1/*
2 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. 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.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package com.sun.net.httpserver.spi;
27
28import java.io.IOException;
29import java.net.*;
30import java.security.AccessController;
31import java.security.PrivilegedAction;
32import java.util.Iterator;
33import java.util.ServiceLoader;
34import java.util.ServiceConfigurationError;
35import com.sun.net.httpserver.*;
36
37/**
38 * Service provider class for HttpServer.
39 * Sub-classes of HttpServerProvider provide an implementation of
40 * {@link HttpServer} and associated classes. Applications do not normally use
41 * this class. See {@link #provider()} for how providers are found and loaded.
42 */
43public abstract class HttpServerProvider {
44
45    /**
46     * creates a HttpServer from this provider
47     *
48     * @param  addr
49     *         the address to bind to. May be {@code null}
50     *
51     * @param  backlog
52     *         the socket backlog. A value of {@code zero} means the systems default
53     */
54    public abstract HttpServer createHttpServer(InetSocketAddress addr,
55                                                int backlog)
56        throws IOException;
57
58    /**
59     * creates a HttpsServer from this provider
60     *
61     * @param  addr
62     *         the address to bind to. May be {@code null}
63     *
64     * @param  backlog
65     *         the socket backlog. A value of {@code zero} means the systems default
66     */
67    public abstract HttpsServer createHttpsServer(InetSocketAddress addr,
68                                                  int backlog)
69        throws IOException;
70
71    private static final Object lock = new Object();
72    private static HttpServerProvider provider = null;
73
74    /**
75     * Initializes a new instance of this class.
76     *
77     * @throws  SecurityException
78     *          If a security manager has been installed and it denies
79     *          {@link RuntimePermission}{@code ("httpServerProvider")}
80     */
81    protected HttpServerProvider() {
82        SecurityManager sm = System.getSecurityManager();
83        if (sm != null)
84            sm.checkPermission(new RuntimePermission("httpServerProvider"));
85    }
86
87    private static boolean loadProviderFromProperty() {
88        String cn = System.getProperty("com.sun.net.httpserver.HttpServerProvider");
89        if (cn == null)
90            return false;
91        try {
92            @SuppressWarnings("deprecation")
93            Object o = Class.forName(cn, true,
94                                     ClassLoader.getSystemClassLoader()).newInstance();
95            provider = (HttpServerProvider)o;
96            return true;
97        } catch (ClassNotFoundException |
98                 IllegalAccessException |
99                 InstantiationException |
100                 SecurityException x) {
101            throw new ServiceConfigurationError(null, x);
102        }
103    }
104
105    private static boolean loadProviderAsService() {
106        Iterator<HttpServerProvider> i =
107            ServiceLoader.load(HttpServerProvider.class,
108                               ClassLoader.getSystemClassLoader())
109                .iterator();
110        for (;;) {
111            try {
112                if (!i.hasNext())
113                    return false;
114                provider = i.next();
115                return true;
116            } catch (ServiceConfigurationError sce) {
117                if (sce.getCause() instanceof SecurityException) {
118                    // Ignore the security exception, try the next provider
119                    continue;
120                }
121                throw sce;
122            }
123        }
124    }
125
126    /**
127     * Returns the system wide default HttpServerProvider for this invocation of
128     * the Java virtual machine.
129     *
130     * <p> The first invocation of this method locates the default provider
131     * object as follows: </p>
132     *
133     * <ol>
134     *
135     *   <li><p> If the system property
136     *   {@code com.sun.net.httpserver.HttpServerProvider} is defined then it
137     *   is taken to be the fully-qualified name of a concrete provider class.
138     *   The class is loaded and instantiated; if this process fails then an
139     *   unspecified unchecked error or exception is thrown.  </p></li>
140     *
141     *   <li><p> If a provider class has been installed in a jar file that is
142     *   visible to the system class loader, and that jar file contains a
143     *   provider-configuration file named
144     *   {@code com.sun.net.httpserver.HttpServerProvider} in the resource
145     *   directory {@code META-INF/services}, then the first class name
146     *   specified in that file is taken.  The class is loaded and
147     *   instantiated; if this process fails then an unspecified unchecked error
148     *   or exception is thrown.  </p></li>
149     *
150     *   <li><p> Finally, if no provider has been specified by any of the above
151     *   means then the system-default provider class is instantiated and the
152     *   result is returned.  </p></li>
153     *
154     * </ol>
155     *
156     * <p> Subsequent invocations of this method return the provider that was
157     * returned by the first invocation.  </p>
158     *
159     * @return  The system-wide default HttpServerProvider
160     */
161    public static HttpServerProvider provider () {
162        synchronized (lock) {
163            if (provider != null)
164                return provider;
165            return (HttpServerProvider)AccessController
166                .doPrivileged(new PrivilegedAction<Object>() {
167                        public Object run() {
168                            if (loadProviderFromProperty())
169                                return provider;
170                            if (loadProviderAsService())
171                                return provider;
172                            provider = new sun.net.httpserver.DefaultHttpServerProvider();
173                            return provider;
174                        }
175                    });
176        }
177    }
178
179}
180