https://tomcat.apache.org/: javax.servlet package 
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package javax.servlet.http;

import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.ServletRequest;


Extends the ServletRequest interface to provide request information for HTTP servlets. 

The servlet container creates an HttpServletRequest object and
passes it as an argument to the servlet's service methods
(doGet, doPost, etc).

/**
 * Extends the {@link javax.servlet.ServletRequest} interface to provide request
 * information for HTTP servlets.
 * <p>
 * The servlet container creates an <code>HttpServletRequest</code> object and
 * passes it as an argument to the servlet's service methods
 * (<code>doGet</code>, <code>doPost</code>, etc).
 */
public interface HttpServletRequest extends ServletRequest {

    
String identifier for Basic authentication. Value "BASIC"

/**
     * String identifier for Basic authentication. Value "BASIC"
     */
    public static final String BASIC_AUTH = "BASIC";
    
String identifier for Form authentication. Value "FORM"

/**
     * String identifier for Form authentication. Value "FORM"
     */
    public static final String FORM_AUTH = "FORM";
    
String identifier for Client Certificate authentication. Value
"CLIENT_CERT"

/**
     * String identifier for Client Certificate authentication. Value
     * "CLIENT_CERT"
     */
    public static final String CLIENT_CERT_AUTH = "CLIENT_CERT";
    
String identifier for Digest authentication. Value "DIGEST"

/**
     * String identifier for Digest authentication. Value "DIGEST"
     */
    public static final String DIGEST_AUTH = "DIGEST";

    
Returns the name of the authentication scheme used to protect the
servlet. All servlet containers support basic, form and client
certificate authentication, and may additionally support digest
authentication. If the servlet is not authenticated null is
returned.


Same as the value of the CGI variable AUTH_TYPE.

Returns:one of the static members BASIC_AUTH, FORM_AUTH, CLIENT_CERT_AUTH,
        DIGEST_AUTH (suitable for == comparison) or the
        container-specific string indicating the authentication scheme,
        or null if the request was not authenticated.
/**
     * Returns the name of the authentication scheme used to protect the
     * servlet. All servlet containers support basic, form and client
     * certificate authentication, and may additionally support digest
     * authentication. If the servlet is not authenticated <code>null</code> is
     * returned.
     * <p>
     * Same as the value of the CGI variable AUTH_TYPE.
     *
     * @return one of the static members BASIC_AUTH, FORM_AUTH, CLIENT_CERT_AUTH,
     *         DIGEST_AUTH (suitable for == comparison) or the
     *         container-specific string indicating the authentication scheme,
     *         or <code>null</code> if the request was not authenticated.
     */
    public String getAuthType();

    
Returns an array containing all of the Cookie objects the
client sent with this request. This method returns null if
no cookies were sent.

Returns:an array of all the Cookies included with this
        request, or null if the request has no cookies
/**
     * Returns an array containing all of the <code>Cookie</code> objects the
     * client sent with this request. This method returns <code>null</code> if
     * no cookies were sent.
     *
     * @return an array of all the <code>Cookies</code> included with this
     *         request, or <code>null</code> if the request has no cookies
     */
    public Cookie[] getCookies();

    
Returns the value of the specified request header as a long
value that represents a Date object. Use this method with
headers that contain dates, such as If-Modified-Since.


The date is returned as the number of milliseconds since January 1, 1970
GMT. The header name is case insensitive.


If the request did not have a header of the specified name, this method
returns -1. If the header can't be converted to a date, the method throws
an IllegalArgumentException.

Params:
  • name – 
           a String specifying the name of the header
Throws:
Returns:a long value representing the date specified in the
        header expressed as the number of milliseconds since January 1,
        1970 GMT, or -1 if the named header was not included with the
        request
/**
     * Returns the value of the specified request header as a <code>long</code>
     * value that represents a <code>Date</code> object. Use this method with
     * headers that contain dates, such as <code>If-Modified-Since</code>.
     * <p>
     * The date is returned as the number of milliseconds since January 1, 1970
     * GMT. The header name is case insensitive.
     * <p>
     * If the request did not have a header of the specified name, this method
     * returns -1. If the header can't be converted to a date, the method throws
     * an <code>IllegalArgumentException</code>.
     *
     * @param name
     *            a <code>String</code> specifying the name of the header
     * @return a <code>long</code> value representing the date specified in the
     *         header expressed as the number of milliseconds since January 1,
     *         1970 GMT, or -1 if the named header was not included with the
     *         request
     * @exception IllegalArgumentException
     *                If the header value can't be converted to a date
     */
    public long getDateHeader(String name);

    
Returns the value of the specified request header as a
String. If the request did not include a header of the
specified name, this method returns null. If there are
multiple headers with the same name, this method returns the first head
in the request. The header name is case insensitive. You can use this
method with any request header.

