package com.louis.utils;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Utils {
    /**
     * 使用md5加密
     */
    public static String md5(String plainText) {
        byte[] secretBytes = null;
        try
 
 {
            //普通的字符串轉化成數組
            secretBytes = MessageDigest.getInstance("md5").digest(
                    plainText.getBytes());
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("找不到md5實例");
        }
        String md5code = new BigInteger(1, secretBytes).toString(16);
        
        
 
for (int i = 0; i < 32 - md5code.length(); i++) {
            md5code = "0" + md5code;
        }
        return md5code;
    }
/*    //和數據庫的加密一樣，同一個字符串通過md5加密，結果是一樣的
    public static void main(String[] args) {
        System.out.println(md5("123"));
    }*/
}

package com.louis.web.servlet;

 
import java.io.IOException;
import java.util.Date;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.beanutils.ConvertUtils;

import com.louis.domain.User;
import com.louis.myconvertor.MyConverter;
import com.louis.service.UserService;
import com.louis.service.impl.UserServiceImpl;
import com.louis.utils.MD5Utils;
import com.louis.utils.UUIDUtils;

/**
 * 和用戶相關的servlet
 */

public class UserServlet extends BaseServlet {
    
    
    public String add(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("userServlet的add方法執行了");
        return null;
    }
    //調轉到註冊頁面
    public String registUI(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        return "/jsp/register.jsp";
    }
    
    //完成註冊
    public String regist(HttpServletRequest request,HttpServletResponse response) throws Exception {
        //1封裝數據
        User user = new User();
        
        //註冊自定義轉化器
        ConvertUtils.register(new MyConverter(), Date.class);
        
        BeanUtils.populate(user, request.getParameterMap());
        
        //1.1設置用戶id
        user.setUid(UUIDUtils.getId());
        
        //1.2設置激活碼
        user.setCode(UUIDUtils.getCode());
        
        //1.3加密密碼
        user.setPassword(MD5Utils.md5(user.getPassword()));
        
        //2調用service完成註冊
        UserService service = new UserServiceImpl();
        service.regist(user);
        
        
        //頁面請求轉發
        request.setAttribute("msg", "用戶已註冊，請去郵箱激活");
        return "/jsp/msg.jsp";
    }

}

(五)密碼加密