1 /*
   2  * Copyright (c) 2015, 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 java.net.spi;
  27 
  28 import java.net.URLStreamHandlerFactory;
  29 
  30 /**
  31  * URL stream handler service-provider class.
  32  *
  33  * <p> A URL stream handler provider is a concrete subclass of this class that
  34  * has a zero-argument constructor. URL stream handler providers may be
  35  * installed in an instance of the Java platform by adding them to the
  36  * application class path.
  37  *
  38  * <p> A URL stream handler provider identifies itself with a
  39  * provider-configuration file named java.net.spi.URLStreamHandlerProvider in
  40  * the resource directory META-INF/services. The file should contain a list of
  41  * fully-qualified concrete URL stream handler provider class names, one per
  42  * line.
  43  *
  44  * <p> URL stream handler providers are located at runtime, as specified in the
  45  * {@linkplain java.net.URL#URL(String,String,int,String) URL constructor}.
  46  *
  47  * @since 9
  48  */
  49 public abstract class URLStreamHandlerProvider
  50     implements URLStreamHandlerFactory
  51 {
  52     private static Void checkPermission() {
  53         SecurityManager sm = System.getSecurityManager();
  54         if (sm != null)
  55             sm.checkPermission(new RuntimePermission("setFactory"));
  56         return null;
  57     }
  58     private URLStreamHandlerProvider(Void ignore) { }
  59 
  60     /**
  61      * Initializes a new URL stream handler provider.
  62      *
  63      * @throws  SecurityException
  64      *          If a security manager has been installed and it denies
  65      *          {@link RuntimePermission}{@code ("setFactory")}.
  66      */
  67     protected URLStreamHandlerProvider() {
  68         this(checkPermission());
  69     }
  70 }