Mybatis 初始化

Spring 环境

pom.xml

<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.2</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.47</version>
</dependency>

spring-mapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                           http://www.springframework.org/schema/beans/spring-beans.xsd
                           http://www.springframework.org/schema/context
                           https://www.springframework.org/schema/context/spring-context.xsd
                           http://www.springframework.org/schema/tx
                           http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!-- 配置整合mybatis -->
    <!-- 关联数据库文件 -->
    <context:property-placeholder location="classpath:database.properties"/>

    <bean id="dataSource"
          class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${jdbc.driver}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>

    <!-- 配置SqlSessionFactory对象 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 注入数据库连接池 -->
        <property name="dataSource" ref="dataSource"/>
        <!-- 配置MyBaties全局配置文件：mybatis-config.xml -->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        <!--Mapper.xml文件位置-->
        <property name="mapperLocations" value="classpath*:mapper/*.xml"/>
    </bean>

    <!-- 配置扫描Dao接口包，动态实现Dao接口注入到spring容器中 -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- 注入sqlSessionFactory -->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
        <!-- 给出需要扫描Dao接口包 -->
        <property name="basePackage" value="com.example.mapper"/>
    </bean>

    <!-- 配置事务管理器 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <!-- 注入数据库连接池 -->
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <!--事务注解支持-->
    <tx:annotation-driven transaction-manager="transactionManager" proxy-target-class="true"/>
</beans>

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>
    <!-- 开启驼峰映射，为自定义的SQL语句服务-->
    <!--设置启用数据库字段下划线映射到java对象的驼峰式命名属性，默认为false-->
    <settings>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
    <!--配置别名，默认为实体类类名-->
    <typeAliases>
        <package name="com.example.entity"/>
    </typeAliases>
</configuration>

Mapper层接口

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

mapper.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.example.mapper.UserMapper">
    <select id="selectUser" resultType="com.example.entity.User">
        select * from user
    </select>
</mapper>

测试

public class UserTest {

    @Autowired
    private UserMapper userMapper;

    @Test
    public void MapperTest() {
        List<User> userList = userMapper.queryAllUser();
        for (User user : userList) {
            System.out.println(user);
        }
    }

    @Test
    public void selectUser() {
        InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session =    sqlSessionFactory.openSession();
        // 方法一。
        List<User> users = session.selectList("com.example.mapper.UserMapper.selectUser");
        // 方法二。
        UserMapper mapper = session.getMapper(UserMapper.class);
        List<User> users = mapper.selectUser();

        for (User user: users){
            System.out.println(user);
        }
        session.close();
    }
}

Spring Boot 环境

pom.xml

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.1.1</version>
</dependency>

applicationContext.xml

spring:
  datasource:
  username: root
  password: 123456
  url: jdbc:mysql://localhost:3306/springboot?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
  driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:
  mapper-locations: classpath:com/example/mapper/*.xml
  type-aliases-package: com.example.entity

dao层接口

@Mapper
public interface UserMapper {
    List<User> selectUser();
}

• @Mapper：表示本类是一个 MyBatis 的 Mapper
• @MapperScan注解，可以在主启动类上添加该注解，自动扫描包路径下的所有接口，可省略@Mapper注解。

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

mapper.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.example.mapper.UserMapper">
    <select id="selectUser" resultType="com.example.entity.User">
        select * from user
    </select>
</mapper>

测试

public class UserTest {

    @Autowired
    private UserMapper userMapper;

    @Test
    public void MapperTest() {
        List<User> userList = userMapper.queryAllUser();
        for (User user : userList) {
            System.out.println(user);
        }
    }
}