package io.dropwizard.servlets.assets;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.JarURLConnection;
import java.net.MalformedURLException;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLConnection;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.zip.ZipEntry;

Helper methods for dealing with URL objects for local resources.
/** * Helper methods for dealing with {@link URL} objects for local resources. */
public class ResourceURL { private ResourceURL() { /* singleton */ }
Returns true if the URL passed to it corresponds to a directory. This is slightly tricky due to some quirks of the JarFile API. Only jar:// and file:// URLs are supported.
Params:
  • resourceURL – the URL to check
Returns:true if resource is a directory
/** * Returns true if the URL passed to it corresponds to a directory. This is slightly tricky due to some quirks * of the {@link JarFile} API. Only jar:// and file:// URLs are supported. * * @param resourceURL the URL to check * @return true if resource is a directory */
public static boolean isDirectory(URL resourceURL) throws URISyntaxException { final String protocol = resourceURL.getProtocol(); switch (protocol) { case "jar": try { final JarURLConnection jarConnection = (JarURLConnection) resourceURL.openConnection(); final JarEntry entry = jarConnection.getJarEntry(); if (entry.isDirectory()) { return true; } // WARNING! Heuristics ahead. // It turns out that JarEntry#isDirectory() really just tests whether the filename ends in a '/'. // If you try to open the same URL without a trailing '/', it'll succeed — but the result won't be // what you want. We try to get around this by calling getInputStream() on the file inside the jar. // This seems to return null for directories (though that behavior is undocumented as far as I // can tell). If you have a better idea, please improve this. final String relativeFilePath = entry.getName(); final JarFile jarFile = jarConnection.getJarFile(); final ZipEntry zipEntry = jarFile.getEntry(relativeFilePath); final InputStream inputStream = jarFile.getInputStream(zipEntry); return inputStream == null; } catch (IOException e) { throw new ResourceNotFoundException(e); } case "file": return new File(resourceURL.toURI()).isDirectory(); default: throw new IllegalArgumentException("Unsupported protocol " + resourceURL.getProtocol() + " for resource " + resourceURL); } }
Appends a trailing '/' to a URL object. Does not append a slash if one is already present.
Params:
  • originalURL – The URL to append a slash to
Returns:a new URL object that ends in a slash
/** * Appends a trailing '/' to a {@link URL} object. Does not append a slash if one is already present. * * @param originalURL The URL to append a slash to * @return a new URL object that ends in a slash */
public static URL appendTrailingSlash(URL originalURL) { try { return originalURL.getPath().endsWith("/") ? originalURL : new URL(originalURL.getProtocol(), originalURL.getHost(), originalURL.getPort(), originalURL.getFile() + '/'); } catch (MalformedURLException ignored) { // shouldn't happen throw new IllegalArgumentException("Invalid resource URL: " + originalURL); } }
Returns the last modified time for file:// and jar:// URLs. This is slightly tricky for a couple of reasons: 1) calling getConnection on a URLConnection to a file opens an InputStream to that file that must then be closed — though this is not true for URLConnections to jar resources 2) calling getLastModified on JarURLConnections returns the last modified time of the jar file, rather than the file within
Params:
  • resourceURL – the URL to return the last modified time for
Returns:the last modified time of the resource, expressed as the number of milliseconds since the epoch, or 0 if there was a problem
/** * Returns the last modified time for file:// and jar:// URLs. This is slightly tricky for a couple of reasons: * 1) calling getConnection on a {@link URLConnection} to a file opens an {@link InputStream} to that file that * must then be closed — though this is not true for {@code URLConnection}s to jar resources * 2) calling getLastModified on {@link JarURLConnection}s returns the last modified time of the jar file, rather * than the file within * * @param resourceURL the URL to return the last modified time for * @return the last modified time of the resource, expressed as the number of milliseconds since the epoch, or 0 * if there was a problem */
public static long getLastModified(URL resourceURL) { final String protocol = resourceURL.getProtocol(); switch (protocol) { case "jar": try { final JarURLConnection jarConnection = (JarURLConnection) resourceURL.openConnection(); final JarEntry entry = jarConnection.getJarEntry(); return entry.getTime(); } catch (IOException ignored) { return 0; } case "file": URLConnection connection = null; try { connection = resourceURL.openConnection(); return connection.getLastModified(); } catch (IOException ignored) { return 0; } finally { if (connection != null) { try { connection.getInputStream().close(); } catch (IOException ignored) { // do nothing. } } } default: throw new IllegalArgumentException("Unsupported protocol " + resourceURL.getProtocol() + " for resource " + resourceURL); } } }