基于xml文件配置

1、修改pom文件

添加MySQL依赖和mybatis-spring-boot-starter模块

 <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.26</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.2.2</version>
        </dependency>
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2、配置数据源信息

##数据源信息配置
#数据库地址
spring.datasource.url=jdbc:mysql://localhost:3306/springbootjpa?&serverTimezone=UTC&characterEncoding=utf8
#数据库用户名
spring.datasource.username=root
#数据库密码
spring.datasource.password=123456
#数据库驱动
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
#设置包别名（在Mapper映射文件中直接使用实体类名）
mybatis.type-aliases-package=com.yzh.mybatis.entity
#告诉系统在哪里去找mapper.xml文件（映射文件）
mybatis.mapperLocations=classpath:mappers/*.xml
#在控制台输出SQL语句日志
logging.level.com.yzh.mybatis.repository=debug
#让控制器输出的JSON字符串格式更美观
spring.jackson.serialization.indent-output=true
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3、创建实体类

package com.yzh.mybatis.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;

@Data
@AllArgsConstructor
@NoArgsConstructor
@ToString
public class MyUser {
    private String username;
    private String password;
}

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4、创建数据访问接口

package com.yzh.mybatis.repository;
import java.util.List;

import com.yzh.mybatis.entity.MyUser;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;

/**
 * MyBatis的Mapper映射接口
 */
@Mapper
@Repository //不写会在注入时报错，但不影响运行
public interface MyUserRepository {
	public List<MyUser> findAll();
}
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5、创建mapper映射文件

<?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.yzh.mybatis.repository.MyUserRepository">
	<select id="findAll"  resultType="MyUser">
		select * from user 
	</select>
</mapper>
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6、创建业务层

package com.yzh.mybatis.service;
import java.util.List;
import com.yzh.mybatis.entity.MyUser;

public interface MyUserService {
	public List<MyUser> findAll();
}

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package com.yzh.mybatis.service;
import java.util.List;

import com.yzh.mybatis.entity.MyUser;
import com.yzh.mybatis.repository.MyUserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class MyUserServiceImpl implements MyUserService{
	@Autowired
	private MyUserRepository myUserRepository;
	@Override
	public List<MyUser> findAll() {
		return myUserRepository.findAll();
	}
}

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7、创建控制器类

package com.yzh.mybatis.controller;
import java.util.List;

import com.yzh.mybatis.entity.MyUser;
import com.yzh.mybatis.service.MyUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MyUserController {
	@Autowired
	private MyUserService myUserService;
	@RequestMapping("/findAll")
	public List<MyUser> findAll(){
		return myUserService.findAll();
	}
}

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8、在应用程序的主类中扫描mapper接口

package com.yzh.mybatis;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import java.util.Arrays;

@MapperScan(basePackages ={"com.yzh.mybatis.Repository"})
@SpringBootApplication
public class MybatisApplication {

    public static void main(String[] args) {
        SpringApplication.run(MybatisApplication.class, args);
//        String[] strings={"1","2"};
//        System.out.println(Arrays.toString(strings));
    }

}

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基于注解

1、修改application.properties文件

删除如下配置

#设置包别名（在Mapper映射文件中直接使用实体类名）
mybatis.type-aliases-package=com.yzh.mybatis.entity
#告诉系统在哪里去找mapper.xml文件（映射文件）
mybatis.mapperLocations=classpath:mappers/*.xml
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2、删除mapper映射文件

删除src/main/resources文件夹下的mapper包

3、修改数据访问接口

package com.yzh.mybatis.repository;
import java.util.List;

import com.yzh.mybatis.entity.MyUser;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;

/**
 * MyBatis的Mapper映射接口
 */
//@Mapper
//@Repository //不写会在注入时报错，但不影响运行
public interface MyUserRepository {
	@Select("select * from user")
	public List<MyUser> findAll();
}
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