java中byte数组与int，long，short间的转换

1 package com.util;
2
3 /**
4  *
5  * <ul>
6  * <li>文件名称: com.born.util.ByteUtil.java</li>
7  * <li>文件描述: byte转换工具</li>
8  * <li>版权所有: 版权所有(C)2001-2006</li>
9  * <li>公 司: bran</li>
10  * <li>内容摘要:</li>
11  * <li>其他说明:</li>
12  * <li>完成日期：2011-7-18</li>
13  * <li>修改记录0：无</li>
14  * </ul>
15  *
16  * @version 1.0
17  * @author 许力多
18  */
19 public class ByteUtil {
20     /**
21      * 转换short为byte
22      *
23      * @param b
24      * @param s
25      *            需要转换的short
26      * @param index
27      */
28     public static void putShort(byte b[], short s, int index) {
29         b[index + 1] = (byte) (s >> 8);
30         b[index + 0] = (byte) (s >> 0);
31     }
32
33     /**
34      * 通过byte数组取到short
35      *
36      * @param b
37      * @param index
38      *            第几位开始取
39      * @return
40      */
41     public static short getShort(byte[] b, int index) {
42         return (short) (((b[index + 1] << 8) | b[index + 0] & 0xff));
43     }
44
45     /**
46      * 转换int为byte数组
47      *
48      * @param bb
49      * @param x
50      * @param index
51      */
52     public static void putInt(byte[] bb, int x, int index) {
53         bb[index + 3] = (byte) (x >> 24);
54         bb[index + 2] = (byte) (x >> 16);
55         bb[index + 1] = (byte) (x >> 8);
56         bb[index + 0] = (byte) (x >> 0);
57     }
58
59     /**
60      * 通过byte数组取到int
61      *
62      * @param bb
63      * @param index
64      *            第几位开始
65      * @return
66      */
67     public static int getInt(byte[] bb, int index) {
68         return (int) ((((bb[index + 3] & 0xff) << 24)
69                 | ((bb[index + 2] & 0xff) << 16)
70                 | ((bb[index + 1] & 0xff) << 8) | ((bb[index + 0] & 0xff) << 0)));
71     }
72
73     /**
74      * 转换long型为byte数组
75      *
76      * @param bb
77      * @param x
78      * @param index
79      */
80     public static void putLong(byte[] bb, long x, int index) {
81         bb[index + 7] = (byte) (x >> 56);
82         bb[index + 6] = (byte) (x >> 48);
83         bb[index + 5] = (byte) (x >> 40);
84         bb[index + 4] = (byte) (x >> 32);
85         bb[index + 3] = (byte) (x >> 24);
86         bb[index + 2] = (byte) (x >> 16);
87         bb[index + 1] = (byte) (x >> 8);
88         bb[index + 0] = (byte) (x >> 0);
89     }
90
91     /**
92      * 通过byte数组取到long
93      *
94      * @param bb
95      * @param index
96      * @return
97      */
98     public static long getLong(byte[] bb, int index) {
99         return ((((long) bb[index + 7] & 0xff) << 56)
100                 | (((long) bb[index + 6] & 0xff) << 48)
101                 | (((long) bb[index + 5] & 0xff) << 40)
102                 | (((long) bb[index + 4] & 0xff) << 32)
103                 | (((long) bb[index + 3] & 0xff) << 24)
104                 | (((long) bb[index + 2] & 0xff) << 16)
105                 | (((long) bb[index + 1] & 0xff) << 8) | (((long) bb[index + 0] & 0xff) << 0));
106     }
107
108     /**
109      * 字符到字节转换
110      *
111      * @param ch
112      * @return
113      */
114     public static void putChar(byte[] bb, char ch, int index) {
115         int temp = (int) ch;
116         // byte[] b = new byte[2];
117         for (int i = 0; i < 2; i ++ ) {
118             bb[index + i] = new Integer(temp & 0xff).byteValue(); // 将最高位保存在最低位
119             temp = temp >> 8; // 向右移8位
120         }
121     }
122
123     /**
124      * 字节到字符转换
125      *
126      * @param b
127      * @return
128      */
129     public static char getChar(byte[] b, int index) {
130         int s = 0;
131         if (b[index + 1] > 0)
132             s += b[index + 1];
133         else
134             s += 256 + b[index + 0];
135         s *= 256;
136         if (b[index + 0] > 0)
137             s += b[index + 1];
138         else
139             s += 256 + b[index + 0];
140         char ch = (char) s;
141         return ch;
142     }
143
144     /**
145      * float转换byte
146      *
147      * @param bb
148      * @param x
149      * @param index
150      */
151     public static void putFloat(byte[] bb, float x, int index) {
152         // byte[] b = new byte[4];
153         int l = Float.floatToIntBits(x);
154         for (int i = 0; i < 4; i++) {
155             bb[index + i] = new Integer(l).byteValue();
156             l = l >> 8;
157         }
158     }
159
160     /**
161      * 通过byte数组取得float
162      *
163      * @param bb
164      * @param index
165      * @return
166      */
167     public static float getFloat(byte[] b, int index) {
168         int l;
169         l = b[index + 0];
170         l &= 0xff;
171         l |= ((long) b[index + 1] << 8);
172         l &= 0xffff;
173         l |= ((long) b[index + 2] << 16);
174         l &= 0xffffff;
