Java中byte、byte数组与int、long的转换详解

java;">//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; } 

//测试 int 转 byte int int0 = 234; byte byte0 = intToByte(int0); System.out.println("byte0=" + byte0);//byte0=-22 //测试 byte 转 int int int1 = byteToInt(byte0); System.out.println("int1=" + int1);//int1=234 

//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)  }; } 

//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 int int int3 = byteArrayToInt(bytesInt); System.out.println("int3=" + int3);//int3=1417 

private static ByteBuffer buffer = ByteBuffer.allocate(8); //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();  } 

//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 long long long2 = bytesToLong(bytesLong); System.out.println("long2=" + long2);//long2=2223 

import java.nio.ByteBuffer;   public class Test {   private static ByteBuffer buffer = ByteBuffer.allocate(8);   public static void main(String[] args) {    //测试 int 转 byte  int int0 = 234;  byte byte0 = intToByte(int0);  System.out.println("byte0=" + byte0);//byte0=-22  //测试 byte 转 int  int 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 int  int 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 long  long 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();  }  } 

byte0=-22int1=234bytesInt=[B@de6cedint3=1417bytes=[B@c17164long2=2223