2021-09-23

MVC框架的小例子`

这里主要做个保存，参考了网上的代码，不是完全原创，也不是照搬转载，自己运行修改了的！

先搭建项目环境，新建一个Spring web项目

在数据库中创建一个学生表

if exists (select * from sysdatabases where name='Test') drop database Test
--建数据库
go
create database Test
go
use Test
if exists (select * from  sysobjects where  name='students') drop table students
create table students
(
	stuId int not null primary key identity(1,1),
	stuName varchar(50) not null,
	stuAge  int not null
)

ServletAddStu.java

package controller;
import model.*;
import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/ServletAddStu")
public class ServletAddStu extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        this.doPost(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        PrintWriter out = response.getWriter();
        //设置编码格式
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        //得到姓名和年龄.封装到student类中

        String name=request.getParameter("stuName");
        int age=Integer.valueOf(request.getParameter("stuAge"));
        Student student=new Student();

        student.setStuName(name);
        student.setStuAge(age);
        //调用调价方法
        StudentDao stuDao=new StudentDao();
        stuDao.stuAdd(student);
    }

}

ServletDelete.java

package controller;
import model.*;
import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/ServletDelete")
public class ServletDelete extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        this.doPost(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        PrintWriter out = response.getWriter();
        //设置编码格式
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        //得到姓名和年龄.封装到student类中

        String name = request.getParameter("stuName");
        //调用调价方法
        StudentDao stuDao = new StudentDao();
        stuDao.stuDeletByName(name);
    }
}

Basedao.java

package model;

import java.sql.*;
public class Basedao {

    private static final String DRIVER="com.microsoft.sqlserver.jdbc.SQLServerDriver";
    private static final String URL="jdbc:sqlserver://127.0.0.1:1433;DatabaseName=Test";
    private static final String USERNAME="sa";
    private static final String PASSWORD="123456";
    private Connection conn;//连接对象
    protected PreparedStatement pst;//预编译的PreparedStatement对象
    protected ResultSet rs;//结果集resultsSet对象

    //获取数据库的连接
    public void getConnection(){
        try {
            Class.forName(DRIVER);
            conn=DriverManager.getConnection(URL,USERNAME,PASSWORD);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    //释放资源
    public void closeConnection(){
        //释放结果集
        if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        //释放预编译的对象
        if(pst!=null){
            try {
                pst.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        //释放连接
        if(conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }

    //增删改
    public int executeUpdate(String sql,String []paras){
        int count=0;
        try {
            this.getConnection();//连接数据库
            pst=conn.prepareStatement(sql);//基于sql语句创建预编译对象
            //如果paras不为空或者长度大于0 就赋值
            if(paras!=null && paras.length>0){
                for (int i = 0; i < paras.length; i++) {
                    pst.setString(i+1, paras[i]);
                }
            }
            count=pst.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            closeConnection();
        }
        return count;
    }


    //查询
    public ResultSet executeQuery(String sql,String[]paras){
        try {
            this.getConnection();//连接数据库
            pst=conn.prepareStatement(sql);//基于sql语句创建预编译对象
            //如果paras不为空或者长度大于0 就赋值
            if(paras!=null && paras.length>0){
                int index=1;
                for (String para : paras) {
                    pst.setString(index,para);

                    index++;
                }
            }
            rs=pst.executeQuery();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }


}

上面的查询方法没有用到，但保留着以后可以扩充查询功能
Student.java

package model;

public class Student {
    private int stuId;//编号
    private String stuName;//姓名
    private int stuAge;//年龄
    public int getStuId() {
        return stuId;
    }
    public void setStuId(int stuId) {
        this.stuId = stuId;
    }
    public String getStuName() {
        return stuName;
    }
    public void setStuName(String stuName) {
        this.stuName = stuName;
    }
    public int getStuAge() {
        return stuAge;
    }
    public void setStuAge(int stuAge) {
        this.stuAge = stuAge;
    }


}

StudentDao.java

package model;

public class StudentDao extends Basedao{
    public int stuAdd(Student stu) {
        int count=0;
        String sql="insert into students values (?,?)";
        String [] paras={stu.getStuName(),String.valueOf(stu.getStuAge())};
        count=super.executeUpdate(sql, paras);
        return count;
    }
    public int stuDeletByName(String name)
    {
        int c=0;
        String sql="delete from students where stuName =? ";
        String [] paras={name};
        c=super.executeUpdate(sql, paras);
        return c;
    }
}

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>欢迎</title>
  </head>
  <body>
  登入成功！<br>
  <a href="Add.jsp">添加用户</a><br>
  <a href="Show.jsp">删除用户</a>
  </body>
</html>

Add.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%
    String path = request.getContextPath();
    String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
    <base href="<%=basePath%>">

    <title>添加</title>

    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
    <script type="text/javascript" src="<%=path %>/js/jquery-3.3.1.min.js"></script>
    <script type="text/javascript">
        function onSubmit(){
            var name=$("#stuName").val();
            if(name=="") {
                alert("姓名不能为空");
                return false;  // 返回false，不跳转
            }else {
                return true;   // 返回true，跳转
            }

        }
    </script>
    <title>警告</title>

</head>

<body>
注册添加 <br>
<form action="/ServletAddStu" method="post">

    <p>姓名：<input type="text" name="stuName" id="stuName"/></p>
    <p>年龄:
        <select name="stuAge">
            <option value="18">18</option>
            <option value="19">19</option>
            <option value="20">20</option>
            <option value="21">21</option>
            <option value="22">22</option>
        </select>
    </p>
    <p><input type="submit" value="提交" onClick="return onSubmit()"></p>
</form>

</body>
</html>

Show.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%
    String path = request.getContextPath();
    String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
    <base href="<%=basePath%>">
    <title>删除用户</title>
    <script type="text/javascript" src="<%=path %>/js/jquery-3.3.1.min.js"></script>
    <script type="text/javascript">
        function onSubmit(){
            var name=$("#stuName").val();
            if(name=="") {
                alert("姓名不能为空");
                return false;  // 返回false，不跳转
            }else {
                return true;   // 返回true，跳转
            }

        }
    </script>
    <title>警告</title>
</head>
<body>
<form action="/ServletDelete" method="post">

    <p>姓名：<input type="text" name="stuName" id="stuName"/></p>
    <p><input type="submit" value="提交" onClick="return onSubmit()"></p>
</form>
</body>
</html>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/applicationContext.xml</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>*.form</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>ServletAddStu</servlet-name>
        <servlet-class>controller.ServletAddStu</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>ServletAddStu</servlet-name>
        <!-- 监听所有请求 -->
        <url-pattern>/controller.ServletAddStu</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>ServletDelete</servlet-name>
        <servlet-class>controller.ServletDelete</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>ServletDelete</servlet-name>
        <!-- 监听所有请求 -->
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

*实验结果

参考代码：
https://blog.youkuaiyun.com/miaomiaowyj/article/details/79779475