java整型数与网络字节序的 byte[] 数组转换关系【转】

原文：http://fire11.iteye.com/blog/1029925

因工作需要在java和c/c++之间进行socket通信，而socket通信是以字节流或者字节包进行的(这相当于java的byte[]数组)，所以需要在java数据类型和网络字节流(包)之间进行转换。网上这方面的资料不少，但往往不全，甚至有些有错漏。于是自己花时间对java整型数和网络字节序的byte[]之间的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();
}

}