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。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。 }测试程序如下：public class ByteConvertTest {        public static String byte2Hex(byte[] buf)     {        StringBuffer strbuf = new StringBuffer();        strbuf.append("{");        for (byte b : buf)         {            if (b == 0)             {                strbuf.append("00");            }             else if (b == -1)             {                strbuf.append("FF");            }             else             {                String str = Integer.toHexString(b).toUpperCase();                // sb.append(a);                if (str.length() == 8)                 {                    str = str.substring(6, 8);                }                 else if (str.length() < 2)                 {                    str = "0" + str;                }                strbuf.append(str);            }            strbuf.append(" ");        }        strbuf.append("}");        return strbuf.toString();    }        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 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) ));            }        public static int bytesToInt(byte b[]) {        return    b[3] & 0xff                | (b[2] & 0xff) << 8                | (b[1] & 0xff) << 16               | (b[0] & 0xff) << 24;    }    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 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 byte[] shortToBytes(short n) {        byte[] b = new byte[2];        b[1] = (byte) ( n       & 0xff);        b[0] = (byte) ((n >> 8) & 0xff);        return b;    }        public static short bytesToShort(byte[] b){        return (short)( b[1] & 0xff                      |(b[0] & 0xff) << 8 );     }        static void testShortConvert(){        System.out.println("=================== short convert =============");        System.out.println("byte2Hex(shortToBytes((short)0x11f2))"+byte2Hex(shortToBytes((short)0x11f2)));                System.out.print("println 0x11f2:");        System.out.println((short)0x11f2);                System.out.println("byte2Hex(shortToBytes((short)0xf1f2))"+byte2Hex(shortToBytes((short)0xf1f2)));                System.out.print("println 0xf1f2:");        System.out.println((short)0xf1f2);                    System.out.print("println bytesToShort(shortToBytes((short)0x11f2)):");        System.out.println((short)bytesToShort(shortToBytes((short)0x11f2)));                    System.out.print("println bytesToShort(shortToBytes((short)0xf1f2)):");        System.out.println((short)bytesToShort(shortToBytes((short)0xf1f2)));            }        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 int bytesToUshort(byte b[]) {        return    b[1] & 0xff                | (b[0] & 0xff) << 8;    }    static void testUshortConvert(){        System.out.println("=================== Ushort convert =============");        System.out.println("byte2Hex(ushortToBytes(0x11f2))"+byte2Hex(ushortToBytes(0x11f2)));                System.out.print("println 0x11f2:");        System.out.println(0x11f2);                System.out.println("byte2Hex(ushortToBytes(0xf1f2))"+byte2Hex(ushortToBytes(0xf1f2)));                System.out.print("println 0xf1f2:");        System.out.println(0xf1f2);                    System.out.print("println bytesToUshort(ushortToBytes(0x11f2)):");        System.out.println(bytesToUshort(ushortToBytes(0x11f2)));                    System.out.print("println bytesToUshort(ushortToBytes(0xf1f2)):");        System.out.println(bytesToUshort(ushortToBytes(0xf1f2)));            }        public static byte[] ubyteToBytes( int n ){        byte[] b = new byte[1];        b[0] = (byte) (n & 0xff);        return b;    }    public static int bytesToUbyte( byte[] array ){                    return array[0] & 0xff;    }        static void testUbyteConvert(){        System.out.println("=================== Ubyte convert =============");        System.out.println("byte2Hex(ubyteToBytes(0x1112))"+byte2Hex(ubyteToBytes(0x1112)));                System.out.print("println 0x1112:");        System.out.println(0x1112);                System.out.println("byte2Hex(ubyteToBytes(0xf2))"+byte2Hex(ubyteToBytes(0xf2)));                System.out.print("println 0xf2:");        System.out.println(0xf2);                    System.out.print("println bytesToUbyte(ubyteToBytes(0x1112)):");        System.out.println(bytesToUbyte(ubyteToBytes(0x1112)));                    System.out.print("println bytesToUbyte(ubyteToBytes(0xf1f2)):");        System.out.println(bytesToUbyte(ubyteToBytes(0xf1f2)));            }            /**     * @param args     */    public static void main(String[] args) {        // TODO Auto-generated method stub                byte[] array = new byte[4];        array[3] = (byte) 0xF4;        array[2] = 0x13;        array[1] = 0x12;        array[0] = 0x11;                System.out.println("=================== Integer bytes =============");                System.out.println("the bytes is:"+byte2Hex(array) );        System.out.print("println bytesToInt :");        System.out.println( bytesToInt(array));        System.out.printf("printf bytesToInt :%X\n", bytesToInt(array));                System.out.println("=================== long bytes =============");        byte[] longBytes = new byte[8];                longBytes[7] = (byte) 0xf7;        longBytes[6] = (byte) 0x16;        longBytes[5] = (byte) 0xf5;        longBytes[4] = (byte) 0x14;        longBytes[3] = (byte) 0xf3;        longBytes[2] = (byte) 0x12;        longBytes[1] = (byte) 0xf1;        longBytes[0] = (byte) 0x10;                System.out.println( "the bytes is:"+byte2Hex(longBytes) );        System.out.printf("printf bytesToLong:%X\n",bytesToLong(longBytes));                System.out.println("=================byte to long ================");                byte b = (byte)0xf1;        System.out.print("Println the byte:");        System.out.println(b);        System.out.printf("Printf the byte:%X\n",b);        long l = b;        System.out.print("Println byte to long:");        System.out.println(l);        System.out.printf("printf byte to long:%X\n",l);                System.out.println("================= uint Bytes ================");                byte[] uint = new byte[4];        uint[3] = (byte) 0xf3;        uint[2] = (byte) 0x12;        uint[1] = (byte) 0xf1;        uint[0] = (byte) 0xFF;                System.out.println( "the bytes is:"+byte2Hex(uint) );        System.out.printf("printf bytesToUint:%X\n",bytesToUint(uint));        System.out.print("Println bytesToUint:");        System.out.println(bytesToUint(uint));        System.out.println("byte2Hex(uintToBytes(0x11f2f3f4f5f6f7f8l)):"+byte2Hex(uintToBytes(0x11f2f3f4f5f6f7f8l)));                System.out.println("===============Long Integer==============");                System.out.print("println 0x11f2f3f4f5f6f7f8l:");        System.out.println(0x11f2f3f4f5f6f7f8l);                System.out.printf("Printf 0x11f2f3f4f5f6f7f8l:%X\n",0x11f2f3f4f5f6f7f8l);        System.out.println("println byte2Hex(longToBytes(0x11f2f3f4f5f6f7f8l))"+byte2Hex(longToBytes(0x11f2f3f4f5f6f7f8l)));        // 注意，下面的这行，并不能获得正确的uint。        System.out.printf("printf bytesToUint(longToBytes(0x11f2f3f4f5f6f7f8l):%X\n",bytesToUint(longToBytes(0x11f2f3f4f5f6f7f8l)));                System.out.println("===============bytesToLong(longToBytes())==============");        System.out.println(bytesToLong(longToBytes(0x11f2f3f4f5f6f7f8l)));        System.out.printf("%X\n",bytesToLong(longToBytes(0x11f2f3f4f5f6f7f8l)));                testShortConvert();        testUshortConvert();        testUbyteConvert();    }}