java整型数与网络字节序的 byte[] 数组转换关系

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 longT oBytes( 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) {