verify) throws IOException {
        this(file, verify, ZipFile.OPEN_READ);
    }

    
Creates a new JarFile to read from the specified File object in the specified mode. The mode argument must be either OPEN_READ or OPEN_READ | OPEN_DELETE. 
Params:
  • file – the jar file to be opened for reading
  • verify – whether or not to verify the jar file if
it is signed.
  • mode – the mode in which the file is to be opened
Throws:
Since:1.3
/**
     * Creates a new {@code JarFile} to read from the specified
     * {@code File} object in the specified mode.  The mode argument
     * must be either {@code OPEN_READ} or {@code OPEN_READ | OPEN_DELETE}.
     *
     * @param file the jar file to be opened for reading
     * @param verify whether or not to verify the jar file if
     * it is signed.
     * @param mode the mode in which the file is to be opened
     * @throws IOException if an I/O error has occurred
     * @throws IllegalArgumentException
     *         if the {@code mode} argument is invalid
     * @throws SecurityException if access to the file is denied
     *         by the SecurityManager
     * @since 1.3
     */
    public JarFile(File file, boolean verify, int mode) throws IOException {
        this(file, verify, mode, BASE_VERSION);
    }

    
Creates a new JarFile to read from the specified File object in the specified mode. The mode argument must be either OPEN_READ or OPEN_READ | OPEN_DELETE. The version argument, after being converted to a canonical form, is used to configure the JarFile for processing multi-release jar files. 
 The canonical form derived from the version parameter is Runtime.Version.parse(Integer.toString(n)) where n is Math.max(version.feature(), JarFile.baseVersion().feature()). 
Params:
  • file – the jar file to be opened for reading
  • verify – whether or not to verify the jar file if
it is signed.
  • mode – the mode in which the file is to be opened
  • version – specifies the release version for a multi-release jar file
Throws:
Since:9
/**
     * Creates a new {@code JarFile} to read from the specified
     * {@code File} object in the specified mode.  The mode argument
     * must be either {@code OPEN_READ} or {@code OPEN_READ | OPEN_DELETE}.
     * The version argument, after being converted to a canonical form, is
     * used to configure the {@code JarFile} for processing
     * multi-release jar files.
     * <p>
     * The canonical form derived from the version parameter is
     * {@code Runtime.Version.parse(Integer.toString(n))} where {@code n} is
     * {@code Math.max(version.feature(), JarFile.baseVersion().feature())}.
     *
     * @param file the jar file to be opened for reading
     * @param verify whether or not to verify the jar file if
     * it is signed.
     * @param mode the mode in which the file is to be opened
     * @param version specifies the release version for a multi-release jar file
     * @throws IOException if an I/O error has occurred
     * @throws IllegalArgumentException
     *         if the {@code mode} argument is invalid
     * @throws SecurityException if access to the file is denied
     *         by the SecurityManager
     * @throws NullPointerException if {@code version} is {@code null}
     * @since 9
     */
    public JarFile(File file, boolean verify, int mode, Runtime.Version version) throws IOException {
        super(file, mode);
        this.verify = verify;
        Objects.requireNonNull(version);
        if (MULTI_RELEASE_FORCED || version.feature() == RUNTIME_VERSION.feature()) {
            // This deals with the common case where the value from JarFile.runtimeVersion() is passed
            this.version = RUNTIME_VERSION;
        } else if (version.feature() <= BASE_VERSION_FEATURE) {
            // This also deals with the common case where the value from JarFile.baseVersion() is passed
            this.version = BASE_VERSION;
        } else {
            // Canonicalize
            this.version = Runtime.Version.parse(Integer.toString(version.feature()));
        }
        this.versionFeature = this.version.feature();
    }

    
Returns the maximum version used when searching for versioned entries.

 If this JarFile is not a multi-release jar file or is not configured to be processed as such, then the version returned will be the same as that returned from baseVersion(). 
Returns:the maximum version
Since:9
/**
     * Returns the maximum version used when searching for versioned entries.
     * <p>
     * If this {@code JarFile} is not a multi-release jar file or is not
     * configured to be processed as such, then the version returned will be the
     * same as that returned from {@link #baseVersion()}.
     *
     * @return the maximum version
     * @since 9
     */
    public final Runtime.Version getVersion() {
        return isMultiRelease() ? this.version : BASE_VERSION;
    }

    
Indicates whether or not this jar file is a multi-release jar file.

