166 lines
6.2 KiB
Java
166 lines
6.2 KiB
Java
/*
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* Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.net;
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import java.io.IOException;
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import java.util.List;
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import sun.security.util.SecurityConstants;
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/**
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* Selects the proxy server to use, if any, when connecting to the
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* network resource referenced by a URL. A proxy selector is a
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* concrete sub-class of this class and is registered by invoking the
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* {@link java.net.ProxySelector#setDefault setDefault} method. The
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* currently registered proxy selector can be retrieved by calling
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* {@link java.net.ProxySelector#getDefault getDefault} method.
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*
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* <p> When a proxy selector is registered, for instance, a subclass
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* of URLConnection class should call the {@link #select select}
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* method for each URL request so that the proxy selector can decide
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* if a direct, or proxied connection should be used. The {@link
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* #select select} method returns an iterator over a collection with
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* the preferred connection approach.
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*
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* <p> If a connection cannot be established to a proxy (PROXY or
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* SOCKS) servers then the caller should call the proxy selector's
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* {@link #connectFailed connectFailed} method to notify the proxy
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* selector that the proxy server is unavailable. </p>
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*
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* <P>The default proxy selector does enforce a
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* <a href="doc-files/net-properties.html#Proxies">set of System Properties</a>
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* related to proxy settings.</P>
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*
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* @author Yingxian Wang
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* @author Jean-Christophe Collet
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* @since 1.5
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*/
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public abstract class ProxySelector {
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/**
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* The system wide proxy selector that selects the proxy server to
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* use, if any, when connecting to a remote object referenced by
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* an URL.
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*
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* @see #setDefault(ProxySelector)
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*/
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private static ProxySelector theProxySelector;
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static {
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try {
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Class<?> c = Class.forName("sun.net.spi.DefaultProxySelector");
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if (c != null && ProxySelector.class.isAssignableFrom(c)) {
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theProxySelector = (ProxySelector) c.newInstance();
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}
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} catch (Exception e) {
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theProxySelector = null;
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}
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}
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/**
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* Gets the system-wide proxy selector.
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*
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* @throws SecurityException
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* If a security manager has been installed and it denies
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* {@link NetPermission}{@code ("getProxySelector")}
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* @see #setDefault(ProxySelector)
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* @return the system-wide {@code ProxySelector}
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* @since 1.5
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*/
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public static ProxySelector getDefault() {
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SecurityManager sm = System.getSecurityManager();
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if (sm != null) {
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sm.checkPermission(SecurityConstants.GET_PROXYSELECTOR_PERMISSION);
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}
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return theProxySelector;
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}
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/**
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* Sets (or unsets) the system-wide proxy selector.
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*
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* Note: non-standard protocol handlers may ignore this setting.
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*
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* @param ps The HTTP proxy selector, or
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* {@code null} to unset the proxy selector.
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*
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* @throws SecurityException
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* If a security manager has been installed and it denies
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* {@link NetPermission}{@code ("setProxySelector")}
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*
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* @see #getDefault()
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* @since 1.5
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*/
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public static void setDefault(ProxySelector ps) {
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SecurityManager sm = System.getSecurityManager();
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if (sm != null) {
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sm.checkPermission(SecurityConstants.SET_PROXYSELECTOR_PERMISSION);
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}
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theProxySelector = ps;
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}
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/**
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* Selects all the applicable proxies based on the protocol to
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* access the resource with and a destination address to access
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* the resource at.
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* The format of the URI is defined as follow:
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* <UL>
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* <LI>http URI for http connections</LI>
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* <LI>https URI for https connections
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* <LI>{@code socket://host:port}<br>
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* for tcp client sockets connections</LI>
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* </UL>
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*
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* @param uri
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* The URI that a connection is required to
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*
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* @return a List of Proxies. Each element in the
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* the List is of type
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* {@link java.net.Proxy Proxy};
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* when no proxy is available, the list will
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* contain one element of type
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* {@link java.net.Proxy Proxy}
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* that represents a direct connection.
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* @throws IllegalArgumentException if the argument is null
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*/
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public abstract List<Proxy> select(URI uri);
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/**
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* Called to indicate that a connection could not be established
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* to a proxy/socks server. An implementation of this method can
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* temporarily remove the proxies or reorder the sequence of
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* proxies returned by {@link #select(URI)}, using the address
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* and the IOException caught when trying to connect.
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*
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* @param uri
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* The URI that the proxy at sa failed to serve.
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* @param sa
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* The socket address of the proxy/SOCKS server
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*
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* @param ioe
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* The I/O exception thrown when the connect failed.
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* @throws IllegalArgumentException if either argument is null
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*/
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public abstract void connectFailed(URI uri, SocketAddress sa, IOException ioe);
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}
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