Add mybaits and mysql to Maven POM.xml

<dependency>
	<groupId>org.mybatis.spring.boot</groupId>
	<artifactId>mybatis-spring-boot-starter</artifactId>
	<version>2.1.1</version>
</dependency>

<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
	<scope>runtime</scope>
</dependency>
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Set the mysql address and connection information application.properties

spring.datasource.url=jdbc:mysql://localhost:3306/test? serverTimezone=UTC&useUnicode=true&characterEncoding=utf- 8 -&useSSL=false
spring.datasource.username=root
spring.datasource.password=root
#spring.datasource.type=com.alibaba.druid.pool.DruidDataSource

spring.jpa.database = MYSQL
spring.jpa.show-sql = true
spring.jpa.hibernate.ddl-auto = update

server.port=9091
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Query the database usermapper.java

import java.util.List;
import org.apache.catalina.User;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.SelectKey;
import org.apache.ibatis.annotations.Update;
import org.apache.ibatis.annotations.Results;

@Mapper
public interface UserMapper {
	 @Select("select * from user where id = #{id}")
	 List<User> getUser(int id);
}
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The service layer UserServiceImpl. Java

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;

import com.example.demo.entity.User;
import com.example.demo.mapper.UserMapper;
import org.springframework.stereotype.Service;


import com.example.demo.service.UserService;


@Service
public class UserServiceImpl implements UserService {
	@Autowired
    private UserMapper userMapper;

    @Override
    public List<User> getUser(int id) {
        returnuserMapper.getUser(id); }}Copy the code

UserService.java

import java.util.List;

import com.example.demo.entity.User;

public interface UserService {

	List<User> getUser(int id);

}
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Accept the request userController.java

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import com.example.demo.entity.User;
import com.example.demo.service.UserService;

@RestController
public class UserController {
	@Autowired
    private UserService userService;

    @RequestMapping("/getUser")
    public List<User> getUser(@RequestParam("id") int id) {
        returnuserService.getUser(id); }}Copy the code

Define the database model user.java

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name="user")
public class User {
	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	private int id;
	private String name;
	private String telephone;
	
	
	public User(a) {// A constructor is required to create a database
		
	}

    public int getId(a) {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName(a) {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getTelephone(a) {
        return telephone;
    }

    public void setTelephone(String telephone) {
        this.telephone = telephone;
    }
    @Override
    public String toString(a) {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\' ' +
                ", telephone='" + telephone + '\' ' +
                '} '; }}Copy the code

Configure boot file SpringDemoApplication. Java

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@MapperScan("com.example.demo.mapper")
public class SpringDemoApplication {

	public static void main(String[] args) { SpringApplication.run(SpringDemoApplication.class, args); }}Copy the code