package com.loger.md5;

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

import sun.misc.BASE64Encoder;

public class Md5 {
   /**利用MD5進行加密*/
  public String EncoderByMd5(String str) throws NoSuchAlgorithmException, UnsupportedEncodingException{
    //確定計算方法
    MessageDigest md5=MessageDigest.getInstance("MD5");
    BASE64Encoder base64en = new BASE64Encoder();
    //加密后的字符串
    String newstr=base64en.encode(md5.digest(str.getBytes("utf-8")));
    return newstr;
  }
  
  /**判斷用戶密碼是否正確
   *newpasswd 用戶輸入的密碼
   *oldpasswd 正確密碼*/
  public boolean checkpassword(String newpasswd,String oldpasswd) throws NoSuchAlgorithmException, UnsupportedEncodingException{
    if(EncoderByMd5(newpasswd).equals(oldpasswd))
      return true;
    else
      return false;
  }
}

package com.loger.md5;

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

public class MyTest {
  
  public static void main(String[] args) throws NoSuchAlgorithmException, UnsupportedEncodingException {    
    Md5 md5 = new Md5();  
    String str = "apple";
    try {
      String newString = md5.EncoderByMd5(str);
      System.out.println(newString);
    } catch (NoSuchAlgorithmException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    
    System.out.println(md5.EncoderByMd5("apple").equals("HzhwvidPbEmz4xoMZyiVfw=="));
    
  }
}