short,int,long与byte数组之间的转换

编程技术  /  houtizong 发布于 3年前   85

package com.test; import java.nio.ByteBuffer; public class ByteUtil {     /**      * @param args      */     public static void main(String[] args) {         test2();     }     public static void test2()     {         short s = -20;         byte[] b = new byte[2];         putReverseBytesShort(b, s, 0);         ByteBuffer buf = ByteBuffer.allocate(2);         buf.put(b);         buf.flip();         System.out.println(getReverseBytesShort(b, 0));         System.out.println(Short.reverseBytes(buf.getShort()));         System.out.println("***************************");         int i = -40;         b = new byte[4];         putReverseBytesInt(b, i, 0);         buf = ByteBuffer.allocate(4);         buf.put(b);         buf.flip();         System.out.println(getReverseBytesInt(b, 0));         System.out.println(Integer.reverseBytes(buf.getInt()));         System.out.println("***************************");         long l = -50;         b = new byte[8];         putReverseBytesLong(b, l, 0);         buf = ByteBuffer.allocate(8);         buf.put(b);         buf.flip();         System.out.println(getReverseBytesLong(b, 0));         System.out.println(Long.reverseBytes(buf.getLong()));         System.out.println("***************************");     }     public static void test1()     {         short s = -20;         byte[] b = new byte[2];         putShort(b, s, 0);         ByteBuffer buf = ByteBuffer.allocate(2);         buf.put(b);         buf.flip();         System.out.println(getShort(b, 0));         System.out.println(buf.getShort());         System.out.println("***************************");         int i = -40;         b = new byte[4];         putInt(b, i, 0);         buf = ByteBuffer.allocate(4);         buf.put(b);         buf.flip();         System.out.println(getInt(b, 0));         System.out.println(buf.getInt());         System.out.println("***************************");         long l = -50;         b = new byte[8];         putLong(b, l, 0);         buf = ByteBuffer.allocate(8);         buf.put(b);         buf.flip();         System.out.println(getLong(b, 0));         System.out.println(buf.getLong());         System.out.println("***************************");     }     public static void putShort(byte b[], short s, int index) {         b[index] = (byte) (s >> 8);         b[index + 1] = (byte) (s >> 0);     }     public static void putReverseBytesShort(byte b[], short s, int index) {         b[index] = (byte) (s >> 0);         b[index + 1] = (byte) (s >> 8);     }     public static short getShort(byte[] b, int index) {         return (short) (((b[index] << 8) | b[index + 1] & 0xff));     }     public static short getReverseBytesShort(byte[] b, int index) {         return (short) (((b[index+1] << 8) | b[index] & 0xff));     }     // ///////////////////////////////////////////////////////     public static void putInt(byte[] bb, int x, int index) {         bb[index + 0] = (byte) (x >> 24);         bb[index + 1] = (byte) (x >> 16);         bb[index + 2] = (byte) (x >> 8);         bb[index + 3] = (byte) (x >> 0);     }     public static void putReverseBytesInt(byte[] bb, int x, int index) {         bb[index + 3] = (byte) (x >> 24);         bb[index + 2] = (byte) (x >> 16);         bb[index + 1] = (byte) (x >> 8);         bb[index + 0] = (byte) (x >> 0);     }     public static int getInt(byte[] bb, int index) {         return (int) ((((bb[index + 0] & 0xff) << 24)                 | ((bb[index + 1] & 0xff) << 16)                 | ((bb[index + 2] & 0xff) << 8) | ((bb[index + 3] & 0xff) << 0)));     }     public static int getReverseBytesInt(byte[] bb, int index) {         return (int) ((((bb[index + 3] & 0xff) << 24)                 | ((bb[index + 2] & 0xff) << 16)                 | ((bb[index + 1] & 0xff) << 8) | ((bb[index + 0] & 0xff) << 0)));     }     // /////////////////////////////////////////////////////////     public static void putLong(byte[] bb, long x, int index) {         bb[index + 0] = (byte) (x >> 56);         bb[index + 1] = (byte) (x >> 48);         bb[index + 2] = (byte) (x >> 40);         bb[index + 3] = (byte) (x >> 32);         bb[index + 4] = (byte) (x >> 24);         bb[index + 5] = (byte) (x >> 16);         bb[index + 6] = (byte) (x >> 8);         bb[index + 7] = (byte) (x >> 0);     }     public static void putReverseBytesLong(byte[] bb, long x, int index) {         bb[index + 7] = (byte) (x >> 56);         bb[index + 6] = (byte) (x >> 48);         bb[index + 5] = (byte) (x >> 40);         bb[index + 4] = (byte) (x >> 32);         bb[index + 3] = (byte) (x >> 24);         bb[index + 2] = (byte) (x >> 16);         bb[index + 1] = (byte) (x >> 8);         bb[index + 0] = (byte) (x >> 0);     }     public static long getLong(byte[] bb, int index) {         return ((((long) bb[index + 0] & 0xff) << 56)                 | (((long) bb[index + 1] & 0xff) << 48)                 | (((long) bb[index + 2] & 0xff) << 40)                 | (((long) bb[index + 3] & 0xff) << 32)                 | (((long) bb[index + 4] & 0xff) << 24)                 | (((long) bb[index + 5] & 0xff) << 16)                 | (((long) bb[index + 6] & 0xff) << 8) | (((long) bb[index + 7] & 0xff) << 0));     }     public static long getReverseBytesLong(byte[] bb, int index) {         return ((((long) bb[index + 7] & 0xff) << 56)                 | (((long) bb[index + 6] & 0xff) << 48)                 | (((long) bb[index + 5] & 0xff) << 40)                 | (((long) bb[index + 4] & 0xff) << 32)                 | (((long) bb[index + 3] & 0xff) << 24)                 | (((long) bb[index + 2] & 0xff) << 16)                 | (((long) bb[index + 1] & 0xff) << 8) | (((long) bb[index + 0] & 0xff) << 0));     } }