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

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