Java的类库支持完全不如C#，比如时间类，比如数据类型转换类等等，难道是我自己没找到吗？
下面是字节转换类，byte[]与short, int, long, float, double, String相互转换；网络字节序htons, htonl等实现；byte[]转十六进制字符串、二进制字符串实现。
希望对朋友有用，如果有更好的方法，请提醒我。
public class ByteUtil {
/**
* 转换short为byte
*
* @param b
* @param s
* 需要转换的short
* @param index
*/
public static void putShort(byte b[], short s, int index) {
b[index + 1] = (byte) (s >> 8);
b[index + 0] = (byte) (s >> 0);
}
/**
* 通过byte数组取到short
*
* @param b
* @param index
* 第几位开始取
* @return
*/
public static short getShort(byte[] b, int index) {
return (short) (((b[index + 1] << 8) | b[index + 0] & 0xff));
}
/**
* 转换int为byte数组
*
* @param bb
* @param x
* @param index
*/
public static void putInt(byte[] bb, int x, int index) {
bb[index + 3] = (byte) (x >> 24);
bb[index + 2] = (byte) (x >> 16);
bb[index + 1] = (byte) (x >> 8);
bb[index + 0] = (byte) (x >> 0);
}
/**
* 通过byte数组取到int
*
* @param bb
* @param index
* 第几位开始
* @return
*/
public static int getInt(byte[] bb, int index) {
return (int) ((((bb[index + 3] & 0xff) << 24)
| ((bb[index + 2] & 0xff) << 16)
| ((bb[index + 1] & 0xff) << 8) | ((bb[index + 0] & 0xff) << 0)));
}
/**
* 转换long型为byte数组
*
* @param bb
* @param x
* @param index
*/
public static void putLong(byte[] bb, long x, int index) {
bb[index + 7] = (byte) (x >> 56);
bb[index + 6] = (byte) (x >> 48);
bb[index + 5] = (byte) (x >> 40);
bb[index + 4] = (byte) (x >> 32);
bb[index + 3] = (byte) (x >> 24);
bb[index + 2] = (byte) (x >> 16);
bb[index + 1] = (byte) (x >> 8);
bb[index + 0] = (byte) (x >> 0);
}
/**
* 通过byte数组取到long
*
* @param bb
* @param index
* @return
*/
public static long getLong(byte[] bb, int index) {
return ((((long) bb[index + 7] & 0xff) << 56)
| (((long) bb[index + 6] & 0xff) << 48)
| (((long) bb[index + 5] & 0xff) << 40)
| (((long) bb[index + 4] & 0xff) << 32)
| (((long) bb[index + 3] & 0xff) << 24)
| (((long) bb[index + 2] & 0xff) << 16)
| (((long) bb[index + 1] & 0xff) << 8) | (((long) bb[index + 0] & 0xff) << 0));
}
/**
* 字符到字节转换
*
* @param ch
* @return
*/
public static void putChar(byte[] bb, char ch, int index) {
int temp = (int) ch;
// byte[] b = new byte[2];
for (int i = 0; i < 2; i ++ ) {
bb[index + i] = new Integer(temp & 0xff).byteValue(); // 将最高位保存在最低位
temp = temp >> 8; // 向右移8位
}
}
/**
* 字节到字符转换
*
* @param b
* @return
*/
public static char getChar(byte[] b, int index) {
int s = 0;
if (b[index + 1] > 0)
s += b[index + 1];
else
s += 256 + b[index + 0];
s *= 256;
if (b[index + 0] > 0)
s += b[index + 1];
else
s += 256 + b[index + 0];
char ch = (char) s;
return ch;
}
/**
* float转换byte
*
* @param bb
* @param x
* @param index
*/
public static void putFloat(byte[] bb, float x, int index) {
// byte[] b = new byte[4];
int l = Float.floatToIntBits(x);
for (int i = 0; i < 4; i++) {
bb[index + i] = new Integer(l).byteValue();
l = l >> 8;
}
}
/**
* 通过byte数组取得float
*
* @param bb
* @param index
* @return
*/
public static float getFloat(byte[] b, int index) {
