java byte数组与int，long，short，byte转换

public class DataTypeChangeHelper {
/**
* 将一个单字节的byte转换成32位的int
*
* @param b
* byte
* @return convert result
*/
public static int unsignedByteToInt(byte b) {
return (int) b & 0xFF;
}

/**
 * 将一个单字节的Byte转换成十六进制的数
 * 
 * @param b
 *            byte
 * @return convert result
 */
public static String byteToHex(byte b) {
    int i = b & 0xFF;
    return Integer.toHexString(i);
}

/**
 * 将一个4byte的数组转换成32位的int
 * 
 * @param buf
 *            bytes buffer
 * @param byte[]中开始转换的位置
 * @return convert result
 */
public static long unsigned4BytesToInt(byte[] buf, int pos) {
    int firstByte = 0;
    int secondByte = 0;
    int thirdByte = 0;
    int fourthByte = 0;
    int index = pos;
    firstByte = (0x000000FF & ((int) buf[index]));
    secondByte = (0x000000FF & ((int) buf[index + 1]));
    thirdByte = (0x000000FF & ((int) buf[index + 2]));
    fourthByte = (0x000000FF & ((int) buf[index + 3]));
    index = index + 4;
    return ((long) (firstByte << 24 | secondByte << 16 | thirdByte << 8 | fourthByte)) & 0xFFFFFFFFL;
}

/**
 * 将16位的short转换成byte数组
 * 
 * @param s
 *            short
 * @return byte[] 长度为2
 * */
public static byte[] shortToByteArray(short s) {
    byte[] targets = new byte[2];
    for (int i = 0; i < 2; i++) {
        int offset = (targets.length - 1 - i) * 8;
        targets[i] = (byte) ((s >>> offset) & 0xff);
    }
    return targets;
}

/**
 * 将32位整数转换成长度为4的byte数组
 * 
 * @param s
 *            int
 * @return byte[]
 * */
public static byte[] intToByteArray(int s) {
    byte[] targets = new byte[2];
    for (int i = 0; i < 4; i++) {
        int offset = (targets.length - 1 - i) * 8;
        targets[i] = (byte) ((s >>> offset) & 0xff);
    }
    return targets;
}

/**
 * long to byte[]
 * 
 * @param s
 *            long
 * @return byte[]
 * */
public static byte[] longToByteArray(long s) {
    byte[] targets = new byte[2];
    for (int i = 0; i < 8; i++) {
        int offset = (targets.length - 1 - i) * 8;
        targets[i] = (byte) ((s >>> offset) & 0xff);
    }
    return targets;
}

/**32位int转byte[]*/
public static byte[] int2byte(int res) {
    byte[] targets = new byte[4];
    targets[0] = (byte) (res & 0xff);// 最低位
    targets[1] = (byte) ((res >> 8) & 0xff);// 次低位
    targets[2] = (byte) ((res >> 16) & 0xff);// 次高位
    targets[3] = (byte) (res >>> 24);// 最高位,无符号右移。
    return targets;
}

/**
 * 将长度为2的byte数组转换为16位int
 * 
 * @param res
 *            byte[]
 * @return int
 * */
public static int byte2int(byte[] res) {
    // res = InversionByte(res);
    // 一个byte数据左移24位变成0x??000000，再右移8位变成0x00??0000
    int targets = (res[0] & 0xff) | ((res[1] << 8) & 0xff00); // | 表示安位或
    return targets;
}

}