Returns:true if this JarFile is a multi-release jar file
Since:9
/**
     * Indicates whether or not this jar file is a multi-release jar file.
     *
     * @return true if this JarFile is a multi-release jar file
     * @since 9
     */
    public final boolean isMultiRelease() {
        if (isMultiRelease) {
            return true;
        }
        if (MULTI_RELEASE_ENABLED) {
            try {
                checkForSpecialAttributes();
            } catch (IOException io) {
                isMultiRelease = false;
            }
        }
        return isMultiRelease;
    }

    
Returns the jar file manifest, or null if none. 
Throws:
Returns:the jar file manifest, or null if none
/**
     * Returns the jar file manifest, or {@code null} if none.
     *
     * @return the jar file manifest, or {@code null} if none
     *
     * @throws IllegalStateException
     *         may be thrown if the jar file has been closed
     * @throws IOException  if an I/O error has occurred
     */
    public Manifest getManifest() throws IOException {
        return getManifestFromReference();
    }

    private Manifest getManifestFromReference() throws IOException {
        Manifest man = manRef != null ? manRef.get() : null;

        if (man == null) {

            JarEntry manEntry = getManEntry();

            // If found then load the manifest
            if (manEntry != null) {
                if (verify) {
                    byte[] b = getBytes(manEntry);
                    if (!jvInitialized) {
                        jv = new JarVerifier(b);
                    }
                    man = new Manifest(jv, new ByteArrayInputStream(b));
                } else {
                    man = new Manifest(super.getInputStream(manEntry));
                }
                manRef = new SoftReference<>(man);
            }
        }
        return man;
    }

    private String[] getMetaInfEntryNames() {
        return JUZFA.getMetaInfEntryNames((ZipFile)this);
    }

    
Returns the JarEntry for the given base entry name or null if not found. 
If this JarFile is a multi-release jar file and is configured to be processed as such, then a search is performed to find and return a JarEntry that is the latest versioned entry associated with the given entry name. The returned JarEntry is the versioned entry corresponding to the given base entry name prefixed with the string "META-INF/versions/{n}/", for the largest value of n for which an entry exists. If such a versioned entry does not exist, then the JarEntry for the base entry is returned, otherwise null is returned if no entries are found. The initial value for the version n is the maximum version as returned by the method getVersion(). 
Params:
  • name – the jar file entry name
Throws:
See Also:
Returns:the JarEntry for the given entry name, or the versioned entry name, or null if not found
Implementation Requirements:

 This implementation invokes getEntry(String). 
/**
     * Returns the {@code JarEntry} for the given base entry name or
     * {@code null} if not found.
     *
     * <p>If this {@code JarFile} is a multi-release jar file and is configured
     * to be processed as such, then a search is performed to find and return
     * a {@code JarEntry} that is the latest versioned entry associated with the
     * given entry name.  The returned {@code JarEntry} is the versioned entry
     * corresponding to the given base entry name prefixed with the string
     * {@code "META-INF/versions/{n}/"}, for the largest value of {@code n} for
     * which an entry exists.  If such a versioned entry does not exist, then
     * the {@code JarEntry} for the base entry is returned, otherwise
     * {@code null} is returned if no entries are found.  The initial value for
     * the version {@code n} is the maximum version as returned by the method
     * {@link JarFile#getVersion()}.
     *
     * @param name the jar file entry name
     * @return the {@code JarEntry} for the given entry name, or
     *         the versioned entry name, or {@code null} if not found
     *
     * @throws IllegalStateException
     *         may be thrown if the jar file has been closed
     *
     * @see java.util.jar.JarEntry
     *
     * @implSpec
     * <div class="block">
     * This implementation invokes {@link JarFile#getEntry(String)}.
     * </div>
     */
    public JarEntry getJarEntry(String name) {
        return (JarEntry)getEntry(name);
    }

