mvc与三层架构 

1.什么是mvc设计模式

M：(Model) 模型 : 应用程序的核心功能，管理这个模块中用的数据和值（bean,dao）； 

V(View )视图: 视图提供模型的展示，管理模型如何显示给用户，它是应用程序的外观（jsp/html）

2.三层架构 

 3.三层架构和MVC的区别与联系

准备工作

1.包结构

2.导入jar包

配置Tomcat 

 简化地址栏信息

工具类util：DruidUtil

package util;import com.alibaba.druid.pool.DruidDataSourceFactory;import javax.sql.DataSource;
import javax.xml.transform.Result;
import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;public class DruidUtil {private static DataSource ds;static{try {Properties ppt = new Properties();ppt.load(DruidUtil.class.getClassLoader().getResourceAsStream("druid.properties"));ds = DruidDataSourceFactory.createDataSource(ppt);} catch (Exception e) {e.printStackTrace();}}/*** 从连接池中取出一个连接给用户* @return*/public static Connection getConnection(){try {return ds.getConnection();} catch (SQLException throwables) {throwables.printStackTrace();}return null;}public static void close(Connection conn, Statement state, ResultSet rs){try {rs.close();} catch (Exception throwables) {throwables.printStackTrace();}try {state.close();} catch (Exception throwables) {throwables.printStackTrace();}try {conn.close();} catch (Exception throwables) {throwables.printStackTrace();}}
}

属性配置文件 druid.properties

url=jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8
username=root
password=123456
driverClassName=com.mysql.jdbc.Driver
initialSize=5
maxActive=10
minIdle=5
maxWait=3000

 一个请求的流程

一：MVC之Model开发

 beam包：实体类Student

package bean;
//实体类包=主要存放数据库对应的实体类
//类名=表名
//列名=属性名
//实体类包括：属性，构造方法（无参，全参），setter/getter
//属于Model(M)
public class Student {private Integer stuid;private String stuname;private Integer age;private String sex;//无参构造方法public Student() {}//全参构造方法public Student(Integer stuid, String stuname, Integer age, String sex) {this.stuid = stuid;this.stuname = stuname;this.age = age;this.sex = sex;}public Integer getStuid() {return stuid;}public void setStuid(Integer stuid) {this.stuid = stuid;}public String getStuname() {return stuname;}public void setStuname(String stuname) {this.stuname = stuname;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}@Overridepublic String toString() {return "Student{" +"stuid=" + stuid +", stuname='" + stuname + '\'' +", age=" + age +", sex='" + sex + '\'' +'}';}
}

dao包：StudentDao接口

package dao;import bean.Student;import java.util.List;//实体类名+Dao=当前类名
public interface StudentDao {//定义操作数据库的方法//查询全部方法public List<Student> getAll();
}

dao包：impl子包： StudentDaoImpl接口实现类

package dao.impl;import bean.Student;
import dao.StudentDao;
import util.DruidUtil;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
//接口名+impl=当前类名
public class StudentDaoImpl extends DruidUtil implements StudentDao {@Overridepublic List<Student> getAll() {Connection connection =null;PreparedStatement preparedStatement =null;ResultSet resultSet=null;List list=new ArrayList();try {connection = getConnection();preparedStatement = connection.prepareStatement("select * from  student");resultSet=preparedStatement.executeQuery();while (resultSet.next()){Student student = new Student();student.setStuid(resultSet.getInt("stuid"));student.setStuname(resultSet.getString("stuname"));student.setAge(resultSet.getInt("age"));student.setSex(resultSet.getString("sex"));list.add(student);}} catch (SQLException e) {e.printStackTrace();}finally {close(connection,preparedStatement,resultSet);}return list;}
}

二：MVC之Controlle开发

service包 ：StudentService接口

package service;import bean.Student;import java.util.List;//bean类名+Service=当前类名
//Service层主要定义业务逻辑，现阶段主要实现调取dao层
public interface StudentService {//查询全部方法public List<Student> getAll();
}

service包 ：impl子包：StudentServiceImpl接口实现类

package service.impl;import bean.Student;
import dao.StudentDao;
import dao.impl.StudentDaoImpl;
import service.StudentService;import java.util.List;public class StudentServiceImpl implements StudentService {private StudentDao studentDao=new StudentDaoImpl();@Overridepublic List<Student> getAll() {return studentDao.getAll();}
}

servlet包 ：StudentServlet处理类处理请求

package servlet;import bean.Student;
import service.impl.StudentServiceImpl;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;//C -controller 控制层
@WebServlet(urlPatterns = "/getstus")
public class StudentServlet extends HttpServlet {@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//接参数（接收请求参数）//写逻辑（调取service层方法）StudentServiceImpl studentService=new StudentServiceImpl();List<Student> getAll=studentService.getAll();//返结果（跳转页面）//后台传递数据给前台req.setAttribute("stulist",getAll);req.getRequestDispatcher("/show.jsp").forward(req,resp);}
}

 三：MVC之View开发

index.jsp页面  

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>$Title$</title>
</head>
<body>
<a href="getstus">查询学生列表</a>
</body>
</html>

 show.jsp页面

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body>
<h1>show.jsp</h1>
<table border="" width="500px" bgcolor="aqua"><tr><td>id</td><td>name</td><td>age</td><td>sex</td></tr><c:forEach items="${stulist}" var="stu"><tr><td>${stu.stuid}</td><td>${stu.stuname}</td><td>${stu.age}</td><td>${stu.sex==1?"男":"女"}</td></tr></c:forEach>
</table>
</body>
</html>

测试结果 

 

前后端分离技术（了解）