文章轉載自http://blog.csdn.net/leetcworks/article/details/7390731
1 package com.util;
2
3 /**
4 *
5 * <ul>
6 * <li>文件名稱: com.born.util.ByteUtil.java</li>
7 * <li>文件描述: byte轉換工具</li>
8 * <li>版權所有: 版權所有(C)2001-2006</li>
9 * <li>公 司: bran</li>
10 * <li>內容摘要:</li>
11 * <li>其他說明:</li>
12 * <li>完成日期：2011-7-18</li>
13 * <li>修改記錄0：無</li>
14 * </ul>
15 *
16 * @version 1.0
17 * @author 許力多
18 */
19 public class ByteUtil {
20 /**
21 * 轉換short為byte
22 *
23 * @param b
24 * @param s
25 * 需要轉換的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 * 通過byte數組取到short
35 *
36 * @param b
37 * @param index
38 * 第幾位開始取
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 * 轉換int為byte數組
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 * 通過byte數組取到int
61 *
62 * @param bb
63 * @param index
64 * 第幾位開始
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 * 轉換long型為byte數組
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 * 通過byte數組取到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 * 字符到字節轉換
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(); // 將最高位保存在最低位
119 temp = temp >> 8; // 向右移8位
120 }
121 }
122
123 /**
124 * 字節到字符轉換
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轉換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 * 通過byte數組取得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轉換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 * 通過byte數組取得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 * 將一個單字節的byte轉換成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 * 將一個單字節的Byte轉換成十六進制的數
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 * 將一個4byte的數組轉換成32位的int
27 *
28 * @param buf
29 * bytes buffer
30 * @param byte[]中開始轉換的位置
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 * 將16位的short轉換成byte數組
49 *
50 * @param s
51 * short
52 * @return byte[] 長度為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 * 將32位整數轉換成長度為4的byte數組
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轉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,無符號右移。
102 return targets;
103 }
104
105 /**
106 * 將長度為2的byte數組轉換為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 // 一個byte數據左移24位變成0x??000000，再右移8位變成0x00??0000
115 int targets = (res[0] & 0xff) | ((res[1] << 8) & 0xff00); // | 表示安位或
116 return targets;
117 }
118 }
