版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/FlyLikeButterfly/article/details/83024756
大端：高位字节放在内存的低地址位置；
小端：低位字节放在内存的低地址位置；
东拼西凑的Demo：
/**
* createtime:2018年6月4日下午6:24:01
*/
package cn.zectec.synchroserver.codec;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
/**
* @author XWF
*
*/
public class CodecUtil {
/**
* 向将bytes添加到另一个bytes结尾，并返回位置
* @param buff 目标数组
* @param pos 目标数组放置的起始位置
* @param lens 添加的长度
* @param dx 要添加的数组
* @return lens添加的长度
*/
public static int addToBuff(byte[] buff, int pos, int lens, byte[] dx) {
System.arraycopy(dx, 0, buff, pos, lens);
return lens;
}
/**
* 获得bytes的一段数据
* @param buff 原byte数组
* @param startPos 起始位置
* @param lenth 获取的长度
* @return 返回获得的byte数组
*/
public static byte[] getFromBuff(byte[] buff,int startPos,int lenth) {
byte[] bytes = new byte[lenth];
System.arraycopy(buff, startPos, bytes, 0, lenth);
return bytes;
}
/**
* double转byte数组，小端模式
* @param d
* @return
*/
public static byte[] doubleToBytes_Little(double d){
long l = Double.doubleToLongBits(d);
byte b[] = new byte[8];
b[7] = (byte) (0xff & (l >> 56));
b[6] = (byte) (0xff & (l >> 48));
b[5] = (byte) (0xff & (l >> 40));
b[4] = (byte) (0xff & (l >> 32));
b[3] = (byte) (0xff & (l >> 24));
b[2] = (byte) (0xff & (l >> 16));
b[1] = (byte) (0xff & (l >> 8));
b[0] = (byte) (0xff & l);
return b;
}
/**
* double转byte数组，大端模式
* @param d
* @return
*/
public static byte[] doubleToBytes_Big(double d){
long l = Double.doubleToLongBits(d);
byte b[] = new byte[8];
b[0] = (byte) (0xff & (l >> 56));
b[1] = (byte) (0xff & (l >> 48));
b[2] = (byte) (0xff & (l >> 40));
b[3] = (byte) (0xff & (l >> 32));
b[4] = (byte) (0xff & (l >> 24));
b[5] = (byte) (0xff & (l >> 16));
b[6] = (byte) (0xff & (l >> 8));
b[7] = (byte) (0xff & l);
return b;
}
/**
* byte数组转double
* @param bytes 8位byte数组
* @param littleEndian 是否是小端模式
* @return
*/
public static double bytesToDouble(byte[] bytes, boolean littleEndian) {
ByteBuffer buffer = ByteBuffer.wrap(bytes,0,8);
if(littleEndian){
// ByteBuffer.order(ByteOrder) 方法指定字节序,即大小端模式(BIG_ENDIAN/LITTLE_ENDIAN)
// ByteBuffer 默认为大端(BIG_ENDIAN)模式
buffer.order(ByteOrder.LITTLE_ENDIAN);
}
long l = buffer.getLong();
return Double.longBitsToDouble(l);
}
/**
* long转byte数组，小端模式
* @param l
* @return
*/
public static byte[] longToBytes_Little(long l) {
byte b[] = new byte[8];
b[7] = (byte) (0xff & (l >> 56));
b[6] = (byte) (0xff & (l >> 48));
b[5] = (byte) (0xff & (l >> 40));
b[4] = (byte) (0xff & (l >> 32));
b[3] = (byte) (0xff & (l >> 24));
b[2] = (byte) (0xff & (l >> 16));
b[1] = (byte) (0xff & (l >> 8));
b[0] = (byte) (0xff & l);
return b;
}
/**
* long转byte数组，大端模式
* @param l
* @return
*/
public static byte[] longToBytes_Big(long l) {
byte b[] = new byte[8];
b[0] = (byte) (0xff & (l >> 56));
b[1] = (byte) (0xff & (l >> 48));
b[2] = (byte) (0xff & (l >> 40));
b[3] = (byte) (0xff & (l >> 32));
b[4] = (byte) (0xff & (l >> 24));
b[5] = (byte) (0xff & (l >> 16));
b[6] = (byte) (0xff & (l >> 8));
b[7] = (byte) (0xff & l);
return b;
}
/**
* byte数组转long
* @param bytes 8位的byte数组
* @param littleEndian 是否是小端模式
* @return
* @throws Exception
*/
public static long bytesToLong(byte[] bytes, boolean littleEndian) throws Exception {
if(bytes.length != 8) {
throw new Exception("参数错误，无法解析。");
}
ByteBuffer buffer = ByteBuffer.wrap(bytes,0,8);
if(littleEndian){
// ByteBuffer.order(ByteOrder) 方法指定字节序,即大小端模式(BIG_ENDIAN/LITTLE_ENDIAN)
// ByteBuffer 默认为大端(BIG_ENDIAN)模式
buffer.order(ByteOrder.LITTLE_ENDIAN);
}
return buffer.getLong();
}
/**
* int转byte数组 ,小端
* @param num
* @return
*/
public static byte[] intToBytes_Little(int num){
byte[] result = new byte[4];
result[0] = (byte)((num >>> 0) & 0xff);
result[1] = (byte)((num >>> 8)& 0xff );
result[2] = (byte)((num >>> 16) & 0xff );
result[3] = (byte)((num >>> 24) & 0xff );
return result;
}
/**
* int转byte数组 ,大端
* @param num
* @return
*/
public static byte[] intToBytes_Big(int num){
byte[] result = new byte[4];
result[0] = (byte)((num >>> 24) & 0xff);
result[1] = (byte)((num >>> 16)& 0xff );
result[2] = (byte)((num >>> 8) & 0xff );
result[3] = (byte)((num >>> 0) & 0xff );
return result;
}
/**
* byte数组转int,小端
* @param bytes
* @return
*/
public static int bytesToInt_Little(byte[] bytes){
int result = 0;
if(bytes.length == 4){
int a = (bytes[0] & 0xff) << 0;
int b = (bytes[1] & 0xff) << 8;
int c = (bytes[2] & 0xff) << 16;
int d = (bytes[3] & 0xff) << 24;
result = a | b | c | d;
}
return result;
}
/**
* byte数组转int,大端
* @param bytes
* @return
*/
public static int bytesToInt_Big(byte[] bytes){
int result = 0;
if(bytes.length == 4){
int a = (bytes[0] & 0xff) << 24;
int b = (bytes[1] & 0xff) << 16;
int c = (bytes[2] & 0xff) << 8;
int d = (bytes[3] & 0xff) << 0;
result = a | b | c | d;
}
return result;
}
/**
* byte数组转十六进制
* @param bytes
* @return
*/
public static String bytesToHex(byte[] bytes) {
StringBuilder buf = new StringBuilder(bytes.length * 2);
for(byte b : bytes) { // 使用String的format方法进行转换
buf.append(String.format("%02x", new Integer(b & 0xff)));
}
return buf.toString();
}
/**
* 十六进制转byte数组
* @param str
* @return
*/
public static byte[] hexToBytes(String str) {
if(str == null || str.trim().equals("")) {
return new byte[0];
}
byte[] bytes = new byte[str.length() / 2];
for(int i = 0; i < str.length() / 2; i++) {
String subStr = str.substring(i * 2, i * 2 + 2);
bytes[i] = (byte) Integer.parseInt(subStr, 16);
}
return bytes;
}
}