1 /*
   2  * Copyright (c) 1997, 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 
  26 package com.sun.xml.internal.org.jvnet.mimepull;
  27 
  28 import java.io.BufferedReader;
  29 import java.io.IOException;
  30 import java.io.InputStream;
  31 import java.io.InputStreamReader;
  32 import java.util.logging.Level;
  33 import java.util.logging.Logger;
  34 
  35 class FactoryFinder {
  36 
  37     private static ClassLoader cl = FactoryFinder.class.getClassLoader();
  38 
  39     static Object find(String factoryId) throws ClassNotFoundException,
  40             InstantiationException, IllegalAccessException {
  41         String systemProp = System.getProperty(factoryId);
  42         if (systemProp != null) {
  43             return newInstance(systemProp);
  44         }
  45 
  46         String providerName = findJarServiceProviderName(factoryId);
  47         if (providerName != null && providerName.trim().length() > 0) {
  48             return newInstance(providerName);
  49         }
  50 
  51         return null;
  52     }
  53 
  54     static Object newInstance(String className) throws ClassNotFoundException,
  55             InstantiationException, IllegalAccessException {
  56         Class providerClass = cl.loadClass(className);
  57         Object instance = providerClass.newInstance();
  58         return instance;
  59     }
  60 
  61     private static String findJarServiceProviderName(String factoryId) {
  62         String serviceId = "META-INF/services/" + factoryId;
  63         InputStream is;
  64         is = cl.getResourceAsStream(serviceId);
  65 
  66         if (is == null) {
  67             return null;
  68         }
  69 
  70         String factoryClassName;
  71         BufferedReader rd = null;
  72         try {
  73             try {
  74                 rd = new BufferedReader(new InputStreamReader(is, "UTF-8"));
  75             } catch (java.io.UnsupportedEncodingException e) {
  76                 rd = new BufferedReader(new InputStreamReader(is));
  77             }
  78             try {
  79                 factoryClassName = rd.readLine();
  80             } catch (IOException x) {
  81                 return null;
  82             }
  83         } finally {
  84             if (rd != null) {
  85                 try {
  86                     rd.close();
  87                 } catch (IOException ex) {
  88                     Logger.getLogger(FactoryFinder.class.getName()).log(Level.INFO, null, ex);
  89                 }
  90             }
  91         }
  92 
  93         return factoryClassName;
  94     }
  95 
  96 }