Params:
  • name – 
           a String specifying the header name
Returns:a String containing the value of the requested
        header, or null if the request does not have a
        header of that name
/**
     * Returns the value of the specified request header as a
     * <code>String</code>. If the request did not include a header of the
     * specified name, this method returns <code>null</code>. If there are
     * multiple headers with the same name, this method returns the first head
     * in the request. The header name is case insensitive. You can use this
     * method with any request header.
     *
     * @param name
     *            a <code>String</code> specifying the header name
     * @return a <code>String</code> containing the value of the requested
     *         header, or <code>null</code> if the request does not have a
     *         header of that name
     */
    public String getHeader(String name);

    
Returns all the values of the specified request header as an
Enumeration of String objects.


Some headers, such as Accept-Language can be sent by clients
as several headers each with a different value rather than sending the
header as a comma separated list.


If the request did not include any headers of the specified name, this
method returns an empty Enumeration. The header name is case
insensitive. You can use this method with any request header.

Params:
  • name – 
           a String specifying the header name
Returns:an Enumeration containing the values of the requested
        header. If the request does not have any headers of that name
        return an empty enumeration. If the container does not allow
        access to header information, return null
/**
     * Returns all the values of the specified request header as an
     * <code>Enumeration</code> of <code>String</code> objects.
     * <p>
     * Some headers, such as <code>Accept-Language</code> can be sent by clients
     * as several headers each with a different value rather than sending the
     * header as a comma separated list.
     * <p>
     * If the request did not include any headers of the specified name, this
     * method returns an empty <code>Enumeration</code>. The header name is case
     * insensitive. You can use this method with any request header.
     *
     * @param name
     *            a <code>String</code> specifying the header name
     * @return an <code>Enumeration</code> containing the values of the requested
     *         header. If the request does not have any headers of that name
     *         return an empty enumeration. If the container does not allow
     *         access to header information, return null
     */
    public Enumeration<String> getHeaders(String name);

    
Returns an enumeration of all the header names this request contains. If
the request has no headers, this method returns an empty enumeration.


Some servlet containers do not allow servlets to access headers using
this method, in which case this method returns null

Returns:an enumeration of all the header names sent with this request; if
        the request has no headers, an empty enumeration; if the servlet
        container does not allow servlets to use this method,
        null
/**
     * Returns an enumeration of all the header names this request contains. If
     * the request has no headers, this method returns an empty enumeration.
     * <p>
     * Some servlet containers do not allow servlets to access headers using
     * this method, in which case this method returns <code>null</code>
     *
     * @return an enumeration of all the header names sent with this request; if
     *         the request has no headers, an empty enumeration; if the servlet
     *         container does not allow servlets to use this method,
     *         <code>null</code>
     */
    public Enumeration<String> getHeaderNames();

    
Returns the value of the specified request header as an int.
If the request does not have a header of the specified name, this method
returns -1. If the header cannot be converted to an integer, this method
throws a NumberFormatException.


The header name is case insensitive.

Params:
  • name – 
           a String specifying the name of a request header
Throws:
Returns:an integer expressing the value of the request header or -1 if the
        request doesn't have a header of this name
/**
     * Returns the value of the specified request header as an <code>int</code>.
     * If the request does not have a header of the specified name, this method
     * returns -1. If the header cannot be converted to an integer, this method
     * throws a <code>NumberFormatException</code>.
     * <p>
     * The header name is case insensitive.
     *
     * @param name
     *            a <code>String</code> specifying the name of a request header
     * @return an integer expressing the value of the request header or -1 if the
     *         request doesn't have a header of this name
     * @exception NumberFormatException
     *                If the header value can't be converted to an
     *                <code>int</code>
     */
    public int getIntHeader(String name);

    public default HttpServletMapping getHttpServletMapping() {
        return new HttpServletMapping() {

            @Override
            public String getMatchValue() {
                return "";
            }

            @Override
            public String getPattern() {
                return "";
            }

            @Override
            public String getServletName() {
                return "";
            }

            @Override
            public MappingMatch getMappingMatch() {
                return null;
            }
        };
    }

    
Returns the name of the HTTP method with which this request was made, for
example, GET, POST, or PUT. Same as the value of the CGI variable
REQUEST_METHOD.

