bytereader.java

来自「一个基于J2ME技术的程序,使你可以远程控制装有服务端的PC.」· Java 代码 · 共 79 行

/*
 * JRemCntl - Copyright (C) 2007 Filippo Di Vattimo <[e-mail]>
 * See COPYING
 */

package fildiv.jremcntl.common.proto;

import java.io.UnsupportedEncodingException;

import fildiv.jremcntl.common.core.JRemRuntimeException;

public class ByteReader {

	private byte[] bytes;
	private int offset;

	public ByteReader() {
	}
		
	public ByteReader(byte[] bytes) {
		setBytes(bytes);
	}
	
	public void setBytes(byte[] bytes) {
		if (bytes == null)
			throw new IllegalArgumentException();

		this.bytes = bytes;
		offset = 0;
	}
	
	public byte[] getBytes() {
		return bytes;
	}
	
	protected void safeOffsetAdd(int offset) {
		
		this.offset += offset;
		
		if(this.offset > bytes.length)
			throw new IndexOutOfBoundsException();
	}
	
	public String getString() {
		int size = getInt();
		
		String str = "";
		
		try {
			str = new String(bytes, offset, size, "UTF-8");
		} catch (UnsupportedEncodingException e) {
			throw new JRemRuntimeException(e);
		}
		safeOffsetAdd(size);
		
		return str;
	}

	public int getInt() {
		int value = (((bytes[offset] & 0xff) << 24)
               | ((bytes[offset + 1] & 0xff) << 16)
               | ((bytes[offset + 2] & 0xff) << 8) 
               | (bytes[offset + 3] & 0xff));		
		
		safeOffsetAdd(JRemAbstractProtocol.LENGHT_INT);
		
		return value;
	}

	public short getShort() {
		short value = (short) (((bytes[offset + 0] & 0xff) << 8) 
	           | (bytes[offset + 1] & 0xff));		
		
		safeOffsetAdd(JRemAbstractProtocol.LENGHT_SHORT);
		
		return value;
	}
}