web登陸的邏輯與佈局實現 tomcat+html +servlet..

login.html 裏面登陸表單 提交後到servlet 裏面的loginservlet 裏面

loginservlet 中獲取數據 把數據庫封裝成bean

 request.setCharacterEncoding ("UTF-8");
String username = request.getParameter ("username");
String password = request.getParameter ("password");
//封裝user
User loginuser = new User ();
loginuser.setUsername (username);
loginuser.setPassword (password);*/

對上面的進行優化 getParamenterMap();優化後數據成爲一個map 集合 對其BeanUtils 進行封裝

    /**
         * 對上面註釋的代碼 進行簡化  優化代碼如下
         */
        //獲取所有的參數
        Map<String, String[]> map = request.getParameterMap ( );
        User loginuser = new User ();
        //用BeanUntils 進行封裝
        try {
            BeanUtils.populate (loginuser,map);
        } catch (IllegalAccessException e) {
            e.printStackTrace ( );
        } catch (InvocationTargetException e) {
            e.printStackTrace ( );
        }

在servlet 裏面調用dao下面的userdao(操作數據庫user表)

   //調用UserDao
        UserDao userDao = new UserDao ();
        User user = userDao.login (loginuser);
        if (user ==null){
            //登陸失敗
            request.getRequestDispatcher ("/failServlet").forward (request,response);
        }else {
            //登陸成功
            //存數據
            request.setAttribute ("username",loginuser);
            request.getRequestDispatcher ("/succseeServlet").forward (request,response);

        }

利用JDBCTemplate
UserDao

package com.login.Dao;

import com.login.domain.User;
import com.login.util.JDBCUTIL;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

/*
   操作數據庫的User表
* */

public class UserDao {
    /*
     聲明JDBCTemplate 對象進行共用
     */
    private JdbcTemplate Template = new JdbcTemplate (JDBCUTIL.grtDataSource());

    /**
     *登陸方法
     * @param loginUser  只有用戶名與密碼
     * @return  返回用戶的所有信息
     */
    public User login(User loginUser){
        //sql
        User user = null;
        try {
            String  sql = "select *from user where  username = ? and password = ?";
            user = Template.queryForObject (sql,
                   new BeanPropertyRowMapper<> (User.class),
                    loginUser.getUsername ( ),
                    loginUser.getPassword ( )
                                           );
            return  user;
        } catch (DataAccessException e) {
            e.printStackTrace ( );
            return  null;
        }



    }

}

在until 裏面寫工具類 比如JDBC連接類Duird連接池

package com.login.util;

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;

/**
 * JDBC 連接類  Durid連接池
 */
public class JDBCUTIL {
        private  static DataSource ds;
    static {
        //加載配置文件
            try {
                Properties properties = new Properties ();
                InputStream is = JDBCUTIL.class.getClassLoader ( ).getResourceAsStream ("druid.properties");
                properties.load (is);

                //初始化連接池
               ds =  DruidDataSourceFactory.createDataSource (properties);
            } catch (IOException e) {
                e.printStackTrace ( );
            }catch (Exception e){
                e.printStackTrace ();
            }
        }
    /*
    獲取連接池對象
    * */
    public  static  DataSource grtDataSource(){
        return ds;
    }

    /*
        獲取連接connection 對象
    */
    public static Connection getConnection() throws SQLException {

        return ds.getConnection ();
    }
}

配置文件

driverClassName=com.mysql.jdbc.Driver
url= jdbc:mysql://localhost:3306/login
username=1806253419
password=*********
initialSize=5
maxActive=10
maxWait=3000