java的int、char、long、float、double对byte的转换

java的int、char、long、float、double对byte的转换，在通信的时候会用到

2011-07-18 16:53:40 我来说两句
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Java代码

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);

}

}