java中byte数组与int，long，short间的转换

迈不过友情╰ 2022-09-17 11:28 265阅读 0赞

package com.util;
    
    /**
     * 
     * <ul>
     * <li>文件名称: com.born.util.ByteUtil.java</li>
     * <li>文件描述: byte转换工具</li>
     * <li>版权所有: 版权所有(C)2001-2006</li>
     * <li>公 司: bran</li>
     * <li>内容摘要:</li>
     * <li>其他说明:</li>
     * <li>完成日期：2011-7-18</li>
     * <li>修改记录0：无</li>
     * </ul>
     * 
     * @version 1.0
     * @author 许力多
     */
    public class ByteUtil {
    	/**
    	 * 转换short为byte
    	 * 
    	 * @param b
    	 * @param s
    	 *            需要转换的short
    	 * @param index
    	 */
    	public static void putShort(byte b[], short s, int index) {
    		b[index + 1] = (byte) (s >> 8);
    		b[index + 0] = (byte) (s >> 0);
    	}
    
    	/**
    	 * 通过byte数组取到short
    	 * 
    	 * @param b
    	 * @param index
    	 *            第几位开始取
    	 * @return
    	 */
    	public static short getShort(byte[] b, int index) {
    		return (short) (((b[index + 1] << 8) | b[index + 0] & 0xff));
    	}
    
    	/**
    	 * 转换int为byte数组
    	 * 
    	 * @param bb
    	 * @param x
    	 * @param index
    	 */
    	public static void putInt(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);
    	}
    
    	/**
    	 * 通过byte数组取到int
    	 * 
    	 * @param bb
    	 * @param index
    	 *            第几位开始
    	 * @return
    	 */
    	public static int getInt(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)));
    	}
    
    	/**
    	 * 转换long型为byte数组
    	 * 
    	 * @param bb
    	 * @param x
    	 * @param index
    	 */
    	public static void putLong(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);
    	}
    
    	/**
    	 * 通过byte数组取到long
    	 * 
    	 * @param bb
    	 * @param index
    	 * @return
    	 */
    	public static long getLong(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));
    	}
    
    	/**
    	 * 字符到字节转换
    	 * 
    	 * @param ch
    	 * @return
    	 */
    	public static void putChar(byte[] bb, char ch, int index) {
    		int temp = (int) ch;
    		// byte[] b = new byte[2];
    		for (int i = 0; i < 2; i ++ ) {
    			bb[index + i] = new Integer(temp & 0xff).byteValue(); // 将最高位保存在最低位
    			temp = temp >> 8; // 向右移8位
    		}
    	}
    
    	/**
    	 * 字节到字符转换
    	 * 
    	 * @param b
    	 * @return
    	 */
    	public static char getChar(byte[] b, int index) {
    		int s = 0;
    		if (b[index + 1] > 0)
    			s += b[index + 1];
    		else
    			s += 256 + b[index + 0];
    		s *= 256;
    		if (b[index + 0] > 0)
    			s += b[index + 1];
    		else
    			s += 256 + b[index + 0];
    		char ch = (char) s;
    		return ch;
    	}
    
    	/**
    	 * float转换byte
    	 * 
    	 * @param bb
    	 * @param x
    	 * @param index
    	 */
    	public static void putFloat(byte[] bb, float x, int index) {
    		// byte[] b = new byte[4];
    		int l = Float.floatToIntBits(x);
    		for (int i = 0; i < 4; i++) {
    			bb[index + i] = new Integer(l).byteValue();
    			l = l >> 8;
    		}
    	}
    
    	/**
    	 * 通过byte数组取得float
    	 * 
    	 * @param bb
    	 * @param index
    	 * @return
    	 */
    	public static float getFloat(byte[] b, int index) {
    		int l;
    		l = b[index + 0];
    		l &= 0xff;
    		l |= ((long) b[index + 1] << 8);
    		l &= 0xffff;
    		l |= ((long) b[index + 2] << 16);
    		l &= 0xffffff;
    		l |= ((long) b[index + 3] << 24);
    		return Float.intBitsToFloat(l);
    	}
    
    	/**
    	 * double转换byte
    	 * 
    	 * @param bb
    	 * @param x
    	 * @param index
    	 */
    	public static void putDouble(byte[] bb, double x, int index) {
    		// byte[] b = new byte[8];
    		long l = Double.doubleToLongBits(x);
    		for (int i = 0; i < 4; i++) {
    			bb[index + i] = new Long(l).byteValue();
    			l = l >> 8;
    		}
    	}
    
