374 lines
11 KiB
Java
374 lines
11 KiB
Java
// URL.java - A Uniform Resource Locator.
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/* Copyright (C) 1999 Red Hat, Inc.
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This file is part of libgcj.
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This software is copyrighted work licensed under the terms of the
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Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
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details. */
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package java.net;
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import java.io.*;
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import java.util.Hashtable;
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import java.util.StringTokenizer;
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/**
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* @author Warren Levy <warrenl@cygnus.com>
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* @date March 4, 1999.
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*/
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/**
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* Written using on-line Java Platform 1.2 API Specification, as well
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* as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
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* Status: Believed complete and correct.
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*/
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public final class URL implements Serializable
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{
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private String protocol;
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private String host;
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private int port = -1; // Initialize for constructor using context.
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private String file;
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private String ref;
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private URLStreamHandler handler;
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private static Hashtable handlers = new Hashtable();
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private static URLStreamHandlerFactory factory;
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public URL(String protocol, String host, int port, String file)
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throws MalformedURLException
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{
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this(protocol, host, port, file, null);
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}
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public URL(String protocol, String host, String file)
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throws MalformedURLException
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{
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this(protocol, host, -1, file, null);
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}
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// JDK1.2
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public URL(String protocol, String host, int port, String file,
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URLStreamHandler handler) throws MalformedURLException
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{
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if (protocol == null)
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throw new MalformedURLException("null protocol");
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this.protocol = protocol;
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if (handler != null)
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{
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// TODO12: Need SecurityManager.checkPermission and
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// TODO12: java.net.NetPermission from JDK 1.2 to be implemented.
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// Throw an exception if an extant security mgr precludes
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// specifying a StreamHandler.
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//
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// SecurityManager s = System.getSecurityManager();
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// if (s != null)
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// s.checkPermission(NetPermission("specifyStreamHandler"));
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this.handler = handler;
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}
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else
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this.handler = setURLStreamHandler(protocol);
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if (this.handler == null)
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throw new MalformedURLException("Handler for protocol not found");
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this.host = host;
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this.port = port;
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int hashAt = file.indexOf('#');
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if (hashAt < 0)
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{
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this.file = file;
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this.ref = null;
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}
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else
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{
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this.file = file.substring(0, hashAt);
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this.ref = file.substring(hashAt + 1);
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}
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}
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public URL(String spec) throws MalformedURLException
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{
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this((URL) null, spec, (URLStreamHandler) null);
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}
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public URL(URL context, String spec) throws MalformedURLException
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{
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this(context, spec, (URLStreamHandler) null);
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}
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// JDK1.2
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public URL(URL context, String spec, URLStreamHandler handler)
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throws MalformedURLException
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{
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/* A protocol is defined by the doc as the substring before a ':'
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* as long as the ':' occurs before any '/'.
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*
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* If context is null, then spec must be an absolute URL.
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*
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* The relative URL need not specify all the components of a URL.
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* If the protocol, host name, or port number is missing, the value
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* is inherited from the context. A bare file component is appended
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* to the context's file. The optional anchor is not inherited.
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*/
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// If this is an absolute URL, then ignore context completely.
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// An absolute URL must have chars prior to "://" but cannot have a colon
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// right after the "://". The second colon is for an optional port value
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// and implies that the host from the context is used if available.
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int colon;
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if ((colon = spec.indexOf("://", 1)) > 0 &&
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! spec.regionMatches(colon, "://:", 0, 4))
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context = null;
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int slash;
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if ((colon = spec.indexOf(':')) > 0 &&
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(colon < (slash = spec.indexOf('/')) || slash < 0))
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{
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// Protocol specified in spec string.
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protocol = spec.substring(0, colon);
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if (context != null && context.protocol.equals(protocol))
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{
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// The 1.2 doc specifically says these are copied to the new URL.
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host = context.host;
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port = context.port;
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file = context.file;
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}
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}
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else if (context != null)
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{
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// Protocol NOT specified in spec string.
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// Use context fields (except ref) as a foundation for relative URLs.
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colon = -1;
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protocol = context.protocol;
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host = context.host;
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port = context.port;
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file = context.file;
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}
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else // Protocol NOT specified in spec. and no context available.
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throw new
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MalformedURLException("Absolute URL required with null context");
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if (handler != null)
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{
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// TODO12: Need SecurityManager.checkPermission and
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// TODO12: java.net.NetPermission from JDK 1.2 to be implemented.
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// Throw an exception if an extant security mgr precludes
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// specifying a StreamHandler.
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//
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// SecurityManager s = System.getSecurityManager();
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// if (s != null)
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// s.checkPermission(NetPermission("specifyStreamHandler"));
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this.handler = handler;
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}
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else
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this.handler = setURLStreamHandler(protocol);
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if (this.handler == null)
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throw new MalformedURLException("Handler for protocol not found");
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// JDK 1.2 doc for parseURL specifically states that any '#' ref
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// is to be excluded by passing the 'limit' as the indexOf the '#'
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// if one exists, otherwise pass the end of the string.
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int hashAt = spec.indexOf('#', colon + 1);
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this.handler.parseURL(this, spec, colon + 1,
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hashAt < 0 ? spec.length() : hashAt);
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if (hashAt >= 0)
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ref = spec.substring(hashAt + 1);
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}
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public boolean equals(Object obj)
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{
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if (obj == null || ! (obj instanceof URL))
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return false;
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URL uObj = (URL) obj;
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// This comparison is very conservative. It assumes that any
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// field can be null.