    
Returns the ZipEntry for the given base entry name or null if not found. 
If this JarFile is a multi-release jar file and is configured to be processed as such, then a search is performed to find and return a ZipEntry that is the latest versioned entry associated with the given entry name. The returned ZipEntry is the versioned entry corresponding to the given base entry name prefixed with the string "META-INF/versions/{n}/", for the largest value of n for which an entry exists. If such a versioned entry does not exist, then the ZipEntry for the base entry is returned, otherwise null is returned if no entries are found. The initial value for the version n is the maximum version as returned by the method getVersion(). 
Params:
  • name – the jar file entry name
Throws:
See Also:
Returns:the ZipEntry for the given entry name or the versioned entry name or null if not found
Implementation Requirements:

 This implementation may return a versioned entry for the requested name even if there is not a corresponding base entry. This can occur if there is a private or package-private versioned entry that matches. If a subclass overrides this method, assure that the override method invokes super.getEntry(name) to obtain all versioned entries. 
/**
     * Returns the {@code ZipEntry} for the given base entry name or
     * {@code null} if not found.
     *
     * <p>If this {@code JarFile} is a multi-release jar file and is configured
     * to be processed as such, then a search is performed to find and return
     * a {@code ZipEntry} that is the latest versioned entry associated with the
     * given entry name.  The returned {@code ZipEntry} is the versioned entry
     * corresponding to the given base entry name prefixed with the string
     * {@code "META-INF/versions/{n}/"}, for the largest value of {@code n} for
     * which an entry exists.  If such a versioned entry does not exist, then
     * the {@code ZipEntry} for the base entry is returned, otherwise
     * {@code null} is returned if no entries are found.  The initial value for
     * the version {@code n} is the maximum version as returned by the method
     * {@link JarFile#getVersion()}.
     *
     * @param name the jar file entry name
     * @return the {@code ZipEntry} for the given entry name or
     *         the versioned entry name or {@code null} if not found
     *
     * @throws IllegalStateException
     *         may be thrown if the jar file has been closed
     *
     * @see java.util.zip.ZipEntry
     *
     * @implSpec
     * <div class="block">
     * This implementation may return a versioned entry for the requested name
     * even if there is not a corresponding base entry.  This can occur
     * if there is a private or package-private versioned entry that matches.
     * If a subclass overrides this method, assure that the override method
     * invokes {@code super.getEntry(name)} to obtain all versioned entries.
     * </div>
     */
    public ZipEntry getEntry(String name) {
        JarFileEntry je = getEntry0(name);
        if (isMultiRelease()) {
            return getVersionedEntry(name, je);
        }
        return je;
    }

    
Returns an enumeration of the jar file entries.

Throws:
Returns:an enumeration of the jar file entries
/**
     * Returns an enumeration of the jar file entries.
     *
     * @return an enumeration of the jar file entries
     * @throws IllegalStateException
     *         may be thrown if the jar file has been closed
     */
    public Enumeration<JarEntry> entries() {
        return JUZFA.entries(this, JarFileEntry::new);
    }

    
Returns an ordered Stream over the jar file entries. Entries appear in the Stream in the order they appear in the central directory of the jar file. 
Throws:
Returns:an ordered Stream of entries in this jar file
Since:1.8
/**
     * Returns an ordered {@code Stream} over the jar file entries.
     * Entries appear in the {@code Stream} in the order they appear in
     * the central directory of the jar file.
     *
     * @return an ordered {@code Stream} of entries in this jar file
     * @throws IllegalStateException if the jar file has been closed
     * @since 1.8
     */
    public Stream<JarEntry> stream() {
        return JUZFA.stream(this, JarFileEntry::new);
    }

    
Returns a Stream of the versioned jar file entries. 
If this JarFile is a multi-release jar file and is configured to be processed as such, then an entry in the stream is the latest versioned entry associated with the corresponding base entry name. The maximum version of the latest versioned entry is the version returned by getVersion(). The returned stream may include an entry that only exists as a versioned entry. If the jar file is not a multi-release jar file or the JarFile is not configured for processing a multi-release jar file, this method returns the same stream that stream() returns. 
Returns:stream of versioned entries
Since:10
/**
     * Returns a {@code Stream} of the versioned jar file entries.
     *
     * <p>If this {@code JarFile} is a multi-release jar file and is configured to
     * be processed as such, then an entry in the stream is the latest versioned entry
     * associated with the corresponding base entry name. The maximum version of the
     * latest versioned entry is the version returned by {@link #getVersion()}.
     * The returned stream may include an entry that only exists as a versioned entry.
     *
     * If the jar file is not a multi-release jar file or the {@code JarFile} is not
     * configured for processing a multi-release jar file, this method returns the
     * same stream that {@link #stream()} returns.
     *
     * @return stream of versioned entries
     * @since 10
     */
    public Stream<JarEntry> versionedStream() {

        if (isMultiRelease()) {
            return JUZFA.entryNameStream(this).map(this::getBasename)
                                              .filter(Objects::nonNull)
                                              .distinct()
                                              .map(this::getJarEntry);
        }
        return stream();
    }

