java整型数与网络字节序的 byte[] 数组转换关系

学习笔记，转自百度文库。

工作项目需要在java和c/c++之间进行socket通信，socket通信是以字节流或者字节包进行的，socket发送方须将数据转换为字节流或者字节包，而接收方则将字节流和字节包再转换回相应的数据类型。如果发送方和接收方都是同种语言，则一般只涉及到字节序的调整。而对于java和c/c++的通信，则情况就要复杂一些，主要是因为java中没有unsigned类型，并且java和c在某些数据类型上的长度不一致。
    本文就是针对这种情况，整理了java数据类型和网络字节流或字节包(相当于java的byte数组)之间转换方法。实际上网上这方面的资料不少，但往往不全，甚至有些有错误，于是就花了点时间对java整型数和网络字节序的byte[]之间转换的各种情况做了一些验证和整理。整理出来的函数如下：

  1 public class ByteConvert {
  2     // 以下 是整型数 和 网络字节序的  byte[] 数组之间的转换
  3     public static byte[] longToBytes(long n) {
  4         byte[] b = new byte[8];
  5         b[7] = (byte) (n & 0xff);
  6         b[6] = (byte) (n >> 8  & 0xff);
  7         b[5] = (byte) (n >> 16 & 0xff);
  8         b[4] = (byte) (n >> 24 & 0xff);
  9         b[3] = (byte) (n >> 32 & 0xff);
 10         b[2] = (byte) (n >> 40 & 0xff);
 11         b[1] = (byte) (n >> 48 & 0xff);
 12         b[0] = (byte) (n >> 56 & 0xff);
 13         return b;
 14     }
 15     
 16     public static void longToBytes( long n, byte[] array, int offset ){
 17         array[7+offset] = (byte) (n & 0xff);
 18         array[6+offset] = (byte) (n >> 8 & 0xff);
 19         array[5+offset] = (byte) (n >> 16 & 0xff);
 20         array[4+offset] = (byte) (n >> 24 & 0xff);
 21         array[3+offset] = (byte) (n >> 32 & 0xff);
 22         array[2+offset] = (byte) (n >> 40 & 0xff);
 23         array[1+offset] = (byte) (n >> 48 & 0xff);
 24         array[0+offset] = (byte) (n >> 56 & 0xff);
 25     }
 26     
 27     public static long bytesToLong( byte[] array )
 28     {
 29         return ((((long) array[ 0] & 0xff) << 56)
 30               | (((long) array[ 1] & 0xff) << 48)
 31               | (((long) array[ 2] & 0xff) << 40)
 32               | (((long) array[ 3] & 0xff) << 32)
 33               | (((long) array[ 4] & 0xff) << 24)
 34               | (((long) array[ 5] & 0xff) << 16)
 35               | (((long) array[ 6] & 0xff) << 8) 
 36               | (((long) array[ 7] & 0xff) << 0));        
 37     }
 38     
 39     public static long bytesToLong( byte[] array, int offset )
 40     {
 41         return ((((long) array[offset + 0] & 0xff) << 56)
 42               | (((long) array[offset + 1] & 0xff) << 48)
 43               | (((long) array[offset + 2] & 0xff) << 40)
 44               | (((long) array[offset + 3] & 0xff) << 32)
 45               | (((long) array[offset + 4] & 0xff) << 24)
 46               | (((long) array[offset + 5] & 0xff) << 16)
 47               | (((long) array[offset + 6] & 0xff) << 8) 
 48               | (((long) array[offset + 7] & 0xff) << 0));            
 49     }
 50     
 51     public static byte[] intToBytes(int n) {
 52         byte[] b = new byte[4];
 53         b[3] = (byte) (n & 0xff);
 54         b[2] = (byte) (n >> 8 & 0xff);
 55         b[1] = (byte) (n >> 16 & 0xff);
 56         b[0] = (byte) (n >> 24 & 0xff);
 57         return b;
 58     }
 59     
 60     public static void intToBytes( int n, byte[] array, int offset ){
 61         array[3+offset] = (byte) (n & 0xff);
 62         array[2+offset] = (byte) (n >> 8 & 0xff);
 63         array[1+offset] = (byte) (n >> 16 & 0xff);
 64         array[offset] = (byte) (n >> 24 & 0xff);
 65     }    
 66 
 67     public static int bytesToInt(byte b[]) {
 68         return    b[3] & 0xff 
 69                | (b[2] & 0xff) << 8 
 70                | (b[1] & 0xff) << 16
 71                | (b[0] & 0xff) << 24;
 72     }
 73 
 74     public static int bytesToInt(byte b[], int offset) {
 75         return    b[offset+3] & 0xff 
 76                | (b[offset+2] & 0xff) << 8 
 77                | (b[offset+1] & 0xff) << 16
 78                | (b[offset] & 0xff) << 24;
 79     }
 80 
 81     public static byte[] uintToBytes( long n )
 82     {
 83         byte[] b = new byte[4];
 84         b[3] = (byte) (n & 0xff);
 85         b[2] = (byte) (n >> 8 & 0xff);
 86         b[1] = (byte) (n >> 16 & 0xff);
 87         b[0] = (byte) (n >> 24 & 0xff);
 88         
 89         return b;
 90     }
 91 
 92     public static void uintToBytes( long n, byte[] array, int offset ){
 93         array[3+offset] = (byte) (n );
 94         array[2+offset] = (byte) (n >> 8 & 0xff);
 95         array[1+offset] = (byte) (n >> 16 & 0xff);
 96         array[offset]   = (byte) (n >> 24 & 0xff);
 97     }
 98 