int l;
l = b[index + 0];
l &= 0xff;
l |= ((long) b[index + 1] << 8);
l &= 0xffff;
l |= ((long) b[index + 2] << 16);
l &= 0xffffff;
l |= ((long) b[index + 3] << 24);
return Float.intBitsToFloat(l);
}
/**
* double转换byte
*
* @param bb
* @param x
* @param index
*/
public static void putDouble(byte[] bb, double x, int index) {
// byte[] b = new byte[8];
long l = Double.doubleToLongBits(x);
for (int i = 0; i < 8; i++) {
bb[index + i] = new Long(l).byteValue();
l = l >> 8;
}
}
/**
* 通过byte数组取得double
*
* @param bb
* @param index
* @return
*/
public static double getDouble(byte[] b, int index) {
long l;
l = b[0];
l &= 0xff;
l |= ((long) b[1] << 8);
l &= 0xffff;
l |= ((long) b[2] << 16);
l &= 0xffffff;
l |= ((long) b[3] << 24);
l &= 0xffffffffl;
l |= ((long) b[4] << 32);
l &= 0xffffffffffl;
l |= ((long) b[5] << 40);
l &= 0xffffffffffffl;
l |= ((long) b[6] << 48);
l &= 0xffffffffffffffl;
l |= ((long) b[7] << 56);
return Double.longBitsToDouble(l);
}
public static void putHexString(byte[] bb, String s, int index){
for (int i = 0; i < s.length(); i+=2) {
byte c= (byte)( charToByte(s.charAt(i))<<4 | charToByte(s.charAt(i+1)));
bb[index+(i>>1)] = c;
}
}
private static byte charToByte(char c) {
return (byte) "0123456789ABCDEF".indexOf(c);
}
public static String getHexString(byte[] b, int index, int count){
StringBuilder stringBuilder = new StringBuilder("");
if (b == null || index < 0 || b.length < index + count ) {
return null;
}
for (int i = index; i < count + index; i++) {
int v = b[i] & 0xFF;
String hv = Integer.toHexString(v);
if (hv.length() < 2) {
stringBuilder.append(0);
}
stringBuilder.append(hv);
}
return stringBuilder.toString();
}
public static String getBinaryString(int d,int length){
StringBuilder stringBuilder = new StringBuilder("");
String hv = Integer.toBinaryString(d);
for (int j = 0; j < length - hv.length(); j++) {
stringBuilder.append(0);
}
stringBuilder.append(hv);
return stringBuilder.toString();
}
public static String getBinaryReverseString(int d,int length){
StringBuilder stringBuilder = new StringBuilder("");
String hv = Integer.toBinaryString(d);
for (int j = 0; j < length - hv.length(); j++) {
stringBuilder.append(0);
}
stringBuilder.append(hv);
stringBuilder.reverse();
return stringBuilder.toString();
}
//网络字节逆序
public static byte[] ReversEndian(byte b[],int count, boolean big)
{
byte by;
byte data[] = new byte[count];
for(int i=0;i<count;i++)
{
data[i] = b[i];
}
if(big==false)
{
for(int i=0;i<count;i++)
{
by = b[i];
data[count-i-1] = by;
}
}
return data;
}
public static short htons(short s){
short rslt = 0;
byte [] bs1 = new byte[2];
ByteUtil.putShort(bs1, s, 0);
byte[] bs2 = ReversEndian(bs1, 2, false);
rslt = ByteUtil.getShort(bs2, 0);
return rslt;
}
public static int htonl(int d){
int rslt = 0;
byte [] bs1 = new byte[4];
ByteUtil.putInt(bs1, d, 0);
byte[] bs2 = ReversEndian(bs1, 4, false);
rslt = ByteUtil.getInt(bs2, 0);
return rslt;
}
}