MD5加密代码

package com.wfc.servlet;
import java.security.*;      
import java.security.spec.*;      
     
public class MD5_test {      
 public final static String MD5(String s) {      
  char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9','a', 'b', 'c', 'd', 'e', 'f' };      
  try {      
   byte[] strTemp = s.getBytes();      
   MessageDigest mdTemp = MessageDigest.getInstance("MD5");      
   mdTemp.update(strTemp);       
   byte[] md = mdTemp.digest();      
   int j = md.length;      
   char str[] = new char[j * 2];      
   int k = 0;      
   for (int i = 0; i < j; i++) {      
    byte byte0 = md[i];      
    str[k++] = hexDigits[byte0 >>> 4 & 0xf];      
    str[k++] = hexDigits[byte0 & 0xf];      
   }      
   return new String(str);      
  } catch (Exception e) {      
   return null;      
  }      
 }      
     
 /*public static void main(String[] args) {      
  // MD5_Test aa = new MD5_Test();      
  System.out.print(MD5_test.MD5("123123"));      
 }   */ 
}