java int to byte and long to byte

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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) { <br/>byte[] targets = new byte[4]; <br/><br/>targets[3] = (byte) (res & 0xff); // lowest Bit <br/>targets[2] = (byte) ((res >> 8) & 0xff);// Second low bit <br/>targets[1] = (byte) ((res >> 16) & 0xff);/ / Second highest bit <br/>targets[0] = (byte) (res >>> 24); // Highest bit, unsigned right shift. <br/>return targets; <br/>}

public static int byteArrayToInt(byte[] b){ <br/>byte[] a = new byte[4]; <br/>int i = a.length - 1,j = b.length - 1; <br/> for (; i >= 0 ; i--,j--) {//Copy data starting from the tail of b (that is, the low bit of the int value) <br/>if(j >= 0) <br/>a[i] = b [j]; <br/>else <br/>a[i] = 0;//If b.length is less than 4, fill the high bit with 0 <br/>} <br/>int v0 = (a[0] & 0xff) << 24;// &0xff converts the byte value into int without any difference to avoid Java's automatic type promotion and retain the high-order sign bit <br/>int v1 = (a[1] & 0xff) << 16; <br/>int v2 = (a[2] & 0xff) << 8; <br/>int v3 = (a[3] & 0xff) ; <br/>return v0 + v1 + v2 + v3; <br/>}<br/><br/>public static byte[] long2byte(long res) { <br/>byte[ ] buffer = new byte[8]; <br/>for (int i = 0; i < 8; i++) { <br/>int offset = 64 - (i + 1) * 8; <br/>buffer[i] = (byte) (( res >> offset) & 0xff); <br/>}<br/>return buffer;<br/>}

public static long byteArrayToLong(byte[] b){ <br/>long values ​​= 0; <br/>for (int i = 0; i < 8 ; i++) { <br/>values ​​<<= 8; values|= (b[i] & 0xff); <br/>} <br/>return values; <br/>}

}

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