001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 * 
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 * 
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018import java.io.File;
019import java.io.FileInputStream;
020import java.io.FileNotFoundException;
021import java.lang.reflect.Method;
022import java.net.MalformedURLException;
023import java.net.URL;
024import java.net.URLClassLoader;
025import java.net.URLDecoder;
026import java.util.ArrayList;
027import java.util.Properties;
028import java.util.StringTokenizer;
029
030/**
031 * This class is used as a wrapper for loading the
032 * org.apache.commons.launcher.Launcher class and invoking its
033 * <code>main(String[])</code> method. This particular
034 * class is primary used by the Windows 95, 98, ME, and 2000 platforms to
035 * overcome the difficulty of putting a jar file directly into the JVM's
036 * classpath when using batch scripts on these platforms.
037 * <p>
038 * Specifically, the problem on thse platforms is when Windows uses the PATH
039 * environment variable to find and run a batch script, %0 will resolve
040 * incorrectly in that batch script.
041 * <p>
042 * The way to work around this Windows limitation is to do the following:
043 * <ol>
044 * <li>Put this class' class file - LauncherBootstrap.class - in the same
045 * directory as the batch script. Do not put this class file in a jar file.
046 * <li>Put the jar file containing the launcher's classes in the same
047 * directory as the batch script and this class' class file. Be sure that
048 * that the jar file is named "commons-launcher.jar".
049 * <li>Make the Java command in the batch script invoke Java use the following
050 * classpath arguments. Be sure to include the quotes to ensure that paths
051 * containing spaces are handled properly:
052 * <code>-classpath %0\..;"%PATH%"</code>
053 * </ol>
054 *
055 * @author Patrick Luby
056 */
057public class LauncherBootstrap {
058
059    //---------------------------------------------------------- Static Fields
060
061    /**
062     * Ant classpath property name
063     */
064    public final static String ANT_CLASSPATH_PROP_NAME = "ant.class.path";
065
066    /**
067     * Jar file name
068     */
069    public final static String LAUNCHER_JAR_FILE_NAME = "commons-launcher.jar";
070
071    /**
072     * Properties file name
073     */
074    public final static String LAUNCHER_PROPS_FILE_NAME = "launcher.properties";
075
076    /**
077     * Class name to load
078     */
079    public final static String LAUNCHER_MAIN_CLASS_NAME = "org.apache.commons.launcher.Launcher";
080
081    /**
082     * Cached Laucher class.
083     */
084    private static Class launcherClass = null;
085
086    //---------------------------------------------------------- Static Methods
087
088    /**
089     * The main method.
090     *
091     * @param args command line arguments
092     */
093    public static void main(String[] args) {
094
095        try {
096
097            // Try to find the LAUNCHER_JAR_FILE_NAME file in the class
098            // loader's and JVM's classpath.
099            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}