Returns:a String specifying the name of the method with
        which this request was made
/**
     * Returns the name of the HTTP method with which this request was made, for
     * example, GET, POST, or PUT. Same as the value of the CGI variable
     * REQUEST_METHOD.
     *
     * @return a <code>String</code> specifying the name of the method with
     *         which this request was made
     */
    public String getMethod();

    
Returns any extra path information associated with the URL the client
sent when it made this request. The extra path information follows the
servlet path but precedes the query string and will start with a "/"
character.


This method returns null if there was no extra path
information.


Same as the value of the CGI variable PATH_INFO.

Returns:a String, decoded by the web container, specifying
        extra path information that comes after the servlet path but
        before the query string in the request URL; or null
        if the URL does not have any extra path information
/**
     * Returns any extra path information associated with the URL the client
     * sent when it made this request. The extra path information follows the
     * servlet path but precedes the query string and will start with a "/"
     * character.
     * <p>
     * This method returns <code>null</code> if there was no extra path
     * information.
     * <p>
     * Same as the value of the CGI variable PATH_INFO.
     *
     * @return a <code>String</code>, decoded by the web container, specifying
     *         extra path information that comes after the servlet path but
     *         before the query string in the request URL; or <code>null</code>
     *         if the URL does not have any extra path information
     */
    public String getPathInfo();

    
Returns any extra path information after the servlet name but before the
query string, and translates it to a real path. Same as the value of the
CGI variable PATH_TRANSLATED.


If the URL does not have any extra path information, this method returns
null or the servlet container cannot translate the virtual
path to a real path for any reason (such as when the web application is
executed from an archive). The web container does not decode this string.

Returns:a String specifying the real path, or
        null if the URL does not have any extra path
        information
/**
     * Returns any extra path information after the servlet name but before the
     * query string, and translates it to a real path. Same as the value of the
     * CGI variable PATH_TRANSLATED.
     * <p>
     * If the URL does not have any extra path information, this method returns
     * <code>null</code> or the servlet container cannot translate the virtual
     * path to a real path for any reason (such as when the web application is
     * executed from an archive). The web container does not decode this string.
     *
     * @return a <code>String</code> specifying the real path, or
     *         <code>null</code> if the URL does not have any extra path
     *         information
     */
    public String getPathTranslated();

    
Obtain a builder for generating push requests. PushBuilder documents how this request will be used as the basis for a push request. Each call to this method will return a new instance, independent of any previous instance obtained. 
Returns:A builder that can be used to generate push requests based on this request or null if push is not supported. Note that even if a PushBuilder instance is returned, by the time that PushBuilder.push() is called, it may no longer be valid to push a request and the push request will be ignored.
Since:Servlet 4.0
/**
     * Obtain a builder for generating push requests. {@link PushBuilder}
     * documents how this request will be used as the basis for a push request.
     * Each call to this method will return a new instance, independent of any
     * previous instance obtained.
     *
     * @return A builder that can be used to generate push requests based on
     *         this request or {@code null} if push is not supported. Note that
     *         even if a PushBuilder instance is returned, by the time that
     *         {@link PushBuilder#push()} is called, it may no longer be valid
     *         to push a request and the push request will be ignored.
     *
     * @since Servlet 4.0
     */
    public default PushBuilder newPushBuilder() {
        return null;
    }

    
Returns the portion of the request URI that indicates the context of the
request. The context path always comes first in a request URI. The path
starts with a "/" character but does not end with a "/" character. For
servlets in the default (root) context, this method returns "". The
container does not decode this string.

Returns:a String specifying the portion of the request URI
        that indicates the context of the request
/**
     * Returns the portion of the request URI that indicates the context of the
     * request. The context path always comes first in a request URI. The path
     * starts with a "/" character but does not end with a "/" character. For
     * servlets in the default (root) context, this method returns "". The
     * container does not decode this string.
     *
     * @return a <code>String</code> specifying the portion of the request URI
     *         that indicates the context of the request
     */
    public String getContextPath();

    
Returns the query string that is contained in the request URL after the
path. This method returns null if the URL does not have a
query string. Same as the value of the CGI variable QUERY_STRING.

