spring boot集成mybatis（xml配置模式）

一.项目所需材料：

spring boot、mybatis

pom文件配置如下：

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.0</version>
        <relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
        <java.version>1.8</java.version>
    </properties>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.38</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.0.1</version>
        </dependency>
    </dependencies>

二.项目目录结构

三.项目代码

UserEntity.java

import java.io.Serializable;

public class UserEntity implements Serializable {

    private Long id;

    private String user_name;

    private String passWord;

    private String realName;


    public Long getId() {
        return id;
    }

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

    public String getUser_name() {
        return user_name;
    }

    public void setUser_name(String user_name) {
        this.user_name = user_name;
    }

    public String getPassWord() {
        return passWord;
    }

    public void setPassWord(String passWord) {
        this.passWord = passWord;
    }

    public String getRealName() {
        return realName;
    }

    public void setRealName(String realName) {
        this.realName = realName;
    }
}

UserMapper.java

@Repository
public interface UserMapper {
    UserEntity queryUser(int id);
}

UserService.java

@Service
public class UserService {

    @Autowired
    UserMapper userMapper;

    public UserEntity Sel(int id) {
        return userMapper.queryUser(id);
    }
}

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.mybatis14.mapper.UserMapper">

       <!-- <resultMap id="BaseResultMap" type="***.com.mybatis14.entity.UserEntity">
            <result column="id" jdbcType="INTEGER" property="id" />
            <result column="user_name" jdbcType="VARCHAR" property="user_name" />
            <result column="passWord" jdbcType="VARCHAR" property="passWord" />
            <result column="realName" jdbcType="VARCHAR" property="realName" />
        </resultMap>-->

    <select id="queryUser" resultType="***.com.mybatis14.entity.UserEntity">
        select * from user where id = #{id}
    </select>

</mapper>

说明：

1.resultMap部分可以写，也可以不写，均能正常运行。

2.select id需要与具体的Mapper中的方法定义相对应（本示例为：queryUser）。

UserController.java

@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserService userService;

    @RequestMapping("/get")
    public UserEntity getUserByName(int id) {
        return userService.Sel(id);
    }
}

application.properties

spring.datasource.url=jdbc:mysql://localhost:3306/business?useUnicode=true&characterEncoding=utf8&useSSL=false
spring.datasource.username=root
spring.datasource.password=******
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

mybatis.mapper-locations=classpath:mapping/*Mapper.xml
#mybatis.type-aliases-package=***.com.mybatis14.entity

说明：mybatis.type-aliases-package=***.com.mybatis14.entity可配也可以不配，均能正常运行。

Mybatis14Application.java

@MapperScan("***.com.mybatis14.mapper")
@SpringBootApplication
public class Mybatis14Application {
    public static void main(String[] args) {
        SpringApplication.run(Mybatis14Application.class, args);
    }
}

四.启动并测试

输入：http://localhost:8080/user/get?id=1

返回结果：

参考：https://www.cnblogs.com/lvchengda/p/12619520.html

=================================================

补充：一种极简的使用方式（根据官方示例）：

=================================================

<dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.18.16</version>
    </dependency>
    <dependency>
      <groupId>com.baomidou</groupId>
      <artifactId>mybatis-plus-boot-starter</artifactId>
      <version>3.1.1</version>
    </dependency>

lombok用于@Data及@RequiredArgsConstructor（代替@Autowired）

在名为mapper的package下建立业务所需的mapper:

public interface GroupMapper  extends BaseMapper<auth_group> {
    auth_group getGroup(@Param("id") int id);
}

然后在项目的启动类中标记扫描路径：

@MapperScan("*****.com.cn.mapper")

在controller中调用代码写：

    @Autowired
    private GroupMapper groupMapper;

 @RequestMapping("group")
    public auth_group getgroup(@RequestParam("id") int id)
    {
        auth_group list = groupMapper.getGroup(id);
        return list;
    }

结果：

 其中，controller中会出现警告（但不影响运行）：

Could not autowire. No beans of 'GroupMapper' type found. more... (Ctrl+F1)

只需要在Mapper中添加属性：@Repository即可。