    /*
     * Invokes {@ZipFile}'s getEntry to Return a {@code JarFileEntry} for the
     * given entry name or {@code null} if not found.
     */
    private JarFileEntry getEntry0(String name) {
        // Not using a lambda/method reference here to optimize startup time
        Function<String, JarEntry> newJarFileEntryFn = new Function<>() {
            @Override
            public JarEntry apply(String name) {
                return new JarFileEntry(name);
            }
        };
        return (JarFileEntry)JUZFA.getEntry(this, name, newJarFileEntryFn);
    }

    private String getBasename(String name) {
        if (name.startsWith(META_INF_VERSIONS)) {
            int off = META_INF_VERSIONS.length();
            int index = name.indexOf('/', off);
            try {
                // filter out dir META-INF/versions/ and META-INF/versions/*/
                // and any entry with version > 'version'
                if (index == -1 || index == (name.length() - 1) ||
                    Integer.parseInt(name, off, index, 10) > versionFeature) {
                    return null;
                }
            } catch (NumberFormatException x) {
                return null; // remove malformed entries silently
            }
            // map to its base name
            return name.substring(index + 1);
        }
        return name;
    }

    private JarEntry getVersionedEntry(String name, JarEntry je) {
        if (BASE_VERSION_FEATURE < versionFeature) {
            if (!name.startsWith(META_INF)) {
                // search for versioned entry
                int v = versionFeature;
                while (v > BASE_VERSION_FEATURE) {
                    JarFileEntry vje = getEntry0(META_INF_VERSIONS + v + "/" + name);
                    if (vje != null) {
                        return vje.withBasename(name);
                    }
                    v--;
                }
            }
        }
        return je;
    }

    // placeholder for now
    String getRealName(JarEntry entry) {
        return entry.getRealName();
    }

    private class JarFileEntry extends JarEntry {
        private String basename;

        JarFileEntry(String name) {
            super(name);
            this.basename = name;
        }

        JarFileEntry(String name, ZipEntry vze) {
            super(vze);
            this.basename = name;
        }

        @Override
        public Attributes getAttributes() throws IOException {
            Manifest man = JarFile.this.getManifest();
            if (man != null) {
                return man.getAttributes(super.getName());
            } else {
                return null;
            }
        }

        @Override
        public Certificate[] getCertificates() {
            try {
                maybeInstantiateVerifier();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
            if (certs == null && jv != null) {
                certs = jv.getCerts(JarFile.this, realEntry());
            }
            return certs == null ? null : certs.clone();
        }

        @Override
        public CodeSigner[] getCodeSigners() {
            try {
                maybeInstantiateVerifier();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
            if (signers == null && jv != null) {
                signers = jv.getCodeSigners(JarFile.this, realEntry());
            }
            return signers == null ? null : signers.clone();
        }

        @Override
        public String getRealName() {
            return super.getName();
        }

        @Override
        public String getName() {
            return basename;
        }

        JarFileEntry realEntry() {
            if (isMultiRelease() && versionFeature != BASE_VERSION_FEATURE) {
                String entryName = super.getName();
                return entryName == basename || entryName.equals(basename) ?
                        this : new JarFileEntry(entryName, this);
            }
            return this;
        }

        // changes the basename, returns "this"
        JarFileEntry withBasename(String name) {
            basename = name;
            return this;
        }
    }