Returns:a String containing the query string or
        null if the URL contains no query string. The value
        is not decoded by the container.
/**
     * Returns the query string that is contained in the request URL after the
     * path. This method returns <code>null</code> if the URL does not have a
     * query string. Same as the value of the CGI variable QUERY_STRING.
     *
     * @return a <code>String</code> containing the query string or
     *         <code>null</code> if the URL contains no query string. The value
     *         is not decoded by the container.
     */
    public String getQueryString();

    
Returns the login of the user making this request, if the user has been
authenticated, or null if the user has not been
authenticated. Whether the user name is sent with each subsequent request
depends on the browser and type of authentication. Same as the value of
the CGI variable REMOTE_USER.

Returns:a String specifying the login of the user making
        this request, or null if the user login is not known
/**
     * Returns the login of the user making this request, if the user has been
     * authenticated, or <code>null</code> if the user has not been
     * authenticated. Whether the user name is sent with each subsequent request
     * depends on the browser and type of authentication. Same as the value of
     * the CGI variable REMOTE_USER.
     *
     * @return a <code>String</code> specifying the login of the user making
     *         this request, or <code>null</code> if the user login is not known
     */
    public String getRemoteUser();

    
Returns a boolean indicating whether the authenticated user is included
in the specified logical "role". Roles and role membership can be defined
using deployment descriptors. If the user has not been authenticated, the
method returns false.

Params:
  • role – 
           a String specifying the name of the role
Returns:a boolean indicating whether the user making this
        request belongs to a given role; false if the user
        has not been authenticated
/**
     * Returns a boolean indicating whether the authenticated user is included
     * in the specified logical "role". Roles and role membership can be defined
     * using deployment descriptors. If the user has not been authenticated, the
     * method returns <code>false</code>.
     *
     * @param role
     *            a <code>String</code> specifying the name of the role
     * @return a <code>boolean</code> indicating whether the user making this
     *         request belongs to a given role; <code>false</code> if the user
     *         has not been authenticated
     */
    public boolean isUserInRole(String role);

    
Returns a java.security.Principal object containing the name
of the current authenticated user. If the user has not been
authenticated, the method returns null.

Returns:a java.security.Principal containing the name of the
        user making this request; null if the user has not
        been authenticated
/**
     * Returns a <code>java.security.Principal</code> object containing the name
     * of the current authenticated user. If the user has not been
     * authenticated, the method returns <code>null</code>.
     *
     * @return a <code>java.security.Principal</code> containing the name of the
     *         user making this request; <code>null</code> if the user has not
     *         been authenticated
     */
    public java.security.Principal getUserPrincipal();

    
Returns the session ID specified by the client. This may not be the same
as the ID of the current valid session for this request. If the client
did not specify a session ID, this method returns null.

See Also:
Returns:a String specifying the session ID, or
        null if the request did not specify a session ID
/**
     * Returns the session ID specified by the client. This may not be the same
     * as the ID of the current valid session for this request. If the client
     * did not specify a session ID, this method returns <code>null</code>.
     *
     * @return a <code>String</code> specifying the session ID, or
     *         <code>null</code> if the request did not specify a session ID
     * @see #isRequestedSessionIdValid
     */
    public String getRequestedSessionId();

    
Returns the part of this request's URL from the protocol name up to the
query string in the first line of the HTTP request. The web container
does not decode this String. For example:


Examples of Returned Values


First line of HTTP request
Returned Value


POST /some/path.html HTTP/1.1

/some/path.html


GET http://foo.bar/a.html HTTP/1.0

/a.html


HEAD /xyz?a=b HTTP/1.1

/xyz



 To reconstruct a URL with a scheme and host, use getRequestURL. 
See Also:
Returns:a String containing the part of the URL from the
        protocol name up to the query string
/**
     * Returns the part of this request's URL from the protocol name up to the
     * query string in the first line of the HTTP request. The web container
     * does not decode this String. For example:
     * <table>
     * <caption>Examples of Returned Values</caption>
     * <tr>
     * <th>First line of HTTP request</th>
     * <th>Returned Value</th>
     * <tr>
     * <td>POST /some/path.html HTTP/1.1
     * <td>
     * <td>/some/path.html
     * <tr>
     * <td>GET http://foo.bar/a.html HTTP/1.0
     * <td>
     * <td>/a.html
     * <tr>
     * <td>HEAD /xyz?a=b HTTP/1.1
     * <td>
     * <td>/xyz
     * </table>
     * <p>
     * To reconstruct a URL with a scheme and host, use
     * {@link #getRequestURL}.
     *
     * @return a <code>String</code> containing the part of the URL from the
     *         protocol name up to the query string
     * @see #getRequestURL
     */
    public String getRequestURI();

    
Reconstructs the URL the client used to make the request. The returned
URL contains a protocol, server name, port number, and server path, but
it does not include query string parameters.


