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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    * 
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   * 
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  import java.io.File;
19  import java.io.FileInputStream;
20  import java.io.FileNotFoundException;
21  import java.lang.reflect.Method;
22  import java.net.MalformedURLException;
23  import java.net.URL;
24  import java.net.URLClassLoader;
25  import java.net.URLDecoder;
26  import java.util.ArrayList;
27  import java.util.Properties;
28  import java.util.StringTokenizer;
29  
30  /**
31   * This class is used as a wrapper for loading the
32   * org.apache.commons.launcher.Launcher class and invoking its
33   * <code>main(String[])</code> method. This particular
34   * class is primary used by the Windows 95, 98, ME, and 2000 platforms to
35   * overcome the difficulty of putting a jar file directly into the JVM's
36   * classpath when using batch scripts on these platforms.
37   * <p>
38   * Specifically, the problem on thse platforms is when Windows uses the PATH
39   * environment variable to find and run a batch script, %0 will resolve
40   * incorrectly in that batch script.
41   * <p>
42   * The way to work around this Windows limitation is to do the following:
43   * <ol>
44   * <li>Put this class' class file - LauncherBootstrap.class - in the same
45   * directory as the batch script. Do not put this class file in a jar file.
46   * <li>Put the jar file containing the launcher's classes in the same
47   * directory as the batch script and this class' class file. Be sure that
48   * that the jar file is named "commons-launcher.jar".
49   * <li>Make the Java command in the batch script invoke Java use the following
50   * classpath arguments. Be sure to include the quotes to ensure that paths
51   * containing spaces are handled properly:
52   * <code>-classpath %0\..;"%PATH%"</code>
53   * </ol>
54   *
55   * @author Patrick Luby
56   */
57  public class LauncherBootstrap {
58  
59      //---------------------------------------------------------- Static Fields
60  
61      /**
62       * Ant classpath property name
63       */
64      public final static String ANT_CLASSPATH_PROP_NAME = "ant.class.path";
65  
66      /**
67       * Jar file name
68       */
69      public final static String LAUNCHER_JAR_FILE_NAME = "commons-launcher.jar";
70  
71      /**
72       * Properties file name
73       */
74      public final static String LAUNCHER_PROPS_FILE_NAME = "launcher.properties";
75  
76      /**
77       * Class name to load
78       */
79      public final static String LAUNCHER_MAIN_CLASS_NAME = "org.apache.commons.launcher.Launcher";
80  
81      /**
82       * Cached Laucher class.
83       */
84      private static Class launcherClass = null;
85  
86      //---------------------------------------------------------- Static Methods
87  
88      /**
89       * The main method.
90       *
91       * @param args command line arguments
92       */
93      public static void main(String[] args) {
94  
95          try {
96  
97              // Try to find the LAUNCHER_JAR_FILE_NAME file in the class
98              // loader's and JVM's classpath.
99              URL coreURL = LauncherBootstrap.class.getResource("/" + LauncherBootstrap.LAUNCHER_JAR_FILE_NAME);
100             if (coreURL == null)
101                 throw new FileNotFoundException(LauncherBootstrap.LAUNCHER_JAR_FILE_NAME);
102 
103             // Coerce the coreURL's directory into a file
104             File coreDir = new File(URLDecoder.decode(coreURL.getFile())).getCanonicalFile().getParentFile();
105 
106             // Try to find the LAUNCHER_PROPS_FILE_NAME file in the same
107             // directory as this class
108             File propsFile = new File(coreDir, LauncherBootstrap.LAUNCHER_PROPS_FILE_NAME);
109             if (!propsFile.canRead())
110                 throw new FileNotFoundException(propsFile.getPath());
111 
112             // Load the properties in the LAUNCHER_PROPS_FILE_NAME 
113             Properties props = new Properties();
114             FileInputStream fis = new FileInputStream(propsFile);
115             props.load(fis);
116             fis.close();
117 
118             // Create a class loader that contains the Launcher, Ant, and
119             // JAXP classes.
120             URL[] antURLs = LauncherBootstrap.fileListToURLs((String)props.get(LauncherBootstrap.ANT_CLASSPATH_PROP_NAME));
121             URL[] urls = new URL[1 + antURLs.length];
122             urls[0] = coreURL;
123             for (int i = 0; i < antURLs.length; i++)
124                 urls[i + 1] = antURLs[i];
125             ClassLoader parentLoader = Thread.currentThread().getContextClassLoader();
126             URLClassLoader loader = null;
127             if (parentLoader != null)
128                 loader = new URLClassLoader(urls, parentLoader);
129             else
130                 loader = new URLClassLoader(urls);
131 
132             // Load the LAUNCHER_MAIN_CLASS_NAME class
133             launcherClass = loader.loadClass(LAUNCHER_MAIN_CLASS_NAME);
134 
135             // Get the LAUNCHER_MAIN_CLASS_NAME class' getLocalizedString()
136             // method as we need it for printing the usage statement
137             Method getLocalizedStringMethod = launcherClass.getDeclaredMethod("getLocalizedString", new Class[]{ String.class });
138 
139             // Invoke the LAUNCHER_MAIN_CLASS_NAME class' start() method.
140             // If the ant.class.path property is not set correctly in the 
141             // LAUNCHER_PROPS_FILE_NAME, this will throw an exception.
142             Method startMethod = launcherClass.getDeclaredMethod("start", new Class[]{ String[].class });
143             int returnValue = ((Integer)startMethod.invoke(null, new Object[]{ args })).intValue();
144             // Always exit cleanly after invoking the start() method
145             System.exit(returnValue);
146 
147        } catch (Throwable t) {
148 
149            t.printStackTrace();
150            System.exit(1);
151 
152         }
153 
154     }
155 
156     /**
157      * Convert a ":" separated list of URL file fragments into an array of URL
158      * objects. Note that any all URL file fragments must conform to the format
159      * required by the "file" parameter in the
160      * {@link URL(String, String, String)} constructor.
161      *
162      * @param fileList the ":" delimited list of URL file fragments to be
163      *  converted
164      * @return an array of URL objects
165      * @throws MalformedURLException if the fileList parameter contains any
166      *  malformed URLs
167      */
168     private static URL[] fileListToURLs(String fileList)
169         throws MalformedURLException
170     {
171 
172         if (fileList == null || "".equals(fileList))
173             return new URL[0];
174 
175         // Parse the path string
176         ArrayList list = new ArrayList();
177         StringTokenizer tokenizer = new StringTokenizer(fileList, ":");
178         URL bootstrapURL = LauncherBootstrap.class.getResource("/" + LauncherBootstrap.class.getName() + ".class");
179         while (tokenizer.hasMoreTokens())
180             list.add(new URL(bootstrapURL, tokenizer.nextToken()));
181 
182         return (URL[])list.toArray(new URL[list.size()]);
183 
184     }
185 
186 }