lookupswitch.java

Java Bytecode Editor 是一个 JAVA 的字节码反汇编和修改器。它可以很方便的修改已经编译成 Class 文件的 JAVA 文件。

package org.apache.bcel.generic;

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 * This software consists of voluntary contributions made by many
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 */
import java.io.*;
import org.apache.bcel.util.ByteSequence;

/**
 * LOOKUPSWITCH - Switch with unordered set of values
 * 
 * @version $Id: LOOKUPSWITCH.java,v 1.4 2006/08/23 13:48:30 andos Exp $
 * @author <A HREF="mailto:[e-mail]">M. Dahm</A>. Modified by Ando
 *         Saabas
 * @see SWITCH
 */
public class LOOKUPSWITCH extends Select {
	/**
	 * 
	 */
	private static final long serialVersionUID = -5182745845131218825L;

	/**
	 * Empty constructor needed for the Class.newInstance() statement in
	 * Instruction.readInstruction(). Not to be used otherwise.
	 */
	public LOOKUPSWITCH() {
		super(org.apache.bcel.Constants.LOOKUPSWITCH);
	}

	public LOOKUPSWITCH(int[] match, InstructionHandle[] targets,
			InstructionHandle target) {
		super(org.apache.bcel.Constants.LOOKUPSWITCH, match, targets, target);

		length = (short) (9 + match_length * 8); /*
													 * alignment remainder
													 * assumed 0 here, until
													 * dump time.
													 */
		fixed_length = length;
	}

	/**
	 * Dump instruction as byte code to stream out.
	 * 
	 * @param out
	 *            Output stream
	 */
	public void dump(DataOutputStream out) throws IOException {
		super.dump(out);
		out.writeInt(match_length); // npairs

		for (int i = 0; i < match_length; i++) {
			out.writeInt(match[i]); // match-offset pairs
			out.writeInt(indices[i] = getTargetOffset(targets[i]));
		}
	}

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

		match_length = bytes.readInt();
		fixed_length = (short) (9 + match_length * 8);
		length = (short) (fixed_length + padding);

		match = new int[match_length];
		indices = new int[match_length];
		targets = new InstructionHandle[match_length];

		for (int i = 0; i < match_length; i++) {
			match[i] = bytes.readInt();
			indices[i] = bytes.readInt();
		}
	}

	/**
	 * 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.visitVariableLengthInstruction(this);
		v.visitStackProducer(this);
		v.visitBranchInstruction(this);
		v.visitSelect(this);
		v.visitLOOKUPSWITCH(this);
	}

	public void setMatchesTargets(int[] match, InstructionHandle[] targets) {
		super.setMatchesTargets(match, targets);
		length = (short) (9 + match_length * 8); /*
													 * alignment remainder
													 * assumed 0 here, until
													 * dump time.
													 */
		fixed_length = length;
	}

}