Java tutorial
/* * Copyright (c) 1997, 2019, 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 * or visit www.oracle.com if you need additional information or have any * questions. */ package java.net; import java.io.IOException; import java.util.jar.JarFile; import java.util.jar.JarEntry; import java.util.jar.Attributes; import java.util.jar.Manifest; import java.security.Permission; import sun.net.www.ParseUtil; /** * A URL Connection to a Java ARchive (JAR) file or an entry in a JAR * file. * * <p>The syntax of a JAR URL is: * * <pre> * jar:<url>!/{entry} * </pre> * * <p>for example: * * <p>{@code jar:http://www.foo.com/bar/baz.jar!/COM/foo/Quux.class} * * <p>Jar URLs should be used to refer to a JAR file or entries in * a JAR file. The example above is a JAR URL which refers to a JAR * entry. If the entry name is omitted, the URL refers to the whole * JAR file: * * {@code jar:http://www.foo.com/bar/baz.jar!/} * * <p>Users should cast the generic URLConnection to a * JarURLConnection when they know that the URL they created is a JAR * URL, and they need JAR-specific functionality. For example: * * <pre> * URL url = new URL("jar:file:/home/duke/duke.jar!/"); * JarURLConnection jarConnection = (JarURLConnection)url.openConnection(); * Manifest manifest = jarConnection.getManifest(); * </pre> * * <p>JarURLConnection instances can only be used to read from JAR files. * It is not possible to get a {@link java.io.OutputStream} to modify or write * to the underlying JAR file using this class. * <p>Examples: * * <dl> * * <dt>A Jar entry * <dd>{@code jar:http://www.foo.com/bar/baz.jar!/COM/foo/Quux.class} * * <dt>A Jar file * <dd>{@code jar:http://www.foo.com/bar/baz.jar!/} * * <dt>A Jar directory * <dd>{@code jar:http://www.foo.com/bar/baz.jar!/COM/foo/} * * </dl> * * <p>{@code !/} is referred to as the <em>separator</em>. * * <p>When constructing a JAR url via {@code new URL(context, spec)}, * the following rules apply: * * <ul> * * <li>if there is no context URL and the specification passed to the * URL constructor doesn't contain a separator, the URL is considered * to refer to a JarFile. * * <li>if there is a context URL, the context URL is assumed to refer * to a JAR file or a Jar directory. * * <li>if the specification begins with a '/', the Jar directory is * ignored, and the spec is considered to be at the root of the Jar * file. * * <p>Examples: * * <dl> * * <dt>context: <b>jar:http://www.foo.com/bar/jar.jar!/</b>, * spec:<b>baz/entry.txt</b> * * <dd>url:<b>jar:http://www.foo.com/bar/jar.jar!/baz/entry.txt</b> * * <dt>context: <b>jar:http://www.foo.com/bar/jar.jar!/baz</b>, * spec:<b>entry.txt</b> * * <dd>url:<b>jar:http://www.foo.com/bar/jar.jar!/baz/entry.txt</b> * * <dt>context: <b>jar:http://www.foo.com/bar/jar.jar!/baz</b>, * spec:<b>/entry.txt</b> * * <dd>url:<b>jar:http://www.foo.com/bar/jar.jar!/entry.txt</b> * * </dl> * * </ul> * * @see java.net.URL * @see java.net.URLConnection * * @see java.util.jar.JarFile * @see java.util.jar.JarInputStream * @see java.util.jar.Manifest * @see java.util.zip.ZipEntry * * @author Benjamin Renaud * @since 1.2 */ public abstract class JarURLConnection extends URLConnection { private URL jarFileURL; private String entryName; /** * The connection to the JAR file URL, if the connection has been * initiated. This should be set by connect. */ protected URLConnection jarFileURLConnection; /** * Creates the new JarURLConnection to the specified URL. * @param url the URL * @throws MalformedURLException if no legal protocol * could be found in a specification string or the * string could not be parsed. */ protected JarURLConnection(URL url) throws MalformedURLException { super(url); parseSpecs(url); } /* get the specs for a given url out of the cache, and compute and * cache them if they're not there. */ private void parseSpecs(URL url) throws MalformedURLException { String spec = url.getFile(); int separator = spec.indexOf("!/"); /* * REMIND: we don't handle nested JAR URLs */ if (separator == -1) { throw new MalformedURLException("no !