SpringBoot--整合MyBatis（XML方式）

落日映苍穹つ 2021-08-14 00:18 480阅读 0赞

### 整合MyBatis（XML方式） ###

1. 添加MySQL 连接驱动依赖、SpringBoot Mybatis 依赖

完整pom.xml文件如下：

<?xml version="1.0" encoding="UTF-8"?>
    <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.example</groupId>
        <artifactId>demo</artifactId>
        <version>1.0.0</version>
        <packaging>jar</packaging>
    
        <name>hello</name>
        <description>Demo project for Spring Boot</description>
    
        
        <properties>
            <mybatis-spring-boot>1.3.0</mybatis-spring-boot>
            <mysql-connector>5.1.39</mysql-connector>
        </properties>
        
       
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.1.1.RELEASE</version>
            <relativePath/> 
        </parent>
    
        <dependencies>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>${mysql-connector}</version>
            </dependency>
    
            
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>${mybatis-spring-boot}</version>
            </dependency>
    
            
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>ch.qos.logback</groupId>
                <artifactId>logback-classic</artifactId>
            </dependency>
    
             
            <dependency>
                <groupId>org.slf4j</groupId>
                <artifactId>jcl-over-slf4j</artifactId>
            </dependency>
        </dependencies>
    
    	
    	
    </project>

整合MyBatis的核心依赖MyBatis-Spring-Boot-Starter提供：

*  自动检测现有的DataSource
 *  将创建并注册SqlSessionFactory的实例，该实例使用SqlSessionFactoryBean将该DataSource作为输入进行传递
 *  将创建并注册从SqlSessionFactory中获取的SqlSessionTemplate的实例。
 *  自动扫描您的mappers，将它们链接到SqlSessionTemplate并将其注册到Spring上下文，以便将它们注入到您的bean中。

因此，引入该Starter之后，只需要定义一个DataSource即可（application.properties中可配置），它会自动创建使用该DataSource的SqlSessionFactoryBean以及SqlSessionTemplate。会自动扫描你的Mappers，连接到SqlSessionTemplate，并注册到Spring上下文中。

配置application.yml文件

*  配置数据库连接信息（数据源）

spring:
        #数据源
      datasource:
        url: jdbc:mysql://localhost:3306/springbootdb??useUnicode=true&characterEncoding=UTF-8
        username: root
        password: 123
        driver-class-name: com.mysql.jdbc.Driver

*  配置mybatis

#mybatis配置
    mybatis:
      typeAliasesPackage: com.example.mybaitsxml.dao.entity
      mapperLocations: classpath:mapper/*.xml #configLocation: classpath:/mybatis-config.xml

注：通常，若mybatis配置信息较少，只是针对基本配置无需复杂配置，则只需在application.yml文件中配置即可，否则最好配置在 mybatis-config.xml中。

代码实现

工程结构：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70]

*  controller层

@Slf4j
    @RestController
    @RequestMapping("/web")
    public class UserController { 
        @Autowired
        private UserService userService;
    
        @GetMapping("/queryAllUsers")
        public List<User> queryAllUsers(){ 
            return userService.queryAllUsers();
        }
    }

*  service层（实现）

@Slf4j
    @Service
    public class UserServiceImpl implements UserService { 
        @Autowired
        private UserMapper userMapper;
    
        @Override
        public List<User> queryAllUsers() { 
            log.info("/queryAllUsers start...");
            return userMapper.queryAllUsers();
        }
    }

*  dao层

dao层分为数据库实体类（entity）和数据库操作mapper接口（mapper）

**entity:**

@Data
    public class User { 
        private String name ;
        private String sex;
        private Integer age;
        private Integer classNo;
    
    }

**mapper:**

public interface UserMapper { 
        List<User> queryAllUsers();
    }

*  mapper.xml实现

<?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.example.mybaitsxml.dao.mapper.UserMapper" >
        <resultMap id ="UserInfoMap" type="com.example.mybaitsxml.dao.entity.User">
            <result column="name_" property="name"/>
            <result column="sex" property="sex"/>
            <result column="age" property="age"/>
            <result column="class_no" property="classNo"/>
        </resultMap>
    
        <select id = "queryAllUsers" resultMap="UserInfoMap">
            select
              name_,
              sex,
              age,
              class_no
            from
              tbl_user
        </select>
    </mapper>

测试：  
![在这里插入图片描述][20191213181107190.png]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70]: /images/20210813/cb3d4a9057bc4effbfcda72c129e6b18.png
[20191213181107190.png]: /images/20210813/4ecf32b31a924396aec1c36be2a06fba.png