Because this method returns a StringBuffer, not a string,
you can modify the URL easily, for example, to append query parameters.


This method is useful for creating redirect messages and for reporting
errors.

Returns:a StringBuffer object containing the reconstructed
        URL
/**
     * Reconstructs the URL the client used to make the request. The returned
     * URL contains a protocol, server name, port number, and server path, but
     * it does not include query string parameters.
     * <p>
     * Because this method returns a <code>StringBuffer</code>, not a string,
     * you can modify the URL easily, for example, to append query parameters.
     * <p>
     * This method is useful for creating redirect messages and for reporting
     * errors.
     *
     * @return a <code>StringBuffer</code> object containing the reconstructed
     *         URL
     */
    public StringBuffer getRequestURL();

    
Returns the part of this request's URL that calls the servlet. This path
starts with a "/" character and includes either the servlet name or a
path to the servlet, but does not include any extra path information or a
query string. Same as the value of the CGI variable SCRIPT_NAME.


This method will return an empty string ("") if the servlet used to
process this request was matched using the "/*" pattern.

Returns:a String containing the name or path of the servlet
        being called, as specified in the request URL, decoded, or an
        empty string if the servlet used to process the request is
        matched using the "/*" pattern.
/**
     * Returns the part of this request's URL that calls the servlet. This path
     * starts with a "/" character and includes either the servlet name or a
     * path to the servlet, but does not include any extra path information or a
     * query string. Same as the value of the CGI variable SCRIPT_NAME.
     * <p>
     * This method will return an empty string ("") if the servlet used to
     * process this request was matched using the "/*" pattern.
     *
     * @return a <code>String</code> containing the name or path of the servlet
     *         being called, as specified in the request URL, decoded, or an
     *         empty string if the servlet used to process the request is
     *         matched using the "/*" pattern.
     */
    public String getServletPath();

    
Returns the current HttpSession associated with this request
or, if there is no current session and create is true,
returns a new session.


If create is false and the request has no valid
HttpSession, this method returns null.


To make sure the session is properly maintained, you must call this
method before the response is committed. If the container is using
cookies to maintain session integrity and is asked to create a new
session when the response is committed, an IllegalStateException is
thrown.

Params:
  • create – 
           true to create a new session for this request if
           necessary; false to return null if
           there's no current session
See Also:
Returns:the HttpSession associated with this request or
        null if create is false
        and the request has no valid session
/**
     * Returns the current <code>HttpSession</code> associated with this request
     * or, if there is no current session and <code>create</code> is true,
     * returns a new session.
     * <p>
     * If <code>create</code> is <code>false</code> and the request has no valid
     * <code>HttpSession</code>, this method returns <code>null</code>.
     * <p>
     * To make sure the session is properly maintained, you must call this
     * method before the response is committed. If the container is using
     * cookies to maintain session integrity and is asked to create a new
     * session when the response is committed, an IllegalStateException is
     * thrown.
     *
     * @param create
     *            <code>true</code> to create a new session for this request if
     *            necessary; <code>false</code> to return <code>null</code> if
     *            there's no current session
     * @return the <code>HttpSession</code> associated with this request or
     *         <code>null</code> if <code>create</code> is <code>false</code>
     *         and the request has no valid session
     * @see #getSession()
     */
    public HttpSession getSession(boolean create);

    
Returns the current session associated with this request, or if the
request does not have a session, creates one.

See Also:
Returns:the HttpSession associated with this request
/**
     * Returns the current session associated with this request, or if the
     * request does not have a session, creates one.
     *
     * @return the <code>HttpSession</code> associated with this request
     * @see #getSession(boolean)
     */
    public HttpSession getSession();

    
Changes the session ID of the session associated with this request. This
method does not create a new session object it only changes the ID of the
current session.

