java byte数组与int，long，short，byte转换 

  1 public class DataTypeChangeHelper {
  2     /**
  3      * 将一个单字节的byte转换成32位的int
  4      * 
  5      * @param b
  6      *            byte
  7      * @return convert result
  8      */
  9     public static int unsignedByteToInt(byte b) {
 10         return (int) b & 0xFF;
 11     }
 12 
 13     /**
 14      * 将一个单字节的Byte转换成十六进制的数
 15      * 
 16      * @param b
 17      *            byte
 18      * @return convert result
 19      */
 20     public static String byteToHex(byte b) {
 21         int i = b & 0xFF;
 22         return Integer.toHexString(i);
 23     }
 24 
 25     /**
 26      * 将一个4byte的数组转换成32位的int
 27      * 
 28      * @param buf
 29      *            bytes buffer
 30      * @param byte[]中开始转换的位置
 31      * @return convert result
 32      */
 33     public static long unsigned4BytesToInt(byte[] buf, int pos) {
 34         int firstByte = 0;
 35         int secondByte = 0;
 36         int thirdByte = 0;
 37         int fourthByte = 0;
 38         int index = pos;
 39         firstByte = (0x000000FF & ((int) buf[index]));
 40         secondByte = (0x000000FF & ((int) buf[index + 1]));
 41         thirdByte = (0x000000FF & ((int) buf[index + 2]));
 42         fourthByte = (0x000000FF & ((int) buf[index + 3]));
 43         index = index + 4;
 44         return ((long) (firstByte << 24 | secondByte << 16 | thirdByte << 8 | fourthByte)) & 0xFFFFFFFFL;
 45     }
 46 
 47     /**
 48      * 将16位的short转换成byte数组
 49      * 
 50      * @param s
 51      *            short
 52      * @return byte[] 长度为2
 53      * */
 54     public static byte[] shortToByteArray(short s) {
 55         byte[] targets = new byte[2];
 56         for (int i = 0; i < 2; i++) {
 57             int offset = (targets.length - 1 - i) * 8;
 58             targets[i] = (byte) ((s >>> offset) & 0xff);
 59         }
 60         return targets;
 61     }
 62 
 63     /**
 64      * 将32位整数转换成长度为4的byte数组
 65      * 
 66      * @param s
 67      *            int
 68      * @return byte[]
 69      * */
 70     public static byte[] intToByteArray(int s) {
 71         byte[] targets = new byte[2];
 72         for (int i = 0; i < 4; i++) {
 73             int offset = (targets.length - 1 - i) * 8;
 74             targets[i] = (byte) ((s >>> offset) & 0xff);
 75         }
 76         return targets;
 77     }
 78 
 79     /**
 80      * long to byte[]
 81      * 
 82      * @param s
 83      *            long
 84      * @return byte[]
 85      * */
 86     public static byte[] longToByteArray(long s) {
 87         byte[] targets = new byte[2];
 88         for (int i = 0; i < 8; i++) {
 89             int offset = (targets.length - 1 - i) * 8;
 90             targets[i] = (byte) ((s >>> offset) & 0xff);
 91         }
 92         return targets;
 93     }
 94 
 95     /**32位int转byte[]*/
 96     public static byte[] int2byte(int res) {
 97         byte[] targets = new byte[4];
 98         targets[0] = (byte) (res & 0xff);// 最低位
 99         targets[1] = (byte) ((res >> 8) & 0xff);// 次低位
100         targets[2] = (byte) ((res >> 16) & 0xff);// 次高位
101         targets[3] = (byte) (res >>> 24);// 最高位,无符号右移。
102         return targets;
103     }
104 
105     /**
106      * 将长度为2的byte数组转换为16位int
107      * 
108      * @param res
109      *            byte[]
110      * @return int
111      * */
112     public static int byte2int(byte[] res) {
113         // res = InversionByte(res);
114         // 一个byte数据左移24位变成0x??000000，再右移8位变成0x00??0000
115         int targets = (res[0] & 0xff) | ((res[1] << 8) & 0xff00); // | 表示安位或
116         return targets;
117     }
118 }

 

posted @ 2015-08-26 13:59  dongweiq  阅读(517)  评论(0)    收藏  举报