利用Java在将整型数与byte[]数组进行转换

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具体如下：

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。

针对这种情况，本文整理了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。整理出来的函数如下：

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。}