利用Java自带的MD5加密

 1 package test.md5;
 2 
 3 import java.security.MessageDigest;
 4 
 5 public class MD5Util {
 6     public final static String MD5(String s) {
 7         char hexDigits[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};       
 8 
 9         try {
10             byte[] btInput = s.getBytes();
11             // 获得MD5摘要算法的 MessageDigest 对象
12             MessageDigest mdInst = MessageDigest.getInstance("MD5");
13             // 使用指定的字节更新摘要
14             mdInst.update(btInput);
15             // 获得密文
16             byte[] md = mdInst.digest();
17             // 把密文转换成十六进制的字符串形式
18             int j = md.length;
19             char str[] = new char[j * 2];
20             int k = 0;
21             for (int i = 0; i < j; i++) {
22                 byte byte0 = md[i];
23                 str[k++] = hexDigits[byte0 >>> 4 & 0xf];
24                 str[k++] = hexDigits[byte0 & 0xf];
25             }
26             return new String(str);
27         } catch (Exception e) {
28             e.printStackTrace();
29             return null;
30         }
31     }
32 
33     public static void main(String[] args) {
34         System.out.println(MD5Util.MD5("20121221"));
35         System.out.println(MD5Util.MD5("加密"));
36     }
37 }