    /*
     * Ensures that the JarVerifier has been created if one is
     * necessary (i.e., the jar appears to be signed.) This is done as
     * a quick check to avoid processing of the manifest for unsigned
     * jars.
     */
    private void maybeInstantiateVerifier() throws IOException {
        if (jv != null) {
            return;
        }

        if (verify) {
            String[] names = getMetaInfEntryNames();
            if (names != null) {
                for (String nameLower : names) {
                    String name = nameLower.toUpperCase(Locale.ENGLISH);
                    if (name.endsWith(".DSA") ||
                        name.endsWith(".RSA") ||
                        name.endsWith(".EC") ||
                        name.endsWith(".SF")) {
                        // Assume since we found a signature-related file
                        // that the jar is signed and that we therefore
                        // need a JarVerifier and Manifest
                        getManifest();
                        return;
                    }
                }
            }
            // No signature-related files; don't instantiate a
            // verifier
            verify = false;
        }
    }

    /*
     * Initializes the verifier object by reading all the manifest
     * entries and passing them to the verifier.
     */
    private void initializeVerifier() {
        ManifestEntryVerifier mev = null;

        // Verify "META-INF/" entries...
        try {
            String[] names = getMetaInfEntryNames();
            if (names != null) {
                for (String name : names) {
                    String uname = name.toUpperCase(Locale.ENGLISH);
                    if (MANIFEST_NAME.equals(uname)
                            || SignatureFileVerifier.isBlockOrSF(uname)) {
                        JarEntry e = getJarEntry(name);
                        if (e == null) {
                            throw new JarException("corrupted jar file");
                        }
                        if (mev == null) {
                            mev = new ManifestEntryVerifier
                                (getManifestFromReference());
                        }
                        byte[] b = getBytes(e);
                        if (b != null && b.length > 0) {
                            jv.beginEntry(e, mev);
                            jv.update(b.length, b, 0, b.length, mev);
                            jv.update(-1, null, 0, 0, mev);
                        }
                    }
                }
            }
        } catch (IOException ex) {
            // if we had an error parsing any blocks, just
            // treat the jar file as being unsigned
            jv = null;
            verify = false;
            if (JarVerifier.debug != null) {
                JarVerifier.debug.println("jarfile parsing error!");
                ex.printStackTrace();
            }
        }

        // if after initializing the verifier we have nothing
        // signed, we null it out.

        if (jv != null) {

            jv.doneWithMeta();
            if (JarVerifier.debug != null) {
                JarVerifier.debug.println("done with meta!");
            }

            if (jv.nothingToVerify()) {
                if (JarVerifier.debug != null) {
                    JarVerifier.debug.println("nothing to verify!");
                }
                jv = null;
                verify = false;
            }
        }
    }

    /*
     * Reads all the bytes for a given entry. Used to process the
     * META-INF files.
     */
    private byte[] getBytes(ZipEntry ze) throws IOException {
        try (InputStream is = super.getInputStream(ze)) {
            int len = (int)ze.getSize();
            int bytesRead;
            byte[] b;
            // trust specified entry sizes when reasonably small
            if (len != -1 && len <= 65535) {
                b = new byte[len];
                bytesRead = is.readNBytes(b, 0, len);
            } else {
                b = is.readAllBytes();
                bytesRead = b.length;
            }
            if (len != -1 && len != bytesRead) {
                throw new EOFException("Expected:" + len + ", read:" + bytesRead);
            }
            return b;
        }
    }

    
Returns an input stream for reading the contents of the specified
zip file entry.

Params:
  • ze – the zip file entry
Throws:
Returns:an input stream for reading the contents of the specified
        zip file entry
/**
     * Returns an input stream for reading the contents of the specified
     * zip file entry.
     * @param ze the zip file entry
     * @return an input stream for reading the contents of the specified
     *         zip file entry
     * @throws ZipException if a zip file format error has occurred
     * @throws IOException if an I/O error has occurred
     * @throws SecurityException if any of the jar file entries
     *         are incorrectly signed.
     * @throws IllegalStateException
     *         may be thrown if the jar file has been closed
     */
    public synchronized InputStream getInputStream(ZipEntry ze)
        throws IOException
    {
        maybeInstantiateVerifier();
        if (jv == null) {
            return super.getInputStream(ze);
        }
        if (!jvInitialized) {
            initializeVerifier();
            jvInitialized = true;
            // could be set to null after a call to
            // initializeVerifier if we have nothing to
            // verify
            if (jv == null)
                return super.getInputStream(ze);
        }