    	/**
    	 * 通过byte数组取得float
    	 * 
    	 * @param bb
    	 * @param index
    	 * @return
    	 */
    	public static double getDouble(byte[] b, int index) {
    		long l;
    		l = b[0];
    		l &= 0xff;
    		l |= ((long) b[1] << 8);
    		l &= 0xffff;
    		l |= ((long) b[2] << 16);
    		l &= 0xffffff;
    		l |= ((long) b[3] << 24);
    		l &= 0xffffffffl;
    		l |= ((long) b[4] << 32);
    		l &= 0xffffffffffl;
    		l |= ((long) b[5] << 40);
    		l &= 0xffffffffffffl;
    		l |= ((long) b[6] << 48);
    		l &= 0xffffffffffffffl;
    		l |= ((long) b[7] << 56);
    		return Double.longBitsToDouble(l);
    	}
    }

public class DataTypeChangeHelper {
    	/**
    	 * 将一个单字节的byte转换成32位的int
    	 * 
    	 * @param b
    	 *            byte
    	 * @return convert result
    	 */
    	public static int unsignedByteToInt(byte b) {
    		return (int) b & 0xFF;
    	}
    
    	/**
    	 * 将一个单字节的Byte转换成十六进制的数
    	 * 
    	 * @param b
    	 *            byte
    	 * @return convert result
    	 */
    	public static String byteToHex(byte b) {
    		int i = b & 0xFF;
    		return Integer.toHexString(i);
    	}
    
    	/**
    	 * 将一个4byte的数组转换成32位的int
    	 * 
    	 * @param buf
    	 *            bytes buffer
    	 * @param byte[]中开始转换的位置
    	 * @return convert result
    	 */
    	public static long unsigned4BytesToInt(byte[] buf, int pos) {
    		int firstByte = 0;
    		int secondByte = 0;
    		int thirdByte = 0;
    		int fourthByte = 0;
    		int index = pos;
    		firstByte = (0x000000FF & ((int) buf[index]));
    		secondByte = (0x000000FF & ((int) buf[index + 1]));
    		thirdByte = (0x000000FF & ((int) buf[index + 2]));
    		fourthByte = (0x000000FF & ((int) buf[index + 3]));
    		index = index + 4;
    		return ((long) (firstByte << 24 | secondByte << 16 | thirdByte << 8 | fourthByte)) & 0xFFFFFFFFL;
    	}
    
    	/**
    	 * 将16位的short转换成byte数组
    	 * 
    	 * @param s
    	 *            short
    	 * @return byte[] 长度为2
    	 * */
    	public static byte[] shortToByteArray(short s) {
    		byte[] targets = new byte[2];
    		for (int i = 0; i < 2; i++) {
    			int offset = (targets.length - 1 - i) * 8;
    			targets[i] = (byte) ((s >>> offset) & 0xff);
    		}
    		return targets;
    	}
    
    	/**
    	 * 将32位整数转换成长度为4的byte数组
    	 * 
    	 * @param s
    	 *            int
    	 * @return byte[]
    	 * */
    	public static byte[] intToByteArray(int s) {
    		byte[] targets = new byte[2];
    		for (int i = 0; i < 4; i++) {
    			int offset = (targets.length - 1 - i) * 8;
    			targets[i] = (byte) ((s >>> offset) & 0xff);
    		}
    		return targets;
    	}
    
    	/**
    	 * long to byte[]
    	 * 
    	 * @param s
    	 *            long
    	 * @return byte[]
    	 * */
    	public static byte[] longToByteArray(long s) {
    		byte[] targets = new byte[2];
    		for (int i = 0; i < 8; i++) {
    			int offset = (targets.length - 1 - i) * 8;
    			targets[i] = (byte) ((s >>> offset) & 0xff);
    		}
    		return targets;
    	}
    
    	/**32位int转byte[]*/
    	public static byte[] int2byte(int res) {
    		byte[] targets = new byte[4];
    		targets[0] = (byte) (res & 0xff);// 最低位
    		targets[1] = (byte) ((res >> 8) & 0xff);// 次低位
    		targets[2] = (byte) ((res >> 16) & 0xff);// 次高位
    		targets[3] = (byte) (res >>> 24);// 最高位,无符号右移。
    		return targets;
    	}
    
    	/**
    	 * 将长度为2的byte数组转换为16位int
    	 * 
    	 * @param res
    	 *            byte[]
    	 * @return int
    	 * */
    	public static int byte2int(byte[] res) {
    		// res = InversionByte(res);
    		// 一个byte数据左移24位变成0x??000000，再右移8位变成0x00??0000
    		int targets = (res[0] & 0xff) | ((res[1] << 8) & 0xff00); // | 表示安位或
    		return targets;
    	}
    }