 99     public static long bytesToUint(byte[] array) {  
100         return ((long) (array[3] & 0xff))  
101              | ((long) (array[2] & 0xff)) << 8  
102              | ((long) (array[1] & 0xff)) << 16  
103              | ((long) (array[0] & 0xff)) << 24;  
104     }
105 
106     public static long bytesToUint(byte[] array, int offset) {   
107         return ((long) (array[offset+3] & 0xff))  
108               | ((long) (array[offset+2] & 0xff)) << 8  
109              | ((long) (array[offset+1] & 0xff)) << 16  
110              | ((long) (array[offset]   & 0xff)) << 24;  
111     }
112 
113     public static byte[] shortToBytes(short n) {
114         byte[] b = new byte[2];
115         b[1] = (byte) ( n       & 0xff);
116         b[0] = (byte) ((n >> 8) & 0xff);
117         return b;
118     }
119     
120     public static void shortToBytes(short n, byte[] array, int offset ) {        
121         array[offset+1] = (byte) ( n       & 0xff);
122         array[offset] = (byte) ((n >> 8) & 0xff);
123     }
124     
125     public static short bytesToShort(byte[] b){
126         return (short)( b[1] & 0xff
127                       |(b[0] & 0xff) << 8 ); 
128     }    
129 
130     public static short bytesToShort(byte[] b, int offset){
131         return (short)( b[offset+1] & 0xff
132                       |(b[offset]    & 0xff) << 8 ); 
133     }
134 
135     public static byte[] ushortToBytes(int n) {
136         byte[] b = new byte[2];
137         b[1] = (byte) ( n       & 0xff);
138         b[0] = (byte) ((n >> 8) & 0xff);
139         return b;
140     }    
141 
142     public static void ushortToBytes(int n, byte[] array, int offset ) {
143         array[offset+1] = (byte) ( n       & 0xff);
144         array[offset] = (byte)   ((n >> 8) & 0xff);
145     }
146 
147     public static int bytesToUshort(byte b[]) {
148         return    b[1] & 0xff 
149                | (b[0] & 0xff) << 8;
150     }    
151 
152     public static int bytesToUshort(byte b[], int offset) {
153         return    b[offset+1] & 0xff 
154                | (b[offset]   & 0xff) << 8;
155     }    
156 
157     public static byte[] ubyteToBytes( int n ){
158         byte[] b = new byte[1];
159         b[0] = (byte) (n & 0xff);
160         return b;
161     }
162 
163     public static void ubyteToBytes( int n, byte[] array, int offset ){
164         array[0] = (byte) (n & 0xff);
165     }
166 
167     public static int bytesToUbyte( byte[] array ){            
168         return array[0] & 0xff;
169     }        
170 
171     public static int bytesToUbyte( byte[] array, int offset ){            
172         return array[offset] & 0xff;
173     }    
174     // char 类型、 float、double 类型和 byte[] 数组之间的转换关系还需继续研究实现。 
175 }
176 
177 
178 测试程序如下：
179 
180 public class ByteConvertTest {
181     
182     public static String byte2Hex(byte[] buf) 
183     {
184         StringBuffer strbuf = new StringBuffer();
185         strbuf.append("{");
186         for (byte b : buf) 
187         {
188             if (b == 0) 
189             {
190                 strbuf.append("00");
191             } 
192             else if (b == -1) 
193             {
194                 strbuf.append("FF");
195             } 
196             else 
197             {
198                 String str = Integer.toHexString(b).toUpperCase();
199                 // sb.append(a);
200                 if (str.length() == 8) 
201                 {
202                     str = str.substring(6, 8);
203                 } 
204                 else if (str.length() < 2) 
205                 {
206                     str = "0" + str;
207                 }
208                 strbuf.append(str);
209             }
210             strbuf.append(" ");
211         }
212         strbuf.append("}");
213         return strbuf.toString();
214     }    
215 
216     public static byte[] longToBytes(long n) {
217         byte[] b = new byte[8];
218         b[7] = (byte) (n & 0xff);
219         b[6] = (byte) (n >> 8  & 0xff);
220         b[5] = (byte) (n >> 16 & 0xff);
221         b[4] = (byte) (n >> 24 & 0xff);
222         b[3] = (byte) (n >> 32 & 0xff);
223         b[2] = (byte) (n >> 40 & 0xff);
224         b[1] = (byte) (n >> 48 & 0xff);
225         b[0] = (byte) (n >> 56 & 0xff);
226         return b;