/ found in url spec:" + spec); } jarFileURL = new URL(spec.substring(0, separator++)); /* * The url argument may have had a runtime fragment appended, so * we need to add a runtime fragment to the jarFileURL to enable * runtime versioning when the underlying jar file is opened. */ if ("runtime".equals(url.getRef())) { jarFileURL = new URL(jarFileURL, "#runtime"); } entryName = null; /* if ! is the last letter of the innerURL, entryName is null */ if (++separator != spec.length()) { entryName = spec.substring(separator, spec.length()); entryName = ParseUtil.decode(entryName); } } /** * Returns the URL for the Jar file for this connection. * * @return the URL for the Jar file for this connection. */ public URL getJarFileURL() { return jarFileURL; } /** * Return the entry name for this connection. This method * returns null if the JAR file URL corresponding to this * connection points to a JAR file and not a JAR file entry. * * @return the entry name for this connection, if any. */ public String getEntryName() { return entryName; } /** * Return the JAR file for this connection. * * @return the JAR file for this connection. If the connection is * a connection to an entry of a JAR file, the JAR file object is * returned * * @exception IOException if an IOException occurs while trying to * connect to the JAR file for this connection. * * @see #connect */ public abstract JarFile getJarFile() throws IOException; /** * Returns the Manifest for this connection, or null if none. * * @return the manifest object corresponding to the JAR file object * for this connection. * * @exception IOException if getting the JAR file for this * connection causes an IOException to be thrown. * * @see #getJarFile */ public Manifest getManifest() throws IOException { return getJarFile().getManifest(); } /** * Return the JAR entry object for this connection, if any. This * method returns null if the JAR file URL corresponding to this * connection points to a JAR file and not a JAR file entry. * * @return the JAR entry object for this connection, or null if * the JAR URL for this connection points to a JAR file. * * @exception IOException if getting the JAR file for this * connection causes an IOException to be thrown. * * @see #getJarFile * @see #getJarEntry */ public JarEntry getJarEntry() throws IOException { return entryName == null ? null : getJarFile().getJarEntry(entryName); } /** * Return the Attributes object for this connection if the URL * for it points to a JAR file entry, null otherwise. * * @return the Attributes object for this connection if the URL * for it points to a JAR file entry, null otherwise. * * @exception IOException if getting the JAR entry causes an * IOException to be thrown. * * @see #getJarEntry */ public Attributes getAttributes() throws IOException { JarEntry e = getJarEntry(); return e != null ? e.getAttributes() : null; } /** * Returns the main Attributes for the JAR file for this * connection. * * @return the main Attributes for the JAR file for this * connection. * * @exception IOException if getting the manifest causes an * IOException to be thrown. * * @see #getJarFile * @see #getManifest */ public Attributes getMainAttributes() throws IOException { Manifest man = getManifest(); return man != null ? man.getMainAttributes() : null; } /** * Returns the Certificate objects for this connection if the URL * for it points to a JAR file entry, null otherwise. This method * can only be called once * the connection has been completely verified by reading * from the input stream until the end of the stream has been * reached. Otherwise, this method will return {@code null} * * @return the Certificate object for this connection if the URL * for it points to a JAR file entry, null otherwise. * * @exception IOException if getting the JAR entry causes an * IOException to be thrown. * * @see #getJarEntry */ public java.security.cert.Certificate[] getCertificates() throws IOException { JarEntry e = getJarEntry(); return e != null ? e.getCertificates() : null; } }