ByteUtil.java

package ReadByteOneByOne;

public class ByteUtil {  
    /** 
     * 转换short为byte 
     *  
     * @param b 
     * @param s 
     *            需要转换的short 
     * @param index 
     */  
    public static void putShort(byte b[], short s, int index) {  
        b[index + 1] = (byte) (s >> 8);  
        b[index + 0] = (byte) (s >> 0);  
    }  
  
    /** 
     * 通过byte数组取到short 
     *  
     * @param b 
     * @param index 
     *            第几位开始取 
     * @return 
     */  
    public static short getShort(byte[] b, int index) {  
        return (short) (((b[index + 1] << 8) | b[index + 0] & 0xff));  
    }  
  
    /** 
     * 转换int为byte数组 
     *  
     * @param bb 
     * @param x 
     * @param index 
     */  
    public static void putInt(byte[] bb, int x, int index) {  
        bb[index + 3] = (byte) (x >> 24);  
        bb[index + 2] = (byte) (x >> 16);  
        bb[index + 1] = (byte) (x >> 8);  
        bb[index + 0] = (byte) (x >> 0);  
    }  
  
    /** 
     * 通过byte数组取到int 
     *  
     * @param bb 
     * @param index 
     *            第几位开始 
     * @return 
     */  
    public static int byte2int(byte[] b) {   
    	// 一个byte数据左移24位变成0x??000000，再右移8位变成0x00??0000   
    	  
    	return   b[3] & 0xFF |  
                (b[2] & 0xFF) << 8 |  
                (b[1] & 0xFF) << 16 |  
                (b[0] & 0xFF) << 24;    
    	} 
    /** 
     * 转换long型为byte数组 
     *  
     * @param bb 
     * @param x 
     * @param index 
     */  
    public static void putLong(byte[] bb, long x, int index) {  
        bb[index + 7] = (byte) (x >> 56);  
        bb[index + 6] = (byte) (x >> 48);  
        bb[index + 5] = (byte) (x >> 40);  
        bb[index + 4] = (byte) (x >> 32);  
        bb[index + 3] = (byte) (x >> 24);  
        bb[index + 2] = (byte) (x >> 16);  
        bb[index + 1] = (byte) (x >> 8);  
        bb[index + 0] = (byte) (x >> 0);  
    }  
  
    /** 
     * 通过byte数组取到long 
     *  
     * @param bb 
     * @param index 
     * @return 
     */  
    public static long getLong(byte[] bb, int index) {  
        return ((((long) bb[index + 7] & 0xff) << 56)  
                | (((long) bb[index + 6] & 0xff) << 48)  
                | (((long) bb[index + 5] & 0xff) << 40)  
                | (((long) bb[index + 4] & 0xff) << 32)  
                | (((long) bb[index + 3] & 0xff) << 24)  
                | (((long) bb[index + 2] & 0xff) << 16)  
                | (((long) bb[index + 1] & 0xff) << 8) | (((long) bb[index + 0] & 0xff) << 0));  
    }  
  
    /** 
     * 字符到字节转换 
     *  
     * @param ch 
     * @return 
     */  
    public static void putChar(byte[] bb, char ch, int index) {  
        int temp = (int) ch;  
        // byte[] b = new byte[2];   
        for (int i = 0; i < 2; i ++ ) {  
            bb[index + i] = new Integer(temp & 0xff).byteValue(); // 将最高位保存在最低位   
            temp = temp >> 8; // 向右移8位   
        }  
    }  
  
    /** 
     * 字节到字符转换 
     *  
     * @param b 
     * @return 
     */  
    public static char getChar(byte[] b, int index) {  
        int s = 0;  
        if (b[index + 1] > 0)  
            s += b[index + 1];  
        else  
            s += 256 + b[index + 0];  
        s *= 256;  
        if (b[index + 0] > 0)  
            s += b[index + 1];  
        else  
            s += 256 + b[index + 0];  
        char ch = (char) s;  
        return ch;  
    }  
  
    /** 
     * float转换byte 
     *  
     * @param bb 
     * @param x 
     * @param index 
     */  
    public static void putFloat(byte[] bb, float x, int index) {  
        // byte[] b = new byte[4];   
        int l = Float.floatToIntBits(x);  
        for (int i = 0; i < 4; i++) {  
            bb[index + i] = new Integer(l).byteValue();  
            l = l >> 8;  
        }  
    }  
  