227     }
228 
229     public static long bytesToLong( byte[] array )
230     {
231         return ((((long) array[ 0] & 0xff) << 56)
232               | (((long) array[ 1] & 0xff) << 48)
233               | (((long) array[ 2] & 0xff) << 40)
234               | (((long) array[ 3] & 0xff) << 32)
235               | (((long) array[ 4] & 0xff) << 24)
236               | (((long) array[ 5] & 0xff) << 16)
237               | (((long) array[ 6] & 0xff) << 8) 
238               | (((long) array[ 7] & 0xff) ));        
239     }
240     
241     public static int bytesToInt(byte b[]) {
242         return    b[3] & 0xff 
243                | (b[2] & 0xff) << 8 
244                | (b[1] & 0xff) << 16
245                | (b[0] & 0xff) << 24;
246     }
247 
248     public static long bytesToUint(byte[] array) {  
249         return ((long) (array[3] & 0xff))  
250              | ((long) (array[2] & 0xff)) << 8  
251              | ((long) (array[1] & 0xff)) << 16  
252              | ((long) (array[0] & 0xff)) << 24;  
253     }
254 
255     public static byte[] uintToBytes( long n )
256     {
257         byte[] b = new byte[4];
258         b[3] = (byte) (n & 0xff);
259         b[2] = (byte) (n >> 8 & 0xff);
260         b[1] = (byte) (n >> 16 & 0xff);
261         b[0] = (byte) (n >> 24 & 0xff);
262         
263         return b;
264     }
265     
266 
267     public static byte[] shortToBytes(short n) {
268         byte[] b = new byte[2];
269         b[1] = (byte) ( n       & 0xff);
270         b[0] = (byte) ((n >> 8) & 0xff);
271         return b;
272     }
273     
274     public static short bytesToShort(byte[] b){
275         return (short)( b[1] & 0xff
276                       |(b[0] & 0xff) << 8 ); 
277     }
278     
279     static void testShortConvert(){
280         System.out.println("=================== short convert =============");
281         System.out.println("byte2Hex(shortToBytes((short)0x11f2))"+byte2Hex(shortToBytes((short)0x11f2)));        
282         System.out.print("println 0x11f2:");
283         System.out.println((short)0x11f2);        
284         System.out.println("byte2Hex(shortToBytes((short)0xf1f2))"+byte2Hex(shortToBytes((short)0xf1f2)));        
285         System.out.print("println 0xf1f2:");
286         System.out.println((short)0xf1f2);            
287         System.out.print("println bytesToShort(shortToBytes((short)0x11f2)):");
288         System.out.println((short)bytesToShort(shortToBytes((short)0x11f2)));            
289         System.out.print("println bytesToShort(shortToBytes((short)0xf1f2)):");
290         System.out.println((short)bytesToShort(shortToBytes((short)0xf1f2)));        
291     }
292     
293 
294     public static byte[] ushortToBytes(int n) {
295         byte[] b = new byte[2];
296         b[1] = (byte) (n & 0xff);
297         b[0] = (byte) (n >> 8 & 0xff);
298         return b;
299     }
300     
301 
302     public static int bytesToUshort(byte b[]) {
303         return    b[1] & 0xff 
304                | (b[0] & 0xff) << 8;
305     }
306 
307     static void testUshortConvert(){
308         System.out.println("=================== Ushort convert =============");
309         System.out.println("byte2Hex(ushortToBytes(0x11f2))"+byte2Hex(ushortToBytes(0x11f2)));        
310         System.out.print("println 0x11f2:");
311         System.out.println(0x11f2);        
312         System.out.println("byte2Hex(ushortToBytes(0xf1f2))"+byte2Hex(ushortToBytes(0xf1f2)));        
313         System.out.print("println 0xf1f2:");
314         System.out.println(0xf1f2);            
315         System.out.print("println bytesToUshort(ushortToBytes(0x11f2)):");
316         System.out.println(bytesToUshort(ushortToBytes(0x11f2)));            
317         System.out.print("println bytesToUshort(ushortToBytes(0xf1f2)):");
318         System.out.println(bytesToUshort(ushortToBytes(0xf1f2)));        
319     }
320     
321     public static byte[] ubyteToBytes( int n ){
322         byte[] b = new byte[1];
323         b[0] = (byte) (n & 0xff);
324         return b;
325     }
326 
327     public static int bytesToUbyte( byte[] array ){            
328         return array[0] & 0xff;
329     }    
330 
331     static void testUbyteConvert(){
332         System.out.println("=================== Ubyte convert =============");
