In network programming, due to the need to save bandwidth or encoding, it is usually necessary to process long and int natively instead of converting to string.

public class ByteOrderUtils {
public static byte[] int2byte(int res) { 
byte[] targets = new byte[4]; 
targets[3] = (byte) (res & 0xff);// 最低位 
targets[2] = (byte) ((res >> 8) & 0xff);// 次低位 
targets[1] = (byte) ((res >> 16) & 0xff);// 次高位 
targets[0] = (byte) (res >>> 24);// 最高位,無(wú)符號(hào)右移。 
return targets; 
}
public static int byteArrayToInt(byte[] b){ 
byte[] a = new byte[4]; 
int i = a.length - 1,j = b.length - 1; 
for (; i >= 0 ; i--,j--) {//從b的尾部(即int值的低位)開始copy數(shù)據(jù) 
if(j >= 0) 
a[i] = b[j]; 
else 
a[i] = 0;//如果b.length不足4,則將高位補(bǔ)0 
} 
int v0 = (a[0] & 0xff) << 24;//&0xff將byte值無(wú)差異轉(zhuǎn)成int,避免Java自動(dòng)類型提升后,會(huì)保留高位的符號(hào)位 
int v1 = (a[1] & 0xff) << 16; 
int v2 = (a[2] & 0xff) << 8; 
int v3 = (a[3] & 0xff) ; 
return v0 + v1 + v2 + v3; 
}
public static byte[] long2byte(long res) { 
byte[] buffer = new byte[8]; 
for (int i = 0; i < 8; i++) { 
int offset = 64 - (i + 1) * 8; 
buffer[i] = (byte) ((res >> offset) & 0xff); 
}
return buffer;
}
public static long byteArrayToLong(byte[] b){ 
long values = 0; 
for (int i = 0; i < 8; i++) { 
values <<= 8; values|= (b[i] & 0xff); 
} 
return values; 
}
}