java整型数与网络字节序的转换

java整型数与网络字节序的转换

/**
 * java整型数与网络字节序的 byte[] 数组转换关系
 * 工作项目需要在java和c/c++之间进行socket通信，socket通信是以字节流或者字节包进行的，socket发送方须将数据转换为字节流或者字节包，
 * 而接收方则将字节流和字节包再转换回相应的数据类型。如果发送方和接收方都是同种语言，则一般只涉及到字节序的调整。而对于java和c/c++的通信，
 * 则情况就要复杂一些，主要是因为java中没有unsigned类型，并且java和c在某些数据类型上的长度不一致。
 * 本文就是针对这种情况，整理了java数据类型和网络字节流或字节包(相当于java的byte数组)之间转换方法。实际上网上这方面的资料不少，但往往不全，
 * 甚至有些有错误，于是就花了点时间对java整型数和网络字节序的byte[]之间转换的各种情况做了一些验证和整理。
 * 
 * @author Administrator
 *
 */
public class ByteConvert {
	// 以下 是整型数 和 网络字节序的 byte[] 数组之间的转换
	public static byte[] longToBytes(long n) {
		byte[] b = new byte[8];
		b[7] = (byte) (n & 0xff);
		b[6] = (byte) (n >> 8 & 0xff);
		b[5] = (byte) (n >> 16 & 0xff);
		b[4] = (byte) (n >> 24 & 0xff);
		b[3] = (byte) (n >> 32 & 0xff);
		b[2] = (byte) (n >> 40 & 0xff);
		b[1] = (byte) (n >> 48 & 0xff);
		b[0] = (byte) (n >> 56 & 0xff);
		return b;
	}

    public static void longToBytes( long n, byte[] array, int offset ){
        array[7+offset] = (byte) (n & 0xff);
        array[6+offset] = (byte) (n >> 8 & 0xff);
        array[5+offset] = (byte) (n >> 16 & 0xff);
        array[4+offset] = (byte) (n >> 24 & 0xff);
        array[3+offset] = (byte) (n >> 32 & 0xff);
        array[2+offset] = (byte) (n >> 40 & 0xff);
        array[1+offset] = (byte) (n >> 48 & 0xff);
        array[0+offset] = (byte) (n >> 56 & 0xff);
    }
    
    public static long bytesToLong( byte[] array ){
        return ((((long) array[ 0] & 0xff) << 56)
              | (((long) array[ 1] & 0xff) << 48)
              | (((long) array[ 2] & 0xff) << 40)
              | (((long) array[ 3] & 0xff) << 32)
              | (((long) array[ 4] & 0xff) << 24)
              | (((long) array[ 5] & 0xff) << 16)
              | (((long) array[ 6] & 0xff) << 8) 
              | (((long) array[ 7] & 0xff) << 0));        
    }
    
    public static long bytesToLong( byte[] array, int offset ){
        return ((((long) array[offset + 0] & 0xff) << 56)
              | (((long) array[offset + 1] & 0xff) << 48)
              | (((long) array[offset + 2] & 0xff) << 40)
              | (((long) array[offset + 3] & 0xff) << 32)
              | (((long) array[offset + 4] & 0xff) << 24)
              | (((long) array[offset + 5] & 0xff) << 16)
              | (((long) array[offset + 6] & 0xff) << 8) 
              | (((long) array[offset + 7] & 0xff) << 0));            
    }
    
    public static byte[] intToBytes(int n) {
        byte[] b = new byte[4];
        b[3] = (byte) (n & 0xff);
        b[2] = (byte) (n >> 8 & 0xff);
        b[1] = (byte) (n >> 16 & 0xff);
        b[0] = (byte) (n >> 24 & 0xff);
        return b;
    }
    
    public static void intToBytes( int n, byte[] array, int offset ){
        array[3+offset] = (byte) (n & 0xff);
        array[2+offset] = (byte) (n >> 8 & 0xff);
        array[1+offset] = (byte) (n >> 16 & 0xff);
        array[offset] = (byte) (n >> 24 & 0xff);
    }    

