Java 中 byte、byte 数组和 int、long 之间的转换
Java 中 byte 和 int 之间的转换源码：
import java.nio.ByteBuffer;public class Test {private static ByteBuffer buffer = ByteBuffer.allocate(8); public static void main(String[] args) {//测试 int 转 byteint int0 = 234;byte byte0 = intToByte(int0);System.out.println("byte0=" + byte0);//byte0=-22//测试 byte 转 intint int1 = byteToInt(byte0);System.out.println("int1=" + int1);//int1=234//测试 int 转 byte 数组int int2 = 1417;byte[] bytesInt = intToByteArray(int2);System.out.println("bytesInt=" + bytesInt);//bytesInt=[B@de6ced//测试 byte 数组转 intint int3 = byteArrayToInt(bytesInt);System.out.println("int3=" + int3);//int3=1417//测试 long 转 byte 数组long long1 = 2223;byte[] bytesLong = longToBytes(long1);System.out.println("bytes=" + bytesLong);//bytes=[B@c17164//测试 byte 数组 转 longlong long2 = bytesToLong(bytesLong);System.out.println("long2=" + long2);//long2=2223}//byte 与 int 的相互转换public static byte intToByte(int x) {return (byte) x;}public static int byteToInt(byte b) {//Java 总是把 byte 当做有符处理；我们可以通过将其和 0xFF 进行二进制与得到它的无符值return b & 0xFF;}//byte 数组与 int 的相互转换public static int byteArrayToInt(byte[] b) { return b[3] & 0xFF | (b[2] & 0xFF) << 8 | (b[1] & 0xFF) << 16 | (b[0] & 0xFF) << 24;}public static byte[] intToByteArray(int a) { return new byte[] { (byte) ((a >> 24) & 0xFF), (byte) ((a >> 16) & 0xFF), (byte) ((a >> 8) & 0xFF), (byte) (a & 0xFF) };}//byte 数组与 long 的相互转换 public static byte[] longToBytes(long x) { buffer.putLong(0, x); return buffer.array(); } public static long bytesToLong(byte[] bytes) { buffer.put(bytes, 0, bytes.length); buffer.flip();//need flip return buffer.getLong(); }}