        // wrap a verifier stream around the real stream
        return new JarVerifier.VerifierStream(
            getManifestFromReference(),
            verifiableEntry(ze),
            super.getInputStream(ze),
            jv);
    }

    private JarEntry verifiableEntry(ZipEntry ze) {
        if (ze instanceof JarFileEntry) {
            // assure the name and entry match for verification
            return ((JarFileEntry)ze).realEntry();
        }
        ze = getJarEntry(ze.getName());
        if (ze instanceof JarFileEntry) {
            return ((JarFileEntry)ze).realEntry();
        }
        return (JarEntry)ze;
    }

    // Statics for hand-coded Boyer-Moore search
    private static final byte[] CLASSPATH_CHARS =
            {'C','L','A','S','S','-','P','A','T','H', ':', ' '};

    // The bad character shift for "class-path: "
    private static final byte[] CLASSPATH_LASTOCC;

    // The good suffix shift for "class-path: "
    private static final byte[] CLASSPATH_OPTOSFT;

    private static final byte[] MULTIRELEASE_CHARS =
            {'M','U','L','T','I','-','R','E','L','E', 'A', 'S', 'E', ':',
                    ' ', 'T', 'R', 'U', 'E'};

    // The bad character shift for "multi-release: true"
    private static final byte[] MULTIRELEASE_LASTOCC;

    // The good suffix shift for "multi-release: true"
    private static final byte[] MULTIRELEASE_OPTOSFT;

    static {
        CLASSPATH_LASTOCC = new byte[65];
        CLASSPATH_OPTOSFT = new byte[12];
        CLASSPATH_LASTOCC[(int)'C' - 32] = 1;
        CLASSPATH_LASTOCC[(int)'L' - 32] = 2;
        CLASSPATH_LASTOCC[(int)'S' - 32] = 5;
        CLASSPATH_LASTOCC[(int)'-' - 32] = 6;
        CLASSPATH_LASTOCC[(int)'P' - 32] = 7;
        CLASSPATH_LASTOCC[(int)'A' - 32] = 8;
        CLASSPATH_LASTOCC[(int)'T' - 32] = 9;
        CLASSPATH_LASTOCC[(int)'H' - 32] = 10;
        CLASSPATH_LASTOCC[(int)':' - 32] = 11;
        CLASSPATH_LASTOCC[(int)' ' - 32] = 12;
        for (int i = 0; i < 11; i++) {
            CLASSPATH_OPTOSFT[i] = 12;
        }
        CLASSPATH_OPTOSFT[11] = 1;

        MULTIRELEASE_LASTOCC = new byte[65];
        MULTIRELEASE_OPTOSFT = new byte[19];
        MULTIRELEASE_LASTOCC[(int)'M' - 32] = 1;
        MULTIRELEASE_LASTOCC[(int)'I' - 32] = 5;
        MULTIRELEASE_LASTOCC[(int)'-' - 32] = 6;
        MULTIRELEASE_LASTOCC[(int)'L' - 32] = 9;
        MULTIRELEASE_LASTOCC[(int)'A' - 32] = 11;
        MULTIRELEASE_LASTOCC[(int)'S' - 32] = 12;
        MULTIRELEASE_LASTOCC[(int)':' - 32] = 14;
        MULTIRELEASE_LASTOCC[(int)' ' - 32] = 15;
        MULTIRELEASE_LASTOCC[(int)'T' - 32] = 16;
        MULTIRELEASE_LASTOCC[(int)'R' - 32] = 17;
        MULTIRELEASE_LASTOCC[(int)'U' - 32] = 18;
        MULTIRELEASE_LASTOCC[(int)'E' - 32] = 19;
        for (int i = 0; i < 17; i++) {
            MULTIRELEASE_OPTOSFT[i] = 19;
        }
        MULTIRELEASE_OPTOSFT[17] = 6;
        MULTIRELEASE_OPTOSFT[18] = 1;
    }

    private JarEntry getManEntry() {
        if (manEntry == null) {
            // First look up manifest entry using standard name
            JarEntry manEntry = getEntry0(MANIFEST_NAME);
            if (manEntry == null) {
                // If not found, then iterate through all the "META-INF/"
                // entries to find a match.
                String[] names = getMetaInfEntryNames();
                if (names != null) {
                    for (String name : names) {
                        if (MANIFEST_NAME.equals(name.toUpperCase(Locale.ENGLISH))) {
                            manEntry = getEntry0(name);
                            break;
                        }
                    }
                }
            }
            this.manEntry = manEntry;
        }
        return manEntry;
    }

