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    1   package org.apache.bcel.util;
    2
    3   /* ====================================================================
    4    * The Apache Software License, Version 1.1
    5    *
    6    * Copyright (c) 2001 The Apache Software Foundation.  All rights
    7    * reserved.
    8    *
    9    * Redistribution and use in source and binary forms, with or without
    10   * modification, are permitted provided that the following conditions
    11   * are met:
    12   *
    13   * 1. Redistributions of source code must retain the above copyright
    14   *    notice, this list of conditions and the following disclaimer.
    15   *
    16   * 2. Redistributions in binary form must reproduce the above copyright
    17   *    notice, this list of conditions and the following disclaimer in
    18   *    the documentation and/or other materials provided with the
    19   *    distribution.
    20   *
    21   * 3. The end-user documentation included with the redistribution,
    22   *    if any, must include the following acknowledgment:
    23   *       "This product includes software developed by the
    24   *        Apache Software Foundation (http://www.apache.org/)."
    25   *    Alternately, this acknowledgment may appear in the software itself,
    26   *    if and wherever such third-party acknowledgments normally appear.
    27   *
    28   * 4. The names "Apache" and "Apache Software Foundation" and
    29   *    "Apache BCEL" must not be used to endorse or promote products
    30   *    derived from this software without prior written permission. For
    31   *    written permission, please contact apache@apache.org.
    32   *
    33   * 5. Products derived from this software may not be called "Apache",
    34   *    "Apache BCEL", nor may "Apache" appear in their name, without
    35   *    prior written permission of the Apache Software Foundation.
    36   *
    37   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
    38   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
    39   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    40   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
    41   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    42   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    43   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
    44   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
    45   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
    46   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
    47   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    48   * SUCH DAMAGE.
    49   * ====================================================================
    50   *
    51   * This software consists of voluntary contributions made by many
    52   * individuals on behalf of the Apache Software Foundation.  For more
    53   * information on the Apache Software Foundation, please see
    54   * <http://www.apache.org/>;.
    55   */
    56
    57  import java.lang.reflect.*;
    58
    59  /***
    60   * Java interpreter replacement, i.e., wrapper that uses its own ClassLoader
    61   * to modify/generate classes as they're requested. You can take this as a template
    62   * for your own applications.<br>
    63   * Call this wrapper with
    64   * <pre>java org.apache.bcel.util.JavaWrapper <real.class.name> [arguments]</pre>
    65   * <p>
    66   * To use your own class loader you can set the "bcel.classloader" system property
    67   * which defaults to "org.apache.bcel.util.ClassLoader", e.g., with
    68   * <pre>java org.apache.bcel.util.JavaWrapper -Dbcel.classloader=foo.MyLoader <real.class.name> [arguments]</pre>
    69   * </p>
    70   *
    71   * @version $Id: JavaWrapper.java,v 1.1.1.1 2001/10/29 20:00:30 jvanzyl Exp $
    72   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
    73   * @see ClassLoader
    74   */
    75  public class JavaWrapper {
    76    private java.lang.ClassLoader loader;
    77
    78    private static java.lang.ClassLoader getClassLoader() {
    79      String s = System.getProperty("bcel.classloader");
    80
    81      if((s == null) || "".equals(s))
    82        s = "org.apache.bcel.util.ClassLoader";
    83
    84      try {
    85        return (java.lang.ClassLoader)Class.forName(s).newInstance();
    86      } catch(Exception e) {
    87        throw new RuntimeException(e.toString());
    88      }
    89    }
    90
    91    public JavaWrapper(java.lang.ClassLoader loader) {
    92      this.loader = loader;
    93    }
    94
    95    public JavaWrapper() {
    96      this(getClassLoader());
    97    }
    98
    99    /*** Runs the main method of the given class with the arguments passed in argv
    100    *
    101    * @param class_name the fully qualified class name
    102    * @param argv the arguments just as you would pass them directly
    103    */
    104   public void runMain(String class_name, String[] argv) throws ClassNotFoundException
    105   {
    106     Class   cl    = loader.loadClass(class_name);
    107     Method method = null;
    108
    109     try {
    110       method = cl.getMethod("main",  new Class[] { argv.getClass() });
    111
    112       /* Method main is sane ?
    113        */
    114       int   m = method.getModifiers();
    115       Class r = method.getReturnType();
    116
    117       if(!(Modifier.isPublic(m) && Modifier.isStatic(m)) ||
    118 	 Modifier.isAbstract(m) || (r != Void.TYPE))
    119 	throw new NoSuchMethodException();
    120     } catch(NoSuchMethodException no) {
    121       System.out.println("In class " + class_name +
    122 			 ": public static void main(String[] argv) is not defined");
    123       return;
    124     }
    125
    126     try {
    127       method.invoke(null, new Object[] { argv });
    128     } catch(Exception ex) {
    129       ex.printStackTrace();
    130     }
    131   }
    132
    133   /*** Default main method used as wrapper, expects the fully qualified class name
    134    * of the real class as the first argument.
    135    */
    136   public static void main(String[] argv) throws Exception {
    137     /* Expects class name as first argument, other arguments are by-passed.
    138      */
    139     if(argv.length == 0) {
    140       System.out.println("Missing class name.");
    141       return;
    142     }
    143
    144     String class_name = argv[0];
    145     String[] new_argv = new String[argv.length - 1];
    146     System.arraycopy(argv, 1, new_argv, 0, new_argv.length);
    147
    148     JavaWrapper wrapper = new JavaWrapper();
    149     wrapper.runMain(class_name, new_argv);
    150   }
    151 }
    152

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