Spring mvc是如何实现与数据库的前后端的连接操作的?

package cn.tedu;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

//启动类

@SpringBootApplication

public class RunApp {

     public static void main(String[] args) {

         SpringApplication.run(RunApp. class );

     }

}

package cn.tedu.pojo;

//Model用来封装数据

public class Car {

     private int id;

     private String name;

     private double price;

     //Constructor构造方法，用来方便的new

     public Car(){}

     public Car( int id, String name, double price) {

         this .id = id;

         this .name = name;

         this .price = price;

     }

     public int getId() {

         return id;

     }

     public void setId( int id) {

         this .id = id;

     }

     public String getName() {

         return name;

     }

     public void setName(String name) {

         this .name = name;

     }

     public double getPrice() {

         return price;

     }

     public void setPrice( double price) {

         this .price = price;

     }

}

package cn.tedu.controller;

//MVC里的C层，用来接受请求和做出响应(springmvc)

import cn.tedu.pojo.Car;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RestController;

@RestController //接受请求，并把json数据返回

@RequestMapping ( "car" )  //规定了url地址的写法

public class CarController {

//方式一值会在网页中出现

     @RequestMapping ( "get" )

     public Car get(){

         Car c = new Car( 10 , "BMW" , 19.9 );   //出发钩造函数,此处触发的是含参构造;

         return c ;

     }

//方式二值会在网页中出现

  @RequestMapping ( "save3" )

     public Car save() {

         car.setAge( 213 );

         car.setSex( "男" );

         car.setId( 32 );

          car.setPrice( 32 );

         return car;

     }

方式三这种方式的值会在idea中打印不会再网页中出现

@RequestMapping ( "save3" )

     public Car save() {

         car.setAge( 213 );

         car.setSex( "男" );

         car.setId( 32 );

          car.setPrice( 32 );

         System.out.println(car);

}

package cn.tedu.controller;

import cn.tedu.pojo.Car;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RestController;

import javax.naming.Name;

import java.net.URL;

import java.util.HashMap;

import java.util.Map;

//这是一个c层用来接收请求和做出响应

@RestController

//@RequestMapping("car")//规定了url的写法此时的值可以任意写

public class Controller {

    @RequestMapping ( "replace" )

     public String replace(){

        // System.out.println(id+name+age);

         return "hkjds" ;

     }

//方式二值会在网页中出现

  @RequestMapping ( "save3" )

     public Car save() {

         car.setAge( 213 );

         car.setSex( "男" );

         car.setId( 32 );

          car.setPrice( 32 );

         return car;

     }

}

}

package cn.tedu.controller;

import cn.tedu.pojo.Car;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RestController;

import javax.naming.Name;

import java.net.URL;

import java.util.HashMap;

import java.util.Map;

//这是一个c层用来接收请求和做出响应

@RestController

//@RequestMapping("car")//规定了url的写法此时的值可以任意写

public class Controller {

  @RequestMapping ( "get2" )

     public void get(Integer id,String name){ //此处使用int类型必须赋值  引用类型不用必须赋值最好使用引用类型

         System.out.println(id+name);

     }

     @RequestMapping ( "get" )

                public void get(Integer id){ //此处使用int类型必须赋值  引用类型不用必须赋值

         System.out.println(id);

        }

package cn.tedu.controller;

import cn.tedu.pojo.Car;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RestController;

@RestController

@RequestMapping ( "car3" )

//使用restful风格

public class CarController {

    @RequestMapping ( "get2/{sex}/{id}/{name}" ) //此地方的参数顺序必须和下面以及地址值都必须一样

public void   get2( @PathVariable String sex,

                  @PathVariable Integer id,

                  @PathVariable String name){

        System.out.println( "数据插入成功" +sex+name+id);

       // System.out.println("数据插入成功"+name+id);

     }

}

package cn.tedu.controller;

import cn.tedu.pojo.Car;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RestController;

import javax.naming.Name;

import java.net.URL;

import java.util.HashMap;

import java.util.Map;

//这是一个c层用来接收请求和做出响应

@RestController

//@RequestMapping("car")//规定了url的写法此时的值可以任意写

public class Controller {

     //使用框架接收网站参数

     @RequestMapping ( "get3" )

    public void   get3(Car car){

        System.out.println(car.getSex()+car.getName()+car.getId());

    }

}

package cn.tedu.controller;

import cn.tedu.pojo.Car;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RestController;

import org.yaml.snakeyaml.events.Event;

import javax.naming.Name;

import java.sql.*;

import java.util.Scanner;

@RestController

@RequestMapping ( "user" )

public class UserContoller {

     @RequestMapping ( "save" )

    public void save(Integer id,String name,Integer age) throws Exception {

         System.out.println(id+name+age);

         Class.forName( "com.mysql.jdbc.Driver" );

         //获取连接

         String url = "jdbc:mysql:///cgb2104?characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai" ;

         Connection conn = DriverManager.getConnection(url, "root" , "root" );

         //获取传输器

//        String sql= "insert into user(id,name) values(?,?)";//给指定的字段设置值

         String sql= "insert into user values(?,?,?)" ; //所有字段设置值

         PreparedStatement ps = conn.prepareStatement(sql);

         //给SQL设置参数

         ps.setInt( 1 ,id); //给第一个？设置值

         ps.setString( 2 ,name); //给第二个？设置值

         ps.setInt( 3 ,age); //给第三个？设置值

         //执行SQL

         int rows = ps.executeUpdate();

         //释放资源 -- OOM(OutOfMemory)

         ps.close();

         conn.close();

     }