constantcp.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 java.io.*;
import  org.apache.bcel.Constants;

/** 
 * Abstract super class for Fieldref and Methodref constants.
 *
 * @version $Id: ConstantCP.java,v 1.1.1.1 2001/10/29 19:59:58 jvanzyl Exp $
 * @author  <A HREF="mailto:[e-mail]">M. Dahm</A>
 * @see     ConstantFieldref
 * @see     ConstantMethodref
 * @see     ConstantInterfaceMethodref
 */
public abstract class ConstantCP extends Constant {
  /** References to the constants containing the class and the field signature
   */
  protected int class_index, name_and_type_index; 

  /**
   * Initialize from another object.
   */
  public ConstantCP(ConstantCP c) {
    this(c.getTag(), c.getClassIndex(), c.getNameAndTypeIndex());
  }  
  
  /**
   * Initialize instance from file data.
   *
   * @param tag  Constant type tag
   * @param file Input stream
   * @throw IOException
   */
  ConstantCP(byte tag, DataInputStream file) throws IOException
  {
    this(tag, file.readUnsignedShort(), file.readUnsignedShort());
  }

  /**
   * @param class_index Reference to the class containing the field
   * @param name_and_type_index and the field signature
   */
  protected ConstantCP(byte tag, int class_index, 
		       int name_and_type_index) {
    super(tag);
    this.class_index         = class_index;
    this.name_and_type_index = name_and_type_index;
  }

  /** 
   * Dump constant field reference to file stream in binary format.
   *
   * @param file Output file stream
   * @throw IOException
   */ 
  public final void dump(DataOutputStream file) throws IOException
  {
    file.writeByte(tag);
    file.writeShort(class_index);
    file.writeShort(name_and_type_index);
  }    

  /**
   * @return Reference (index) to class this field or method belongs to.
   */  
  public final int getClassIndex()       { return class_index; }    

  /**
   * @return Reference (index) to signature of the field.
   */  
  public final int getNameAndTypeIndex() { return name_and_type_index; }    

  /**
   * @param class_index points to Constant_class 
   */
  public final void setClassIndex(int class_index) {
    this.class_index = class_index;
  }    

  /**
   * @return Class this field belongs to.
   */  
  public String getClass(ConstantPool cp) {
    return cp.constantToString(class_index, Constants.CONSTANT_Class);
  }

  /**
   * @param name_and_type_index points to Constant_NameAndType
   */
  public final void setNameAndTypeIndex(int name_and_type_index) {
    this.name_and_type_index = name_and_type_index;
  }

  /**
   * @return String representation.
   */
  public final String toString() {
    return super.toString() + "(class_index = " + class_index +
      ", name_and_type_index = " + name_and_type_index + ")";
  }    
}