333         System.out.println("byte2Hex(ubyteToBytes(0x1112))"+byte2Hex(ubyteToBytes(0x1112)));        
334         System.out.print("println 0x1112:");
335         System.out.println(0x1112);        
336         System.out.println("byte2Hex(ubyteToBytes(0xf2))"+byte2Hex(ubyteToBytes(0xf2)));        
337         System.out.print("println 0xf2:");
338         System.out.println(0xf2);            
339         System.out.print("println bytesToUbyte(ubyteToBytes(0x1112)):");
340         System.out.println(bytesToUbyte(ubyteToBytes(0x1112)));            
341         System.out.print("println bytesToUbyte(ubyteToBytes(0xf1f2)):");
342         System.out.println(bytesToUbyte(ubyteToBytes(0xf1f2)));        
343     }
344     
345     
346     /**
347      * @param args
348      */
349     public static void main(String[] args) {
350         // TODO Auto-generated method stub        
351         byte[] array = new byte[4];
352         array[3] = (byte) 0xF4;
353         array[2] = 0x13;
354         array[1] = 0x12;
355         array[0] = 0x11;
356         
357         System.out.println("=================== Integer bytes =============");
358         
359         System.out.println("the bytes is:"+byte2Hex(array) );
360         System.out.print("println bytesToInt :");
361         System.out.println( bytesToInt(array));
362         System.out.printf("printf bytesToInt :%X
", bytesToInt(array));
363         
364         System.out.println("=================== long bytes =============");
365         byte[] longBytes = new byte[8];
366         
367         longBytes[7] = (byte) 0xf7;
368         longBytes[6] = (byte) 0x16;
369         longBytes[5] = (byte) 0xf5;
370         longBytes[4] = (byte) 0x14;
371         longBytes[3] = (byte) 0xf3;
372         longBytes[2] = (byte) 0x12;
373         longBytes[1] = (byte) 0xf1;
374         longBytes[0] = (byte) 0x10;
375         
376 
377         System.out.println( "the bytes is:"+byte2Hex(longBytes) );
378         System.out.printf("printf bytesToLong:%X
",bytesToLong(longBytes));
379         
380         System.out.println("=================byte to long ================");
381         
382         byte b = (byte)0xf1;
383         System.out.print("Println the byte:");
384         System.out.println(b);
385         System.out.printf("Printf the byte:%X
",b);
386         long l = b;
387         System.out.print("Println byte to long:");
388         System.out.println(l);
389         System.out.printf("printf byte to long:%X
",l);
390         
391         System.out.println("================= uint Bytes ================");
392         
393         byte[] uint = new byte[4];
394         uint[3] = (byte) 0xf3;
395         uint[2] = (byte) 0x12;
396         uint[1] = (byte) 0xf1;
397         uint[0] = (byte) 0xFF;
398         
399         System.out.println( "the bytes is:"+byte2Hex(uint) );
400         System.out.printf("printf bytesToUint:%X
",bytesToUint(uint));
401         System.out.print("Println bytesToUint:");
402         System.out.println(bytesToUint(uint));
403         System.out.println("byte2Hex(uintToBytes(0x11f2f3f4f5f6f7f8l)):"+byte2Hex(uintToBytes(0x11f2f3f4f5f6f7f8l)));
404         
405         System.out.println("===============Long Integer==============");        
406         System.out.print("println 0x11f2f3f4f5f6f7f8l:");
407         System.out.println(0x11f2f3f4f5f6f7f8l);        
408         System.out.printf("Printf 0x11f2f3f4f5f6f7f8l:%X
",0x11f2f3f4f5f6f7f8l);
409         System.out.println("println byte2Hex(longToBytes(0x11f2f3f4f5f6f7f8l))"+byte2Hex(longToBytes(0x11f2f3f4f5f6f7f8l)));
410         // 注意，下面的这行，并不能获得正确的uint。
411         System.out.printf("printf bytesToUint(longToBytes(0x11f2f3f4f5f6f7f8l):%X
",bytesToUint(longToBytes(0x11f2f3f4f5f6f7f8l)));
412         
413         System.out.println("===============bytesToLong(longToBytes())==============");
414         System.out.println(bytesToLong(longToBytes(0x11f2f3f4f5f6f7f8l)));
415         System.out.printf("%X
",bytesToLong(longToBytes(0x11f2f3f4f5f6f7f8l)));
416         
417         testShortConvert();
418         testUshortConvert();
419         testUbyteConvert();
420     }
421 
422 }
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原文地址：https://www.cnblogs.com/ning1121/p/3481048.html