    /** 
     * 通过byte数组取得float 
     *  
     * @param bb 
     * @param index 
     * @return 
     */  
    public static float getFloat(byte[] b, int index) {  
        int l;  
        l = b[index + 0];  
        l &= 0xff;  
        l |= ((long) b[index + 1] << 8);  
        l &= 0xffff;  
        l |= ((long) b[index + 2] << 16);  
        l &= 0xffffff;  
        l |= ((long) b[index + 3] << 24);  
        return Float.intBitsToFloat(l);  
    }  
  
    /** 
     * double转换byte 
     *  
     * @param bb 
     * @param x 
     * @param index 
     */  
    public static void putDouble(byte[] bb, double x, int index) {  
        // byte[] b = new byte[8];   
        long l = Double.doubleToLongBits(x);  
        for (int i = 0; i < 8; i++) {  
            bb[index + i] = new Long(l).byteValue();  
            l = l >> 8;  
        }  
    }  
  
    /** 
     * 通过byte数组取得double 
     *  
     * @param bb 
     * @param index 
     * @return 
     */  
    public static double getDouble(byte[] b, int index) {  
        long l;  
        l = b[0];  
        l &= 0xff;  
        l |= ((long) b[1] << 8);  
        l &= 0xffff;  
        l |= ((long) b[2] << 16);  
        l &= 0xffffff;  
        l |= ((long) b[3] << 24);  
        l &= 0xffffffffl;  
        l |= ((long) b[4] << 32);  
        l &= 0xffffffffffl;  
        l |= ((long) b[5] << 40);  
        l &= 0xffffffffffffl;  
        l |= ((long) b[6] << 48);  
        l &= 0xffffffffffffffl;  
        l |= ((long) b[7] << 56);  
        return Double.longBitsToDouble(l);  
    }  

    public static void putHexString(byte[] bb, String s, int index){
        for (int i = 0; i < s.length(); i+=2) {
            byte c= (byte)( charToByte(s.charAt(i))<<4 | charToByte(s.charAt(i+1)));
            bb[index+(i>>1)] = c;
        }
    }
    private static byte charToByte(char c) {   
        return (byte) "0123456789ABCDEF".indexOf(c);   
    } 
    
    public static String getHexString(byte[] b, int index, int count){   
        StringBuilder stringBuilder = new StringBuilder("");   
        if (b == null || index < 0 || b.length < index + count ) {   
            return null;   
        }   
        for (int i = index; i < count + index; i++) {   
            int v = b[i] & 0xFF;   
            String hv = Integer.toHexString(v);   
            if (hv.length() < 2) {   
                stringBuilder.append(0);   
            }   
            stringBuilder.append(hv);   
        }   
        return stringBuilder.toString();   
    }  
    
    public static String getBinaryString(int d,int length){
        StringBuilder stringBuilder = new StringBuilder(""); 
        String hv = Integer.toBinaryString(d);   
        for (int j = 0; j < length - hv.length(); j++) {
            stringBuilder.append(0);
        } 
        stringBuilder.append(hv); 
        return stringBuilder.toString();  
    }
    
    public static String getBinaryReverseString(int d,int length){
        StringBuilder stringBuilder = new StringBuilder(""); 
        String hv = Integer.toBinaryString(d);   
        for (int j = 0; j < length - hv.length(); j++) {
            stringBuilder.append(0);
        } 
        stringBuilder.append(hv); 
        stringBuilder.reverse();
        
        return stringBuilder.toString(); 
    }

    
    //网络字节逆序
    public static byte[] ReversEndian(byte b[],int count, boolean big)
    {
       byte by;
       byte data[] = new byte[count];
       for(int i=0;i<count;i++)
       {
           data[i] = b[i];           
       }
       if(big==false)
       {
           for(int i=0;i<count;i++)
           {
              by = b[i];
              data[count-i-1] = by;             
           }
       }      
       return data;
    }
    public static short htons(short s){
        short rslt = 0;
        byte [] bs1 = new byte[2];
        ByteUtil.putShort(bs1, s, 0);
        byte[] bs2 = ReversEndian(bs1, 2, false);
        rslt = ByteUtil.getShort(bs2, 0);
        return rslt;
    }
    public static int htonl(int d){
        int rslt = 0;
        byte [] bs1 = new byte[4];
        ByteUtil.putInt(bs1, d, 0);
        byte[] bs2 = ReversEndian(bs1, 4, false);
        rslt = ByteUtil.byte2int(bs2);
        return rslt;
    }
   
}