1 import java.math.BigInteger;
 2 import java.security.MessageDigest;
 3 import java.security.NoSuchAlgorithmException;
 4 
 5 public class MD5Utils {
 6     /**
 7      * 使用md5的算法进行加密
 8      */
 9     public static String md5(String plainText) {
10         byte[] secretBytes = null;
11         try {
12             secretBytes = MessageDigest.getInstance("md5").digest(
13                     plainText.getBytes());
14         } catch (NoSuchAlgorithmException e) {
15             throw new RuntimeException("没有md5这个算法！");
16         }
17         String md5code = new BigInteger(1, secretBytes).toString(16);// 16进制数字
18         // 如果生成数字未满32位，需要前面补0
19         for (int i = 0; i < 32 - md5code.length(); i++) {
20             md5code = "0" + md5code;
21         }
22         return md5code;
23     }
24 
25     public static void main(String[] args) {
26         System.out.println(md5("123"));
27     }
28 
29 }