   
Returns true iff this JAR file has a manifest with the Class-Path attribute 
/**
    * Returns {@code true} iff this JAR file has a manifest with the
    * Class-Path attribute
    */
    boolean hasClassPathAttribute() throws IOException {
        checkForSpecialAttributes();
        return hasClassPathAttribute;
    }

    
Returns true if the pattern src is found in b. The lastOcc array is the precomputed bad character shifts. Since there are no repeated substring in our search strings, the good suffix shifts can be replaced with a comparison. 
/**
     * Returns true if the pattern {@code src} is found in {@code b}.
     * The {@code lastOcc} array is the precomputed bad character shifts.
     * Since there are no repeated substring in our search strings,
     * the good suffix shifts can be replaced with a comparison.
     */
    private int match(byte[] src, byte[] b, byte[] lastOcc, byte[] optoSft) {
        int len = src.length;
        int last = b.length - len;
        int i = 0;
        next:
        while (i <= last) {
            for (int j = (len - 1); j >= 0; j--) {
                byte c = b[i + j];
                if (c >= ' ' && c <= 'z') {
                    if (c >= 'a') c -= 32; // Canonicalize

                    if (c != src[j]) {
                        // no match
                        int badShift = lastOcc[c - 32];
                        i += Math.max(j + 1 - badShift, optoSft[j]);
                        continue next;
                    }
                } else {
                    // no match, character not valid for name
                    i += len;
                    continue next;
                }
            }
            return i;
        }
        return -1;
    }

    
On first invocation, check if the JAR file has the Class-Path
and the Multi-Release attribute. A no-op on subsequent calls.

/**
     * On first invocation, check if the JAR file has the Class-Path
     * and the Multi-Release attribute. A no-op on subsequent calls.
     */
    private void checkForSpecialAttributes() throws IOException {
        if (hasCheckedSpecialAttributes) {
            return;
        }
        synchronized (this) {
            if (hasCheckedSpecialAttributes) {
                return;
            }
            JarEntry manEntry = getManEntry();
            if (manEntry != null) {
                byte[] b = getBytes(manEntry);
                hasClassPathAttribute = match(CLASSPATH_CHARS, b,
                        CLASSPATH_LASTOCC, CLASSPATH_OPTOSFT) != -1;
                // is this a multi-release jar file
                if (MULTI_RELEASE_ENABLED) {
                    int i = match(MULTIRELEASE_CHARS, b, MULTIRELEASE_LASTOCC,
                            MULTIRELEASE_OPTOSFT);
                    if (i != -1) {
                        // Read the main attributes of the manifest
                        byte[] lbuf = new byte[512];
                        Attributes attr = new Attributes();
                        attr.read(new Manifest.FastInputStream(
                            new ByteArrayInputStream(b)), lbuf);
                        isMultiRelease = Boolean.parseBoolean(
                            attr.getValue(Attributes.Name.MULTI_RELEASE));
                    }
                }
            }
            hasCheckedSpecialAttributes = true;
        }
    }

    synchronized void ensureInitialization() {
        try {
            maybeInstantiateVerifier();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        if (jv != null && !jvInitialized) {
            isInitializing.set(Boolean.TRUE);
            try {
                initializeVerifier();
                jvInitialized = true;
            } finally {
                isInitializing.set(Boolean.FALSE);
            }
        }
    }

    static boolean isInitializing() {
        Boolean value = isInitializing.get();
        return (value == null) ? false : value;
    }

    /*
     * Returns a versioned {@code JarFileEntry} for the given entry,
     * if there is one. Otherwise returns the original entry. This
     * is invoked by the {@code entries2} for verifier.
     */
    JarEntry newEntry(JarEntry je) {
        if (isMultiRelease()) {
            return getVersionedEntry(je.getName(), je);
        }
        return je;
    }

