网路搜集：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(); } }