See Also:
Returns:the new session ID allocated to the session
Since:Servlet 3.1
/**
     * Changes the session ID of the session associated with this request. This
     * method does not create a new session object it only changes the ID of the
     * current session.
     *
     * @return the new session ID allocated to the session
     * @see HttpSessionIdListener
     * @since Servlet 3.1
     */
    public String changeSessionId();

    
Checks whether the requested session ID is still valid.

See Also:
Returns:true if this request has an id for a valid session
        in the current session context; false otherwise
/**
     * Checks whether the requested session ID is still valid.
     *
     * @return <code>true</code> if this request has an id for a valid session
     *         in the current session context; <code>false</code> otherwise
     * @see #getRequestedSessionId
     * @see #getSession
     */
    public boolean isRequestedSessionIdValid();

    
Checks whether the requested session ID came in as a cookie.

See Also:
Returns:true if the session ID came in as a cookie;
        otherwise, false
/**
     * Checks whether the requested session ID came in as a cookie.
     *
     * @return <code>true</code> if the session ID came in as a cookie;
     *         otherwise, <code>false</code>
     * @see #getSession
     */
    public boolean isRequestedSessionIdFromCookie();

    
Checks whether the requested session ID came in as part of the request
URL.

See Also:
Returns:true if the session ID came in as part of a URL;
        otherwise, false
/**
     * Checks whether the requested session ID came in as part of the request
     * URL.
     *
     * @return <code>true</code> if the session ID came in as part of a URL;
     *         otherwise, <code>false</code>
     * @see #getSession
     */
    public boolean isRequestedSessionIdFromURL();

    
Returns:isRequestedSessionIdFromURL()
Deprecated:As of Version 2.1 of the Java Servlet API, use isRequestedSessionIdFromURL instead.
/**
     * @return {@link #isRequestedSessionIdFromURL()}
     * @deprecated As of Version 2.1 of the Java Servlet API, use
     *             {@link #isRequestedSessionIdFromURL} instead.
     */
    @Deprecated
    public boolean isRequestedSessionIdFromUrl();

    
Triggers the same authentication process as would be triggered if the
request is for a resource that is protected by a security constraint.

Params:
  • response –  The response to use to return any authentication
                 challenge
Throws:
  • IOException – if the authentication process attempted to read from
        the request or write to the response and an I/O error occurred
  • IllegalStateException – if the authentication process attempted to
        write to the response after it had been committed
  • ServletException – if the authentication failed and the caller is
        expected to handle the failure
Returns:true if the user is successfully authenticated and
        false if not
Since:Servlet 3.0
/**
     * Triggers the same authentication process as would be triggered if the
     * request is for a resource that is protected by a security constraint.
     *
     * @param response  The response to use to return any authentication
     *                  challenge
     * @return <code>true</code> if the user is successfully authenticated and
     *         <code>false</code> if not
     *
     * @throws IOException if the authentication process attempted to read from
     *         the request or write to the response and an I/O error occurred
     * @throws IllegalStateException if the authentication process attempted to
     *         write to the response after it had been committed
     * @throws ServletException if the authentication failed and the caller is
     *         expected to handle the failure
     * @since Servlet 3.0
     */
    public boolean authenticate(HttpServletResponse response)
            throws IOException, ServletException;

    
Authenticate the provided user name and password and then associated the
authenticated user with the request.

Params:
  • username –  The user name to authenticate
  • password –  The password to use to authenticate the user
Throws:
Since:Servlet 3.0
/**
     * Authenticate the provided user name and password and then associated the
     * authenticated user with the request.
     *
     * @param username  The user name to authenticate
     * @param password  The password to use to authenticate the user
     *
     * @throws ServletException
     *             If any of {@link #getRemoteUser()},
     *             {@link #getUserPrincipal()} or {@link #getAuthType()} are
     *             non-null, if the configured authenticator does not support
     *             user name and password authentication or if the
     *             authentication fails
     * @since Servlet 3.0
     */
    public void login(String username, String password) throws ServletException;

    
Removes any authenticated user from the request.

Throws:
  • ServletException – 
            If the logout fails
Since:Servlet 3.0
/**
     * Removes any authenticated user from the request.
     *
     * @throws ServletException
     *             If the logout fails
     * @since Servlet 3.0
     */
    public void logout() throws ServletException;

    
Return a collection of all uploaded Parts.

