java大小端转换工具类
最近的项目频繁涉及大小端转换的情况，参考github（https://github.com/Frank-Wiebeler/java-Big2LittleEndian/blob/master/src/com/dev4ag/Big2LittleEndian.java）自己改了一个大小端转换的工具类，记录一下；
package com.ruijie.iotp.common.webcomponent.util;
/**
* Description 大小端转换工具类
* */
public class EndianUtil {
public static byte[] short2LittleEndianBytes(short val){
return short2Bytes(short2LittleEndian(val));
}
public static byte[] int2LittleEndianBytes(int val){
return int2Bytes(int2LittleEndian(val));
}
public static byte[] long2LittleEndianBytes(long val){
return long2Bytes(long2LittleEndian(val));
}
/**
* Reformats a Little Endian value to bigEndian
* @param val the value to transform
* @return Big Endian Value
*/
public static short short2LittleEndian(short val){
return (short)(((val&0xff00)>>>8) + ((val&0x00ff)<<8));
}
/**
* Reformats a Little Endian value to bigEndian
* @param val the value to transform
* @return Big Endian Value
*/
public static int int2LittleEndian(int val){
return
( ( val&0xff000000 ) >>> 24 ) +
( (( val&0x00ff0000 ) >>> 16 ) << 8 ) +
( (( val&0x0000ff00 ) >>> 8 ) << 16 ) +
( (( val&0x000000ff ) ) << 24 )
;
}
/**
* Reformats a Little Endian value to bigEndian
* @param val the value to transform
* @return Big Endian Value
*/
public static long long2LittleEndian(long val){
return
( (val&0xff00000000000000L) >>> 56 ) +
(((val&0x00ff000000000000L) >>> 48 ) << 8 ) +
(((val&0x0000ff0000000000L) >>> 40 ) << 16 ) +
(((val&0x000000ff00000000L) >>> 32 ) << 24 ) +
(((val&0x00000000ff000000L) >>> 24 ) << 32 ) +
(((val&0x0000000000ff0000L) >>> 16 ) << 40 ) +
(((val&0x000000000000ff00L) >>> 8 ) << 48 ) +
(((val&0x00000000000000ffL) ) << 56 )
;
}
/**
* ================================================================================
* The other way arround
* Fun fact: If you turn the bytes, the bytes turn. If you do it twice, you undo it.
* Turn AB to BA and turn it again => AB. Magic :)
* So, it's all basically the same functions.
*
* However, we create some alias functions to make it
* readable in your source code, what you assume to do :)
*/
/**
* Reformats a Little Endian value to bigEndian
* @param val the value to transform
* @return Big Endian Value
*/
public static int intFromLittleEndian(int val){
return int2LittleEndian(val);
}
public static short shortFromLittleEndian(short val){
return short2LittleEndian(val);
}
public static long longFromLittleEndian(long val){
return long2LittleEndian(val);
}
public static byte[] long2Bytes(long a) {
return new byte[] {
(byte) ((a >> 56) & 0xFF),
(byte) ((a >> 48) & 0xFF),
(byte) ((a >> 40) & 0xFF),
(byte) ((a >> 32) & 0xFF),
(byte) ((a >> 24) & 0xFF),
(byte) ((a >> 16) & 0xFF),
(byte) ((a >> 8) & 0xFF),
(byte) (a & 0xFF)
};
}
public static byte[] int2Bytes(int a) {
return new byte[] {
(byte) ((a >> 24) & 0xFF),
(byte) ((a >> 16) & 0xFF),
(byte) ((a >> 8) & 0xFF),
(byte) (a & 0xFF)
};
}
public static byte[] short2Bytes(short a) {
return new byte[] {
(byte) ((a >> 8) & 0xFF),
(byte) (a & 0xFF)
};
}
public static long bytes2Long(byte[]bytes) {
return (0xffL & (long)bytes[7])
| (0xff00L & ((long)bytes[6] << 8))
| (0xff0000L & ((long)bytes[5] << 16))
| (0xff000000L & ((long)bytes[4] << 24))
