1 /*
2 * Copyright 2003-2006 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package java.net;
27
28 import java.io.IOException;
29 import java.util.List;
30 import sun.security.util.SecurityConstants;
31
32 /**
33 * Selects the proxy server to use, if any, when connecting to the
34 * network resource referenced by a URL. A proxy selector is a
35 * concrete sub-class of this class and is registered by invoking the
36 * {@link java.net.ProxySelector#setDefault setDefault} method. The
37 * currently registered proxy selector can be retrieved by calling
38 * {@link java.net.ProxySelector#getDefault getDefault} method.
39 *
40 * <p> When a proxy selector is registered, for instance, a subclass
41 * of URLConnection class should call the {@link #select select}
42 * method for each URL request so that the proxy selector can decide
43 * if a direct, or proxied connection should be used. The {@link
44 * #select select} method returns an iterator over a collection with
45 * the preferred connection approach.
46 *
47 * <p> If a connection cannot be established to a proxy (PROXY or
48 * SOCKS) servers then the caller should call the proxy selector's
49 * {@link #connectFailed connectFailed} method to notify the proxy
50 * selector that the proxy server is unavailable. </p>
51 *
52 * <P>The default proxy selector does enforce a
53 * <a href="doc-files/net-properties.html#Proxies">set of System Properties</a>
54 * related to proxy settings.</P>
55 *
56 * @author Yingxian Wang
57 * @author Jean-Christophe Collet
58 * @since 1.5
59 */
60 public abstract class ProxySelector {
61 /**
62 * The system wide proxy selector that selects the proxy server to
63 * use, if any, when connecting to a remote object referenced by
64 * an URL.
65 *
66 * @see #setDefault(ProxySelector)
67 */
68 private static ProxySelector theProxySelector;
69
70 static {
71 try {
72 Class c = Class.forName("sun.net.spi.DefaultProxySelector");
73 if (c != null && ProxySelector.class.isAssignableFrom(c)) {
74 theProxySelector = (ProxySelector) c.newInstance();
75 }
76 } catch (Exception e) {
77 theProxySelector = null;
78 }
79 }
80
81 /**
82 * Gets the system-wide proxy selector.
83 *
84 * @throws SecurityException
85 * If a security manager has been installed and it denies
86 * {@link NetPermission}<tt>("getProxySelector")</tt>
87 * @see #setDefault(ProxySelector)
88 * @return the system-wide <code>ProxySelector</code>
89 * @since 1.5
90 */
91 public static ProxySelector getDefault() {
92 SecurityManager sm = System.getSecurityManager();
93 if (sm != null) {
94 sm.checkPermission(SecurityConstants.GET_PROXYSELECTOR_PERMISSION);
95 }
96 return theProxySelector;
97 }
98
99 /**
100 * Sets (or unsets) the system-wide proxy selector.
101 *
102 * Note: non-standard protocol handlers may ignore this setting.
103 *
104 * @param ps The HTTP proxy selector, or
105 * <code>null</code> to unset the proxy selector.
106 *
107 * @throws SecurityException
108 * If a security manager has been installed and it denies
109 * {@link NetPermission}<tt>("setProxySelector")</tt>
110 *
111 * @see #getDefault()
112 * @since 1.5
113 */
114 public static void setDefault(ProxySelector ps) {
115 SecurityManager sm = System.getSecurityManager();
116 if (sm != null) {
117 sm.checkPermission(SecurityConstants.SET_PROXYSELECTOR_PERMISSION);
118 }
119 theProxySelector = ps;
120 }
121
122 /**
123 * Selects all the applicable proxies based on the protocol to
124 * access the resource with and a destination address to access
125 * the resource at.
126 * The format of the URI is defined as follow:
127 * <UL>
128 * <LI>http URI for http connections</LI>
129 * <LI>https URI for https connections
130 * <LI>ftp URI for ftp connections</LI>
131 * <LI><code>socket://host:port</code><br>
132 * for tcp client sockets connections</LI>
133 * </UL>
134 *
135 * @param uri
136 * The URI that a connection is required to
137 *
138 * @return a List of Proxies. Each element in the
139 * the List is of type
140 * {@link java.net.Proxy Proxy};
141 * when no proxy is available, the list will
142 * contain one element of type
143 * {@link java.net.Proxy Proxy}
144 * that represents a direct connection.
145 * @throws IllegalArgumentException if the argument is null
146 */
147 public abstract List<Proxy> select(URI uri);
148
149 /**
150 * Called to indicate that a connection could not be established
151 * to a proxy/socks server. An implementation of this method can
152 * temporarily remove the proxies or reorder the sequence of
153 * proxies returned by {@link #select(URI)}, using the address
154 * and the IOException caught when trying to connect.
155 *
156 * @param uri
157 * The URI that the proxy at sa failed to serve.
158 * @param sa
159 * The socket address of the proxy/SOCKS server
160 *
161 * @param ioe
162 * The I/O exception thrown when the connect failed.
163 * @throws IllegalArgumentException if either argument is null
164 */
165 public abstract void connectFailed(URI uri, SocketAddress sa, IOException ioe);
166 }
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