javaclass.java

该开源工具主要用于class文件的操作

package org.apache.bcel.classfile;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache BCEL", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import  org.apache.bcel.Constants;
import  org.apache.bcel.Repository;
import  java.io.*;
import  java.util.StringTokenizer;

/**
 * Represents a Java class, i.e., the data structures, constant pool,
 * fields, methods and commands contained in a Java .class file.
 * See <a href="ftp://java.sun.com/docs/specs/">JVM 
 * specification</a> for details.
 *
 * @version $Id: JavaClass.java,v 1.1.1.1 2001/10/29 20:00:01 jvanzyl Exp $
 * @author  <A HREF="mailto:[e-mail]">M. Dahm</A>
 */
public class JavaClass extends AccessFlags implements Cloneable, Node {
  private String       file_name;
  private String       package_name;
  private String       source_file_name = "<Unknown>";
  private int          class_name_index;
  private int          superclass_name_index;
  private String       class_name;
  private String       superclass_name;
  private int          major, minor;  // Compiler version
  private ConstantPool constant_pool; // Constant pool
  private int[]        interfaces;    // implemented interfaces
  private String[]     interface_names;
  private Field[]      fields;        // Fields, i.e., variables of class
  private Method[]     methods;       // methods defined in the class
  private Attribute[]  attributes;    // attributes defined in the class
  private byte         source = HEAP; // Generated in memory

  public static final byte HEAP = 1;
  public static final byte FILE = 2;
  public static final byte ZIP  = 3;

  static boolean debug = false; // Debugging on/off
  static char    sep   = '/';   // directory separator

  /**
   * Constructor gets all contents as arguments.
   *
   * @param class_name Class name
   * @param superclass_name Superclass name
   * @param file_name File name
   * @param major Major compiler version
   * @param minor Minor compiler version
   * @param access_flags Access rights defined by bit flags
   * @param constant_pool Array of constants
   * @param interfaces Implemented interfaces
   * @param fields Class fields
   * @param methods Class methods
   * @param attributes Class attributes
   * @param source Read from file or generated in memory?
   */
  public JavaClass(int        class_name_index,
		   int        superclass_name_index,
		   String     file_name,
		   int        major,
		   int        minor,
		   int        access_flags,
		   ConstantPool constant_pool,
		   int[]      interfaces,
		   Field[]      fields,
		   Method[]     methods,
		   Attribute[]  attributes,
		   byte          source)
  {
    if(interfaces == null) // Allowed for backward compatibility
      interfaces = new int[0];
    if(attributes == null)
      this.attributes = new Attribute[0];
    if(fields == null)
      fields = new Field[0];
    if(methods == null)
      methods = new Method[0];

    this.class_name_index      = class_name_index;
    this.superclass_name_index = superclass_name_index;
    this.file_name             = file_name;
    this.major                 = major;
    this.minor                 = minor;
    this.access_flags          = access_flags;
    this.constant_pool         = constant_pool;
    this.interfaces            = interfaces;
    this.fields                = fields;
    this.methods               = methods;
    this.attributes            = attributes;
    this.source                = source;

    // Get source file name if available
    for(int i=0; i < attributes.length; i++) {
      if(attributes[i] instanceof SourceFile) {
	source_file_name = ((SourceFile)attributes[i]).getSourceFileName();
	break;
      }
    }
	
    // Get class name and superclass name
    ConstantUtf8  name;

    /* According to the specification the following entries must be of type
     * `ConstantClass' but we check that anyway via the 
     * `ConstPool.getConstant' method.
     */
    class_name = constant_pool.getConstantString(class_name_index, 
						 Constants.CONSTANT_Class);
    class_name = Utility.compactClassName(class_name, false);

    int index = class_name.lastIndexOf('.');
    if(index < 0)
      package_name = "";
    else
      package_name = class_name.substring(0, index);

    if(superclass_name_index > 0) { // May be zero -> class is java.lang.Object
      superclass_name = constant_pool.getConstantString(superclass_name_index,
							Constants.CONSTANT_Class);
      superclass_name = Utility.compactClassName(superclass_name, false);
    }
    else
      superclass_name = "java.lang.Object";    

    interface_names = new String[interfaces.length];
    for(int i=0; i < interfaces.length; i++) {
      String str = constant_pool.getConstantString(interfaces[i], Constants.CONSTANT_Class);
      interface_names[i] = Utility.compactClassName(str, false);
    }
  }

  /**
   * Constructor gets all contents as arguments.
   *
   * @param class_name Class name
   * @param superclass_name Superclass name
   * @param file_name File name
   * @param major Major compiler version
   * @param minor Minor compiler version
   * @param access_flags Access rights defined by bit flags
   * @param constant_pool Array of constants
   * @param interfaces Implemented interfaces
   * @param fields Class fields
   * @param methods Class methods
   * @param attributes Class attributes
   */
  public JavaClass(int        class_name_index,
		   int        superclass_name_index,
		   String     file_name,
		   int        major,
		   int        minor,
		   int        access_flags,
		   ConstantPool constant_pool,
		   int[]      interfaces,
		   Field[]      fields,
		   Method[]     methods,
		   Attribute[]  attributes) {
    this(class_name_index, superclass_name_index, file_name, major, minor, access_flags,
	 constant_pool, interfaces, fields, methods, attributes, HEAP);
  }

      
  /**
   * Called by objects that are traversing the nodes of the tree implicitely
   * defined by the contents of a Java class. I.e., the hierarchy of methods,
   * fields, attributes, etc. spawns a tree of objects.
   *
   * @param v Visitor object
   */
  public void accept(Visitor v) {
    v.visitJavaClass(this);
  }

  /* Print debug information depending on `JavaClass.debug'
   */
  static final void Debug(String str) {
    if(debug)
      System.out.println(str);
  }

  /** 
   * Dump class to a file.
   *
   * @param file Output file
   * @throw IOException
   */
  public void dump(File file) throws IOException
  {
    String parent = file.getParent();

    if(parent != null) {
      File dir = new File(parent);
      
      if(dir != null)
	dir.mkdirs();
    }

    dump(new DataOutputStream(new FileOutputStream(file)));
  }

  /** 
   * Dump class to a file named file_name.
   *
   * @param file_name Output file name
   * @exception IOException
   */
  public void dump(String file_name) throws IOException
  {
    dump(new File(file_name));
  }

  /**
   * @return class in binary format
   */
  public byte[] getBytes() {
    ByteArrayOutputStream s  = new ByteArrayOutputStream();
    DataOutputStream      ds = new DataOutputStream(s);

    try {
      dump(ds);
      ds.close();
    } catch(IOException e) { e.printStackTrace(); }

    return s.toByteArray();
  }

  /**
   * Dump Java class to output stream in binary format.
   *
   * @param file Output stream
   * @exception IOException
   */
  public void dump(OutputStream file) throws IOException {
    dump(new DataOutputStream(file));
  }

  /**
   * Dump Java class to output stream in binary format.
   *
   * @param file Output stream
   * @exception IOException
   */
  public void dump(DataOutputStream file) throws IOException
  {
    file.writeInt(0xcafebabe);
    file.writeShort(minor);
    file.writeShort(major);

    constant_pool.dump(file);
	
    file.writeShort(access_flags);
    file.writeShort(class_name_index);