JavaWeb-查询列表

1. 前端页面

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>





    
    
    
    
    
    
    
    

    
    
    
    <script src="js/jquery-2.1.0.min.js"></script>
    
    <script src="js/bootstrap.min.js"></script>
    



    
用户信息列表
    
            

        

            
编号
            
姓名
            
性别
            
年龄
            
籍贯
            
QQ
            
邮箱
            
操作
        

        

                
${s.count}
                
${user.name}
                
${user.gender}
                
${user.age}
                
${user.address}
                
${user.qq}
                
${user.email}
                
修改 删除
            

        


        

            
添加联系人
        
    

2. servlet层

package com.gaopeng.web.servlet;

import com.gaopeng.domain.User;
import com.gaopeng.service.impl.UserServiceImpl;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.util.List;

@WebServlet(name = "UserServlet", value = "/userListServlet")
public class UserServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //调用service层 完成用户表的查询操作
        UserServiceImpl userServiceimpl = new UserServiceImpl();
        List userList = userServiceimpl.getUserList();
        //将查询到的数据存入request域中
        request.setAttribute("users",userList);
        //转发到list.jsp页面
        //转发是内部跳转 不需要添加虚拟目录
        request.getRequestDispatcher("/list.jsp").forward(request,response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request,response);
    }
}

3. service层

package com.gaopeng.service.impl;

import com.gaopeng.dao.UserDao;
import com.gaopeng.dao.impl.UserDaoImpl;
import com.gaopeng.domain.User;
import com.gaopeng.service.UserService;

import java.util.List;

public class UserServiceImpl implements UserService {
    private UserDaoImpl userDao = new UserDaoImpl();
    @Override
    public List getUserList() {
        return userDao.getUserList();
    }
}

4. dao层

package com.gaopeng.dao.impl;

import com.gaopeng.dao.UserDao;
import com.gaopeng.domain.User;
import com.gaopeng.util.JDBCUtils;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

import java.util.List;

public class UserDaoImpl implements UserDao {
    private static JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
    @Override
    public List getUserList() {
        List users = jdbcTemplate.query("select * from user",new BeanPropertyRowMapper(User.class));
        return users;
    }
}

5. domain层

package com.gaopeng.domain;

import lombok.Data;

@Data
public class User {
    private int id;
    private String name;
    private String gender;
    private int age;
    private String address;
    private String qq;
    private String email;
}

6. 工具类

package com.gaopeng.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工具类 使用Durid连接池
 */
public class JDBCUtils {

    private static DataSource ds ;

    static {

        try {
            //1.加载配置文件
            Properties pro = new Properties();
            //使用ClassLoader加载配置文件，获取字节输入流
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);

            //2.初始化连接池对象
            ds = DruidDataSourceFactory.createDataSource(pro);

        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取连接池对象
     */
    public static DataSource getDataSource(){
        return ds;
    }


    /**
     * 获取连接Connection对象
     */
    public static Connection getConnection() throws SQLException {
        return  ds.getConnection();
    }
}

7. 配置文件

driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql:///day17?serverTimezone=UTC&useUnicode=true&characterEncoding=utf8
username=root
password=123456
initialSize=5
maxActive=10
maxWait=3000

8. 问题
   1. MySQL 如果是8.0的版本 需要使用com.mysql.cj.jdbc.Driver
   2. 连接数据库需要设置 时区 编码格式 jdbc:mysql:///day17?serverTimezone=UTC&useUnicode=true&characterEncoding=utf8