如何读字节从输入流取bit作位运算(JAVA实现)

在以下是笔者在遇到取bit位运算，源码如下：

package com.bit;

import java.io.ByteArrayInputStream;

import java.io.DataInputStream;

import java.io.IOException;

public class BitTest {

byte[] content = {(byte)9,(byte)111,(byte)120,(byte)32};

public  String readBitYear(byte[] bt) throws IOException {

byte[] tmp = bt;

byte a = new DataInputStream(new    ByteArrayInputStream(tmp)).readByte();;

//int aa =  (a & 0xfc);

int aa = a >>2<<2;

aa += 2000;

String year = Integer.toString(aa);

return year;

}

public  String readBitMoth(byte[] bt) throws IOException {

byte[] tmp = bt;

int b = (int)new DataInputStream(new   ByteArrayInputStream(tmp)).readShort();

int bb =  b & 0x03C0;

bb = bb >> 6;

String mon = Integer.toString(bb);

while (mon.length()<2) {

mon = "0"+mon;

}

return mon;

}

public  String readBitDay(byte[] bt) throws IOException {

byte[] tmp = bt;

int c = (int)new DataInputStream(new ByteArrayInputStream(tmp)).readShort();

int cc =  c & 0x003E;

cc = cc >> 1;

String day = Integer.toString(cc);

while (day.length()<2) {

day = "0"+day;

}

return day;

}

public  String readBithour(byte[] bt) throws IOException {

byte[] tmp = bt;

DataInputStream tmp_dis = new DataInputStream(new ByteArrayInputStream(tmp));

tmp_dis.readByte();

int d1 = tmp_dis.readShort();

int dd =  d1 & 0x1f0;

dd = dd >> 4;

String hour = Integer.toString(dd);

while (hour.length()<2) {

hour = "0"+hour;

}

return hour;

}

public  String readBitmin(byte[] bt) throws IOException {

byte[] tmp = bt;

DataInputStream tmp_dis = new DataInputStream(new ByteArrayInputStream(tmp));

tmp_dis.readShort();

int e = tmp_dis.readShort();

int ee =  e & 0xfc0;

ee = ee >> 6;

String min = Integer.toString(ee);

while (min.length()<2) {

min = "0"+min;

}

return min;

}

public  String readBitsec(byte[] bt) throws IOException {

byte[] tmp = bt;

DataInputStream tmp_dis = new DataInputStream(new ByteArrayInputStream(tmp));

tmp_dis.readShort();

int f = tmp_dis.readShort();

int ff =  f & 0x3f;

String sec = Integer.toString(ff);

while (sec.length()<2) {

sec = "0"+sec;

}

return sec;

}

/**

* @param args

* @throws IOException

*/

public static void main(String[] args) throws IOException {

// TODO Auto-generated method stub

BitTest bittest = new BitTest();

String year = bittest.readBitYear(bittest.content);

String month = bittest.readBitMoth(bittest.content);

String day = bittest.readBitDay(bittest.content);

String hour = bittest.readBithour(bittest.content);

String min = bittest.readBitmin(bittest.content);

String sec = bittest.readBitsec(bittest.content);

System.out.println("year's :" + year);

System.out.println("month's :" + month);

System.out.println("day's :" + day);

System.out.println("hour's :" + hour);

System.out.println("min's :" + min);

System.out.println("sec's :" + sec);

}