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return (port == uObj.port
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&& ((protocol == null && uObj.protocol == null)
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|| (protocol != null && protocol.equals(uObj.protocol)))
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&& ((host == null && uObj.host == null)
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|| (host != null && host.equals(uObj.host)))
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&& ((file == null && uObj.file == null)
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|| (file != null && file.equals(uObj.file)))
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&& ((ref == null && uObj.ref == null)
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|| (ref != null && ref.equals(uObj.ref))));
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}
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public final Object getContent() throws IOException
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{
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return openConnection().getContent();
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}
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public String getFile()
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{
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return file;
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}
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public String getHost()
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{
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return host;
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}
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public int getPort()
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{
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return port;
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}
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public String getProtocol()
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{
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return protocol;
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}
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public String getRef()
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{
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return ref;
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}
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public int hashCode()
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{
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// JCL book says this is computed using (only) the hashcodes of the
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// protocol, host and file fields. Empirical evidence indicates this
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// is probably XOR in JDK 1.1. In JDK 1.2 it seems to be a sum including
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// the port.
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//
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// JDK 1.2 online doc infers that host could be null because it
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// explicitly states that file cannot be null but is silent on host.
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// A simple example with protocol "http" (hashcode 3213448), host null,
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// file "/" (hashcode 47) produced a hashcode (3213494) which appeared
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// to be the sum of the two hashcodes plus the port. Another example
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// using "/index.html" for file bore this out; as well as "#" for file
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// (which was reduced to "" with a hashcode of zero). A "" host also
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// causes the port number and the two hashcodes to be summed.
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return (protocol.hashCode() + ((host == null) ? 0 : host.hashCode()) +
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port + file.hashCode());
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}
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public URLConnection openConnection() throws IOException
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{
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return handler.openConnection(this);
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}
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public final InputStream openStream() throws IOException
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{
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return openConnection().getInputStream();
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}
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public boolean sameFile(URL other)
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{
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// This comparison is very conservative. It assumes that any
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// field can be null.
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return (other != null
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&& port == other.port
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&& ((protocol == null && other.protocol == null)
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|| (protocol != null && protocol.equals(other.protocol)))
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&& ((host == null && other.host == null)
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|| (host != null && host.equals(other.host)))
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&& ((file == null && other.file == null)
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|| (file != null && file.equals(other.file))));
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}
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protected void set(String protocol, String host, int port, String file,
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String ref)
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{
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// TBD: Theoretically, a poorly written StreamHandler could pass an
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// invalid protocol. It will cause the handler to be set to null
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// thus overriding a valid handler. Callers of this method should
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// be aware of this.
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this.handler = setURLStreamHandler(protocol);
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this.protocol = protocol;
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this.port = port;
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this.host = host;
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this.file = file;
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this.ref = ref;
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}
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public static synchronized void
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setURLStreamHandlerFactory(URLStreamHandlerFactory fac)
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{
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if (factory != null)
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throw new Error("URLStreamHandlerFactory already set");
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// Throw an exception if an extant security mgr precludes
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// setting the factory.
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SecurityManager s = System.getSecurityManager();
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if (s != null)
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s.checkSetFactory();
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factory = fac;
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}
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public String toExternalForm()
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{
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// Identical to toString().
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return handler.toExternalForm(this);
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}
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public String toString()
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{
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// Identical to toExternalForm().
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return handler.toExternalForm(this);
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}
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private URLStreamHandler setURLStreamHandler(String protocol)
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{
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URLStreamHandler handler;
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// See if a handler has been cached for this protocol.
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if ((handler = (URLStreamHandler) handlers.get(protocol)) != null)
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return handler;
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// If a non-default factory has been set, use it to find the protocol.
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if (factory != null)
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handler = factory.createURLStreamHandler(protocol);
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// Non-default factory may have returned null or a factory wasn't set.
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// Use the default search algorithm to find a handler for this protocol.
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if (handler == null)
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{
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// Get the list of packages to check and append our default handler
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// to it, along with the JDK specified default as a last resort.
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// Except in very unusual environments the JDK specified one shouldn't
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// ever be needed (or available).
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String propVal = System.getProperty("java.protocol.handler.pkgs");
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propVal = (propVal == null) ? "" : (propVal + "|");
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propVal = propVal + "gnu.gcj.protocol|sun.net.www.protocol";
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StringTokenizer pkgPrefix = new StringTokenizer(propVal, "|");
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do
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{
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String facName = pkgPrefix.nextToken() + "." + protocol +
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".Handler";
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try
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{
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handler =
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(URLStreamHandler) Class.forName(facName).newInstance();
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}
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catch (Exception e)
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{
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// Can't instantiate; handler still null, go on to next element.
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}
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} while ((handler == null ||
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! (handler instanceof URLStreamHandler)) &&
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pkgPrefix.hasMoreTokens());
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}
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// Update the hashtable with the new protocol handler.
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if (handler != null)
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if (handler instanceof URLStreamHandler)
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handlers.put(protocol, handler);
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else
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handler = null;
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return handler;
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}
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}
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