bitreader.java

来自「如 题」· Java 代码 · 共 62 行

package kava.util;

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.IOException;

public class BitReader {
	
	private BufferedInputStream bis;
	private int readCount;
	private byte cacheByte;
	public BitReader(BufferedInputStream bis){
		this.bis = bis;
		readCount = 8;
	}
	/**
	 * 
	 * @return 0 or 1,-1 means EOF
	 */
	public byte readBit(){
		if(readCount == 8){
			int value = -1;
			try {
				value = bis.read();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			if(value == -1){
				return -1;
			}
			cacheByte = (byte)value; 
			readCount = 0;
		}
		int mask =  0x80 >>> readCount;
		readCount ++;
		return (byte)((cacheByte & mask) >>> ( 8 - readCount));
		
	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		  BitWriter bw = new BitWriter(128);
		  bw.write(1, 1);
		  bw.write(1, 1);
		  bw.write(1, 1);
		  byte[] data = bw.toByteArray();
		  Util.debug("len = "+data.length +"  "+Util.byteArrayToHexString(data));
		  ByteArrayInputStream bais = new ByteArrayInputStream(data);
		  BitReader br = new BitReader(new BufferedInputStream(bais));
		  byte b;
		  while((b = br.readBit()) != -1){
			  Util.debug(""+b);
		  }
		 
	}

}