    /*
     * Returns a versioned {@code JarFileEntry} for the given entry
     * name, if there is one. Otherwise returns a {@code JarFileEntry}
     * with the given name. It is invoked from JarVerifier's entries2
     * for {@code singers}.
     */
    JarEntry newEntry(String name) {
        if (isMultiRelease()) {
            JarEntry vje = getVersionedEntry(name, (JarEntry)null);
            if (vje != null) {
                return vje;
            }
        }
        return new JarFileEntry(name);
    }

    Enumeration<String> entryNames(CodeSource[] cs) {
        ensureInitialization();
        if (jv != null) {
            return jv.entryNames(this, cs);
        }

        /*
         * JAR file has no signed content. Is there a non-signing
         * code source?
         */
        boolean includeUnsigned = false;
        for (CodeSource c : cs) {
            if (c.getCodeSigners() == null) {
                includeUnsigned = true;
                break;
            }
        }
        if (includeUnsigned) {
            return unsignedEntryNames();
        } else {
            return Collections.emptyEnumeration();
        }
    }

    
Returns an enumeration of the zip file entries
excluding internal JAR mechanism entries and including
signed entries missing from the ZIP directory.

/**
     * Returns an enumeration of the zip file entries
     * excluding internal JAR mechanism entries and including
     * signed entries missing from the ZIP directory.
     */
    Enumeration<JarEntry> entries2() {
        ensureInitialization();
        if (jv != null) {
            return jv.entries2(this, JUZFA.entries(JarFile.this,
                                                   JarFileEntry::new));
        }

        // screen out entries which are never signed
        final var unfilteredEntries = JUZFA.entries(JarFile.this, JarFileEntry::new);

        return new Enumeration<>() {

            JarEntry entry;

            public boolean hasMoreElements() {
                if (entry != null) {
                    return true;
                }
                while (unfilteredEntries.hasMoreElements()) {
                    JarEntry je = unfilteredEntries.nextElement();
                    if (JarVerifier.isSigningRelated(je.getName())) {
                        continue;
                    }
                    entry = je;
                    return true;
                }
                return false;
            }

            public JarEntry nextElement() {
                if (hasMoreElements()) {
                    JarEntry je = entry;
                    entry = null;
                    return newEntry(je);
                }
                throw new NoSuchElementException();
            }
        };
    }

    CodeSource[] getCodeSources(URL url) {
        ensureInitialization();
        if (jv != null) {
            return jv.getCodeSources(this, url);
        }

        /*
         * JAR file has no signed content. Is there a non-signing
         * code source?
         */
        Enumeration<String> unsigned = unsignedEntryNames();
        if (unsigned.hasMoreElements()) {
            return new CodeSource[]{JarVerifier.getUnsignedCS(url)};
        } else {
            return null;
        }
    }

    private Enumeration<String> unsignedEntryNames() {
        final Enumeration<JarEntry> entries = entries();
        return new Enumeration<>() {

            String name;

            /*
             * Grab entries from ZIP directory but screen out
             * metadata.
             */
            public boolean hasMoreElements() {
                if (name != null) {
                    return true;
                }
                while (entries.hasMoreElements()) {
                    String value;
                    ZipEntry e = entries.nextElement();
                    value = e.getName();
                    if (e.isDirectory() || JarVerifier.isSigningRelated(value)) {
                        continue;
                    }
                    name = value;
                    return true;
                }
                return false;
            }

            public String nextElement() {
                if (hasMoreElements()) {
                    String value = name;
                    name = null;
                    return value;
                }
                throw new NoSuchElementException();
            }
        };
    }

    CodeSource getCodeSource(URL url, String name) {
        ensureInitialization();
        if (jv != null) {
            if (jv.eagerValidation) {
                CodeSource cs = null;
                JarEntry je = getJarEntry(name);
                if (je != null) {
                    cs = jv.getCodeSource(url, this, je);
                } else {
                    cs = jv.getCodeSource(url, name);
                }
                return cs;
            } else {
                return jv.getCodeSource(url, name);
            }
        }

        return JarVerifier.getUnsignedCS(url);
    }

    void setEagerValidation(boolean eager) {
        try {
            maybeInstantiateVerifier();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        if (jv != null) {
            jv.setEagerValidation(eager);
        }
    }

    List<Object> getManifestDigests() {
        ensureInitialization();
        if (jv != null) {
            return jv.getManifestDigests();
        }
        return new ArrayList<>();
    }
}