| (0xff00000000L & ((long)bytes[3] << 32))
| (0xff0000000000L & ((long)bytes[2] << 40))
| (0xff000000000000L & ((long)bytes[1] << 48))
| (0xff00000000000000L & ((long)bytes[0] << 56));
}
public static long bytes2LongBigEndian(byte[]bytes) {
return (0xffL & (long)bytes[0])
| (0xff00L & ((long)bytes[1] << 8))
| (0xff0000L & ((long)bytes[2] << 16))
| (0xff000000L & ((long)bytes[3] << 24))
| (0xff00000000L & ((long)bytes[4] << 32))
| (0xff0000000000L & ((long)bytes[5] << 40))
| (0xff000000000000L & ((long)bytes[6] << 48))
| (0xff00000000000000L & ((long)bytes[7] << 56));
}
public static int bytes2Int(byte[]bytes) {
return (bytes[0]&0xff) << 24
| (bytes[1]&0xff) << 16
| (bytes[2]&0xff) << 8
| (bytes[3]&0xff);
}
public static int bytes2IntBigEndian(byte[]bytes) {
return (bytes[3]&0xff) << 24
| (bytes[2]&0xff) << 16
| (bytes[1]&0xff) << 8
| (bytes[0]&0xff);
}
public static short bytes2Short(byte[]bytes) {
return (short)((bytes[0]&0xff) << 8
| (bytes[1]&0xff));
}
public static int bytes2ShortBigEndian(byte[]bytes) {
return (short)((bytes[1]&0xff) << 8
| (bytes[0]&0xff));
}
}
另外ByteBuffer好像也有对应的处理方法，写了一些简单的测试方法代码如下：
private static ByteBuffer shortBuffer = ByteBuffer.allocate(2);
private static ByteBuffer intBuffer = ByteBuffer.allocate(4);
private static ByteBuffer longBuffer = ByteBuffer.allocate(8);
public static long bytes2Short(byte[] bytes) {
shortBuffer.clear();
shortBuffer.put(bytes, 0, bytes.length);
shortBuffer.flip();//need flip
return shortBuffer.getShort();
}
public static long bytes2ShortBigEndian(byte[] bytes) {
shortBuffer.clear();
shortBuffer.order(ByteOrder.LITTLE_ENDIAN);
shortBuffer.put(bytes, 0, bytes.length);
shortBuffer.flip();//need flip
return shortBuffer.getShort();
}
public static long bytes2ShortBigEndian(byte[] bytes, int pos) {
shortBuffer.clear();
shortBuffer.order(ByteOrder.LITTLE_ENDIAN);
shortBuffer.put(bytes, pos, 2);
shortBuffer.flip();//need flip
return shortBuffer.getShort();
}
public static long bytes2Int(byte[] bytes) {
intBuffer.clear();
intBuffer.put(bytes, 0, bytes.length);
intBuffer.flip();//need flip
return intBuffer.getInt();
}
public static long bytes2IntBigEndian(byte[] bytes) {
intBuffer.clear();
intBuffer.order(ByteOrder.LITTLE_ENDIAN);
intBuffer.put(bytes, 0, bytes.length);
intBuffer.flip();//need flip
return intBuffer.getInt();
}
public static long bytes2IntBigEndian(byte[] bytes, int pos) {
intBuffer.clear();
intBuffer.order(ByteOrder.LITTLE_ENDIAN);
intBuffer.put(bytes, pos, 4);
intBuffer.flip();//need flip
return intBuffer.getInt();
}
public static long bytes2Long(byte[] bytes) {
longBuffer.clear();
longBuffer.put(bytes, 0, bytes.length);
longBuffer.flip();//need flip
return longBuffer.getLong();
}
public static long bytes2LongBigEndian(byte[] bytes) {
longBuffer.clear();
longBuffer.order(ByteOrder.LITTLE_ENDIAN);
longBuffer.put(bytes, 0, bytes.length);
longBuffer.flip();//need flip
return longBuffer.getLong();
}
public static long bytes2LongBigEndian(byte[] bytes, int pos) {
longBuffer.clear();
longBuffer.order(ByteOrder.LITTLE_ENDIAN);
longBuffer.put(bytes, pos, 8);
longBuffer.flip();//need flip
return longBuffer.getLong();
}