工作項目需要在java和c/c++之間進(jìn)行socket通信，socket通信是以字節流或者字節包進(jìn)行的，socket發(fā)送方須將數據轉換為字節流或者字節包，而接收方則將字節流和字節包再轉換回相應的數據類(lèi)型。如果發(fā)送方和接收方都是同種語(yǔ)言，則一般只涉及到字節序的調整。而對于java和c/c++的通信，則情況就要復雜一些，主要是因為java中沒(méi)有unsigned類(lèi)型，并且java和c在某些數據類(lèi)型上的長(cháng)度不一致。
本文就是針對這種情況，整理了java數據類(lèi)型和網(wǎng)絡(luò )字節流或字節包(相當于java的byte數組)之間轉換方法。實(shí)際上網(wǎng)上這方面的資料不少，但往往不全，甚至有些有錯誤，于是就花了點(diǎn)時(shí)間對java整型數和網(wǎng)絡(luò )字節序的byte[]之間轉換的各種情況做了一些驗證和整理。整理出來(lái)的函數如下：
public class ByteConvert {
// 以下 是整型數 和 網(wǎng)絡(luò )字節序的 byte[] 數組之間的轉換
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 類(lèi)型、 float、double 類(lèi)型和 byte[] 數組之間的轉換關(guān)系還需繼續研究實(shí)現。
}
測試程序如下：
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，下面的這行，并不能獲得正確的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();
}
}
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