Spring Boot（三）整合Mybatis

1、准备好数据库

create database bootmybatis;

use bootmybatis;

create table `user` (
	`id` int auto_increment,
    `name` varchar(20),
    primary key(`id`)
) default charset=utf8mb4;

insert into user values(1, 'u1');
insert into user values(2, 'u2');

select * from user;

2、创建新工程并编辑pom文件

<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.github.ralgond</groupId>
	<artifactId>boot-mybatis</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.3.0.RELEASE</version>
	</parent>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-jdbc</artifactId>
		</dependency>
		<!-- https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter -->
		<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter</artifactId>
			<version>2.1.3</version>
		</dependency>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<scope>runtime</scope>
		</dependency>
	</dependencies>

	<properties>
		<start-class>com.github.ralgond.bootmybatis.BootMybatisMainApp</start-class>
	</properties>

	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.0</version>
				<configuration>
					<source>1.8</source>
					<target>1.8</target>
				</configuration>
			</plugin>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>

		<resources>
			<resource>
				<directory>src/main/java</directory>
				<includes>
					<include>**/*.xml</include>
				</includes>
			</resource>
			<resource>
				<directory>src/main/resources</directory>
				<includes>
					<include>**/*.*</include>
				</includes>
			</resource>
		</resources>
	</build>
</project>

3、编辑src/main/resources/application.yml文件

server:
  port: 8888
  
spring:
  datasource:
    username: root
    password: root
    url: jdbc:mysql://localhost:3306/bootmybatis?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
    driver-class-name: com.mysql.cj.jdbc.Driver

mybatis:
  mapper-locations: classpath:mapping/*Mapper.xml
  type-aliases-package: com.github.ralgond.bootmybatis.entity

4、各个文件的位置，如下图

5、编辑主启动类

package com.github.ralgond.bootmybatis;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.github.ralgond.bootmybatis.entity.User;

@MapperScan("com.github.ralgond.bootmybatis")
@SpringBootApplication
@RestController
public class BootMybatisMainApp {
	
	@Autowired
	UserService userService;
	
	@RequestMapping(method=RequestMethod.GET, value="/user/{id}")
	public User hello(@PathVariable("id") Integer id) {
		return userService.get(id);
	}
	
	public static void main(String args[]) {
		SpringApplication.run(BootMybatisMainApp.class, args);
	}
}

6、编辑User类

package com.github.ralgond.bootmybatis.entity;

public class User {
	private Integer id;
        private String name;
    
	public User() {
	}
	public User(Integer id, String name) {
		this.id = id;
		this.name = name;
	}
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	@Override
	public String toString() {
		return "User [id=" + id + ", name=" + name + "]";
	}
}

7、编辑UserMapper接口

package com.github.ralgond.bootmybatis;

import org.springframework.stereotype.Repository;

import com.github.ralgond.bootmybatis.entity.User;

@Repository
public interface UserMapper {
	public User get(int id);
}

8、编辑UserMapper.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.github.ralgond.bootmybatis.UserMapper">
 
    <resultMap id="BaseResultMap" type="User">
        <result column="id" jdbcType="INTEGER" property="id" />
        <result column="name" jdbcType="VARCHAR" property="name" />
    </resultMap>
 
    <select id="get" resultType="User">
        select * from user where id = #{id}
    </select>
 
</mapper>

9、编辑UserService类

package com.github.ralgond.bootmybatis;

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

import com.github.ralgond.bootmybatis.entity.User;

@Service
public class UserService {
	
	@Autowired
	UserMapper userMapper;
	
	public User get(int id) {
		return userMapper.get(id);
	}
}

10、启动运行

在浏览器输入http://localhost:8888/user/1，便可看到结果：