On the basis of Mybatis introduction (a), integrated into SpringBoot.

A, rely on

Compared with the Mybatis version, the dependency is changed to Mybatis -spring-boot-starter, which already contains the Mybatis dependency.

  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-jdbc</artifactId>
    </dependency>
    <dependency>
      <groupId>org.mybatis.spring.boot</groupId>
      <artifactId>mybatis-spring-boot-autoconfigure</artifactId>
    </dependency>
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
    </dependency>
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
    </dependency>
  </dependencies>
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SpringBootMybatis rely on

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.4</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.10</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

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Configuration file

In SpringBoot, the configuration of the previous version of mybatis-config.xml is integrated in Spring. The configuration includes data source and Mybatis Mapper mapping

# data source
spring:
  datasource:
    password: root
    username: root
    url: jdbc:mysql://localhost:3306/test? characterEncoding=utf-8&useSSL=false&serverTimezone=UTC
    driver-class-name: com.mysql.cj.jdbc.Driver
# mybatis
mybatis:
  mapper-locations: classpath:mapper/*.xml
  configuration:
    map-underscore-to-camel-case: true
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Note: Mapper-locations is the function of mybatis-config. XML. By configuring the mapper. XML path, it automatically scans the matching mapper. XML file. An error will be reported if there is no configuration:

org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.stopping.springmybatis.mapper.UserMapper.selectUser
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Configure an alias

 <select id="selectUser" resultType="com.stopping.springmybatis.model.User">
        select * from user order by id;
    </select>
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For example, when compiling resultType in mapper. XML, the full pathname of entity class should always be written down. In order to improve efficiency, type-aliases-package can be configured in the configuration file to follow the package pathname.

 <select id="selectUser" resultType="User">
        select * from user order by id;
    </select>
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mybatis:
  type-aliases-package: com.stopping.springmybatis.model
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Hump nomenclature

mybatis:
  configuration:
    map-underscore-to-camel-case: true
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When map-underscore-to camel-case: True is turned on, the underscores of the database fields are automatically mapped to the camel name of the entity class. The entity returned by resultType is the same as the database field by default. Mybatis will automatically map the corresponding data type and field.

Mybatis will automatically map to userId if the database table field is user_id according to the specification we use hump command.

Three, test,

@SpringBootTest(classes = SpringMybatisApplication.class) class UserMapperTest { @Resource UserMapper userMapper; @Test void selectUser() { userMapper.selectUser().stream().forEach(user -> { System.out.println(user.getUsername()); }); }}Copy the code

The results of

admin
tom
job
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