invokeinterface.java

该开源工具主要用于class文件的操作

package org.apache.bcel.generic;

/* ====================================================================
 * 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
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 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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 * 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.classfile.ConstantPool;
import org.apache.bcel.Constants;
import org.apache.bcel.ExceptionConstants;

import java.io.*;
import org.apache.bcel.util.ByteSequence;

/** 
 * INVOKEINTERFACE - Invoke interface method
 * <PRE>Stack: ..., objectref, [arg1, [arg2 ...]] -&gt; ...</PRE>
 *
 * @version $Id: INVOKEINTERFACE.java,v 1.1.1.1 2001/10/29 20:00:16 jvanzyl Exp $
 * @author  <A HREF="mailto:[e-mail]">M. Dahm</A>
 */
public final class INVOKEINTERFACE extends InvokeInstruction {
  private int nargs; // Number of arguments on stack (number of stack slots), called "count" in vmspec2

  /**
   * Empty constructor needed for the Class.newInstance() statement in
   * Instruction.readInstruction(). Not to be used otherwise.
   */
  INVOKEINTERFACE() {}

  public INVOKEINTERFACE(int index, int nargs) {
    super(Constants.INVOKEINTERFACE, index);
    length = 5;

    if(nargs < 1)
      throw new ClassGenException("Number of arguments must be > 0 " + nargs);

    this.nargs = nargs;
  }

  /**
   * Dump instruction as byte code to stream out.
   * @param out Output stream
   */
  public void dump(DataOutputStream out) throws IOException {
    out.writeByte(opcode);
    out.writeShort(index);
    out.writeByte(nargs);
    out.writeByte(0);
  }

  /**
   * The <B>count</B> argument according to the Java Language Specification,
   * Second Edition.
   */
  public int getCount() { return nargs; }

  /**
   * Read needed data (i.e., index) from file.
   */
  protected void initFromFile(ByteSequence bytes, boolean wide)
       throws IOException
  {
    super.initFromFile(bytes, wide);

    length = 5;
    nargs = bytes.readUnsignedByte();
    bytes.readByte(); // Skip 0 byte
  }

  /**
   * @return mnemonic for instruction with symbolic references resolved
   */
  public String toString(ConstantPool cp) {
    return super.toString(cp) + " " + nargs;
  }

  public int consumeStack(ConstantPoolGen cpg) { // nargs is given in byte-code
    return nargs;  // nargs includes this reference
  }

  public Class[] getExceptions() {
    Class[] cs = new Class[4 + ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length];

    System.arraycopy(ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION, 0,
		     cs, 0, ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length);

    cs[ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length+3] = ExceptionConstants.INCOMPATIBLE_CLASS_CHANGE_ERROR;
    cs[ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length+2] = ExceptionConstants.ILLEGAL_ACCESS_ERROR;
    cs[ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length+1] = ExceptionConstants.ABSTRACT_METHOD_ERROR;
    cs[ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length]   = ExceptionConstants.UNSATISFIED_LINK_ERROR;

    return cs;
  }

  /**
   * Call corresponding visitor method(s). The order is:
   * Call visitor methods of implemented interfaces first, then
   * call methods according to the class hierarchy in descending order,
   * i.e., the most specific visitXXX() call comes last.
   *
   * @param v Visitor object
   */
  public void accept(Visitor v) {
    v.visitExceptionThrower(this);
    v.visitTypedInstruction(this);
    v.visitStackConsumer(this);
    v.visitStackProducer(this);
    v.visitLoadClass(this);
    v.visitCPInstruction(this);
    v.visitFieldOrMethod(this);
    v.visitInvokeInstruction(this);
    v.visitINVOKEINTERFACE(this);
  }
}