32位MD5与16位的MD5互相转换

1. package  com.httpconnection.test;
3. import  java.security.MessageDigest ;
4. import  java.security.NoSuchAlgorithmException ;
6. public  class  Md5Test {
7.     private  static  void  Md5(String  plainText) {
8.         try  {
9.             MessageDigest  md = MessageDigest .getInstance("MD5" );
10.             md.update(plainText.getBytes());
11.             byte  b[] = md.digest();//16位的MD5
12.             int  i;
13.             System .out.println(b.length );//
14.             StringBuffer  buf = new  StringBuffer ("" );
15.             for  (int  offset = 0; offset < b.length ; offset++) {
16.                 i = b[offset];
17.                 System .out.print(i+" " );
18.                 if  (i < 0)
19.                     i += 256;
20.                 if  (i < 16)
21.                     buf.append("0" );                
22.                 buf.append(Integer .toHexString(i));
23.             }
24.             System .out.println();
25.             String  temp=buf.toString();
26.             System .out.println("result: "  +temp );// 32位的加密
27.             //以上是把字符串加密成32位的
28.             //接下来把32位的MD5转换成16位的
29.             byte  [] bb=new  byte [16];
30.             int  m=0;
31.             for (int  j=0;j<32;j+=2)
32.             {
33.                 int  num=Integer .valueOf(temp.substring(j, j+2),16);
34.                 if (num>127)
35.                 {
36.                     bb[m]=(byte ) (num-256);
37.                     System .out.print((num-256)+" " );
38.                 }
39.                 else
40.                 {
41.                     bb[m]=(byte ) (num);
42.                     System .out.print(num+" " );
43.                 }
44.                 m++;
45.             }
46.             System .out.println();
47.             String  rr=Tools.byteToLowcaseStr(bb, 0, 16);
48.             System .out.println(rr);
49.         } catch  (NoSuchAlgorithmException  e) {
50.             // TODO Auto-generated catch block
51.             e.printStackTrace();
52.         }
53.     }
54.     public  static  void  main(String  [] args)
55.     {
56.         String  pass="1zxv中国rqwe" ;
57.         Md5(pass);
58.     }
59. }