    public static int bytesToInt(byte b[]) {
        return    b[3] & 0xff 
               | (b[2] & 0xff) << 8 
               | (b[1] & 0xff) << 16
               | (b[0] & 0xff) << 24;
    }

    public static int bytesToInt(byte b[], int offset) {
        return    b[offset+3] & 0xff 
               | (b[offset+2] & 0xff) << 8 
               | (b[offset+1] & 0xff) << 16
               | (b[offset] & 0xff) << 24;
    }

    public static byte[] uintToBytes( long n )
    {
        byte[] b = new byte[4];
        b[3] = (byte) (n & 0xff);
        b[2] = (byte) (n >> 8 & 0xff);
        b[1] = (byte) (n >> 16 & 0xff);
        b[0] = (byte) (n >> 24 & 0xff);
        
        return b;
    }

    public static void uintToBytes( long n, byte[] array, int offset ){
        array[3+offset] = (byte) (n );
        array[2+offset] = (byte) (n >> 8 & 0xff);
        array[1+offset] = (byte) (n >> 16 & 0xff);
        array[offset]   = (byte) (n >> 24 & 0xff);
    }

    public static long bytesToUint(byte[] array) {  
        return ((long) (array[3] & 0xff))  
             | ((long) (array[2] & 0xff)) << 8  
             | ((long) (array[1] & 0xff)) << 16  
             | ((long) (array[0] & 0xff)) << 24;  
    }

    public static long bytesToUint(byte[] array, int offset) {   
        return ((long) (array[offset+3] & 0xff))  
              | ((long) (array[offset+2] & 0xff)) << 8  
             | ((long) (array[offset+1] & 0xff)) << 16  
             | ((long) (array[offset]   & 0xff)) << 24;  
    }

    public static byte[] shortToBytes(short n) {
        byte[] b = new byte[2];
        b[1] = (byte) ( n       & 0xff);
        b[0] = (byte) ((n >> 8) & 0xff);
        return b;
    }
    
    public static void shortToBytes(short n, byte[] array, int offset ) {        
        array[offset+1] = (byte) ( n       & 0xff);
        array[offset] = (byte) ((n >> 8) & 0xff);
    }
    
    public static short bytesToShort(byte[] b){
        return (short)( b[1] & 0xff
                      |(b[0] & 0xff) << 8 ); 
    }    

    public static short bytesToShort(byte[] b, int offset){
        return (short)( b[offset+1] & 0xff
                      |(b[offset]    & 0xff) << 8 ); 
    }

    public static byte[] ushortToBytes(int n) {
        byte[] b = new byte[2];
        b[1] = (byte) ( n       & 0xff);
        b[0] = (byte) ((n >> 8) & 0xff);
        return b;
    }    

    public static void ushortToBytes(int n, byte[] array, int offset ) {
        array[offset+1] = (byte) ( n       & 0xff);
        array[offset] = (byte)   ((n >> 8) & 0xff);
    }

    public static int bytesToUshort(byte b[]) {
        return    b[1] & 0xff 
               | (b[0] & 0xff) << 8;
    }    

    public static int bytesToUshort(byte b[], int offset) {
        return    b[offset+1] & 0xff 
               | (b[offset]   & 0xff) << 8;
    }    

    public static byte[] ubyteToBytes( int n ){
        byte[] b = new byte[1];
        b[0] = (byte) (n & 0xff);
        return b;
    }

    public static void ubyteToBytes( int n, byte[] array, int offset ){
        array[0] = (byte) (n & 0xff);
    }

    public static int bytesToUbyte( byte[] array ){            
        return array[0] & 0xff;
    }        

    public static int bytesToUbyte( byte[] array, int offset ){            
        return array[offset] & 0xff;
    }    
    // char 类型、 float、double 类型和 byte[] 数组之间的转换关系还需继续研究实现。 
}