175         l |= ((long) b[index + 3] << 24);
176         return Float.intBitsToFloat(l);
177     }
178
179     /**
180      * double转换byte
181      *
182      * @param bb
183      * @param x
184      * @param index
185      */
186     public static void putDouble(byte[] bb, double x, int index) {
187         // byte[] b = new byte[8];
188         long l = Double.doubleToLongBits(x);
189         for (int i = 0; i < 4; i++) {
190             bb[index + i] = new Long(l).byteValue();
191             l = l >> 8;
192         }
193     }
194
195     /**
196      * 通过byte数组取得float
197      *
198      * @param bb
199      * @param index
200      * @return
201      */
202     public static double getDouble(byte[] b, int index) {
203         long l;
204         l = b[0];
205         l &= 0xff;
206         l |= ((long) b[1] << 8);
207         l &= 0xffff;
208         l |= ((long) b[2] << 16);
209         l &= 0xffffff;
210         l |= ((long) b[3] << 24);
211         l &= 0xffffffffl;
212         l |= ((long) b[4] << 32);
213         l &= 0xffffffffffl;
214         l |= ((long) b[5] << 40);
215         l &= 0xffffffffffffl;
216         l |= ((long) b[6] << 48);
217         l &= 0xffffffffffffffl;
218         l |= ((long) b[7] << 56);
219         return Double.longBitsToDouble(l);
220     }
221 }

1 public class DataTypeChangeHelper {
2     /**
3      * 将一个单字节的byte转换成32位的int
4      *
5      * @param b
6      *            byte
7      * @return convert result
8      */
9     public static int unsignedByteToInt(byte b) {
10         return (int) b & 0xFF;
11     }
12
13     /**
14      * 将一个单字节的Byte转换成十六进制的数
15      *
16      * @param b
17      *            byte
18      * @return convert result
19      */
20     public static String byteToHex(byte b) {
21         int i = b & 0xFF;
22         return Integer.toHexString(i);
23     }
24
25     /**
26      * 将一个4byte的数组转换成32位的int
27      *
28      * @param buf
29      *            bytes buffer
30      * @param byte[]中开始转换的位置
31      * @return convert result
32      */
33     public static long unsigned4BytesToInt(byte[] buf, int pos) {
34         int firstByte = 0;
35         int secondByte = 0;
36         int thirdByte = 0;
37         int fourthByte = 0;
38         int index = pos;
39         firstByte = (0x000000FF & ((int) buf[index]));
40         secondByte = (0x000000FF & ((int) buf[index + 1]));
41         thirdByte = (0x000000FF & ((int) buf[index + 2]));
42         fourthByte = (0x000000FF & ((int) buf[index + 3]));
43         index = index + 4;
44         return ((long) (firstByte << 24 | secondByte << 16 | thirdByte << 8 | fourthByte)) & 0xFFFFFFFFL;
45     }
46
47     /**
48      * 将16位的short转换成byte数组
49      *
50      * @param s
51      *            short
52      * @return byte[] 长度为2
53      * */
54     public static byte[] shortToByteArray(short s) {
55         byte[] targets = new byte[2];
56         for (int i = 0; i < 2; i++) {
57             int offset = (targets.length - 1 - i) * 8;
58             targets[i] = (byte) ((s >>> offset) & 0xff);
59         }
60         return targets;
61     }
62
63     /**
64      * 将32位整数转换成长度为4的byte数组
65      *
66      * @param s
67      *            int
68      * @return byte[]
69      * */
70     public static byte[] intToByteArray(int s) {
71         byte[] targets = new byte[2];
72         for (int i = 0; i < 4; i++) {
73             int offset = (targets.length - 1 - i) * 8;
74             targets[i] = (byte) ((s >>> offset) & 0xff);
75         }
76         return targets;
77     }
78
79     /**
80      * long to byte[]
81      *
82      * @param s
83      *            long
84      * @return byte[]
85      * */
86     public static byte[] longToByteArray(long s) {
87         byte[] targets = new byte[2];
88         for (int i = 0; i < 8; i++) {
89             int offset = (targets.length - 1 - i) * 8;
90             targets[i] = (byte) ((s >>> offset) & 0xff);
91         }
92         return targets;
93     }
94
95     /**32位int转byte[]*/
96     public static byte[] int2byte(int res) {
97         byte[] targets = new byte[4];
98         targets[0] = (byte) (res & 0xff);// 最低位
99         targets[1] = (byte) ((res >> 8) & 0xff);// 次低位
100         targets[2] = (byte) ((res >> 16) & 0xff);// 次高位
101         targets[3] = (byte) (res >>> 24);// 最高位,无符号右移。
102         return targets;
103     }
104
105     /**
106      * 将长度为2的byte数组转换为16位int
107      *
108      * @param res
109      *            byte[]
110      * @return int
111      * */
112     public static int byte2int(byte[] res) {
113         // res = InversionByte(res);
114         // 一个byte数据左移24位变成0x??000000，再右移8位变成0x00??0000
115         int targets = (res[0] & 0xff) | ((res[1] << 8) & 0xff00); // | 表示安位或
116         return targets;
117     }
118 }