md5 加密

今天弄MD5 弄了好久  找到问题：

 package com.vastis.ext.huishan;

 import java.io.UnsupportedEncodingException;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;

 public class Md5Util {
    public static String getMD5Str(String str) {
         MessageDigest messageDigest = null;

         try {
             messageDigest = MessageDigest.getInstance("MD5");

             messageDigest.reset();

             messageDigest.update(str.getBytes("UTF-8"));
         } catch (NoSuchAlgorithmException e) {
             System.out.println("NoSuchAlgorithmException caught!");
             System.exit(-1);
         } catch (UnsupportedEncodingException e) {
             e.printStackTrace();
         }

         byte[] byteArray = messageDigest.digest();

         StringBuffer md5StrBuff = new StringBuffer();

         for (int i = 0; i < byteArray.length; i++) {
             if (Integer.toHexString(0xFF & byteArray[i]).length() == 1)
                 md5StrBuff.append("0").append(Integer.toHexString(0xFF & byteArray[i]));
             else
                 md5StrBuff.append(Integer.toHexString(0xFF & byteArray[i]));
         }

         return md5StrBuff.toString();
     }


 }