Throws:
Returns:A collection of all uploaded Parts.
Since:Servlet 3.0
/**
     * Return a collection of all uploaded Parts.
     *
     * @return A collection of all uploaded Parts.
     * @throws IOException
     *             if an I/O error occurs
     * @throws IllegalStateException
     *             if size limits are exceeded or no multipart configuration is
     *             provided
     * @throws ServletException
     *             if the request is not multipart/form-data
     * @since Servlet 3.0
     */
    public Collection<Part> getParts() throws IOException,
            ServletException;

    
Gets the named Part or null if the Part does not exist. Triggers upload
of all Parts.

Params:
  • name – The name of the Part to obtain
Throws:
Returns:The named Part or null if the Part does not exist
Since:Servlet 3.0
/**
     * Gets the named Part or null if the Part does not exist. Triggers upload
     * of all Parts.
     *
     * @param name The name of the Part to obtain
     *
     * @return The named Part or null if the Part does not exist
     * @throws IOException
     *             if an I/O error occurs
     * @throws IllegalStateException
     *             if size limits are exceeded
     * @throws ServletException
     *             if the request is not multipart/form-data
     * @since Servlet 3.0
     */
    public Part getPart(String name) throws IOException,
            ServletException;

    
Start the HTTP upgrade process and pass the connection to the provided protocol handler once the current request/response pair has completed processing. Calling this method sets the response status to HttpServletResponse.SC_SWITCHING_PROTOCOLS and flushes the response. Protocol specific headers must have already been set before this method is called. 
Params:
  • httpUpgradeHandlerClass – The class that implements the upgrade
                               handler
Type parameters:
  • <T> –                     The type of the upgrade handler
Throws:
  • IOException – 
            if an I/O error occurred during the upgrade
  • ServletException – 
            if the given httpUpgradeHandlerClass fails to be instantiated
Returns:A newly created instance of the specified upgrade handler type
Since:Servlet 3.1
/**
     * Start the HTTP upgrade process and pass the connection to the provided
     * protocol handler once the current request/response pair has completed
     * processing. Calling this method sets the response status to {@link
     * HttpServletResponse#SC_SWITCHING_PROTOCOLS} and flushes the response.
     * Protocol specific headers must have already been set before this method
     * is called.
     *
     * @param <T>                     The type of the upgrade handler
     * @param httpUpgradeHandlerClass The class that implements the upgrade
     *                                handler
     *
     * @return A newly created instance of the specified upgrade handler type
     *
     * @throws IOException
     *             if an I/O error occurred during the upgrade
     * @throws ServletException
     *             if the given httpUpgradeHandlerClass fails to be instantiated
     * @since Servlet 3.1
     */
    public <T extends HttpUpgradeHandler> T upgrade(
            Class<T> httpUpgradeHandlerClass) throws java.io.IOException, ServletException;

    
Obtain a Map of the trailer fields that is not backed by the request
object.

Returns:A Map of the received trailer fields with all keys lower case
        or an empty Map if no trailers are present
Since:Servlet 4.0
/**
     * Obtain a Map of the trailer fields that is not backed by the request
     * object.
     *
     * @return A Map of the received trailer fields with all keys lower case
     *         or an empty Map if no trailers are present
     *
     * @since Servlet 4.0
     */
    public default Map<String,String> getTrailerFields() {
        return Collections.emptyMap();
    }

    
Are trailer fields ready to be read (there may still be no trailers to read). This method always returns true if the underlying protocol does not support trailer fields. Otherwise, true is returned once all of the following are true: 
    

  • The application has ready all the request data and an EOF has been
    received or the content-length is zero
    • 

  • All trailer fields, if any, have been received
    • 



Returns:true if trailers are ready to be read
Since:Servlet 4.0
/**
     * Are trailer fields ready to be read (there may still be no trailers to
     * read). This method always returns {@code true} if the underlying protocol
     * does not support trailer fields. Otherwise, {@code true} is returned once
     * all of the following are true:
     * <ul>
     * <li>The application has ready all the request data and an EOF has been
     *     received or the content-length is zero</li>
     * <li>All trailer fields, if any, have been received</li>
     * </ul>
     *
     * @return {@code true} if trailers are ready to be read
     *
     * @since Servlet 4.0
     */
    public default boolean isTrailerFieldsReady() {
        return false;
    }
}