怎样通过Spring整合Mybatis来实现业务

目录

1.导入依赖

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.33</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.13</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>6.0.13</version>
        </dependency>
        <!--用Spring操作数据库，还需要一个spring-jdbc-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>6.0.13</version>
        </dependency>
        <!--AOP织入-->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.9.1</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>3.0.2</version>
        </dependency>
    </dependencies>

2. spring配置文件

spring整合mybatis之后，就不再需要mybatis的配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
		https://www.springframework.org/schema/beans/spring-beans.xsd">
    <!--Spring整合Mybatis，省略了Mybatis的核心配置文件，转而在Spring的配置文件中配置Mybatis-->
    <!--datasource-->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/user?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
        <property name="username" value="root"/>
        <property name="password" value="123456"/>
    </bean>

    <!--sqlSessionFactory-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        <property name="mapperLocations" value="classpath:com/sun/mapper/*.xml"/>
    </bean>

    <!--SqlSessionTemplate:就是我们使用的sqlSession,这个是spring提供的-->
    <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
        <!--我们只能使用构造器注入，因为没有set方法-->
        <constructor-arg name="sqlSessionFactory" ref="sqlSessionFactory"/>
    </bean>

 上面的配置文件是固定的，配置文件需要三个bean

• dataSource                                     用来连接数据库
• sqlSessionFactory                        用来创建sqlSession
• sqlSession                                      用来创建sqlSession的bean

 3.编写实体类(原mybatis的步骤)

public class User {
    private int id;
    private String name;
    private int age;

}

4.编写接口(原mybatis的步骤)

public interface UserMapper {

   public List<User> selectUser();

}

5.编写xml映射文件(原mybatis的步骤)

<?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.sun.mapper.UserMapper">
    <select id="selectUser" resultType="user">
        select * from user.tb_user
    </select>
</mapper>

6.编写接口实例

public class UserMapperImpl implements UserMapper{

    //之前使用Mybatis时候，我们用的是sqlSession，现在用Spring整合Mybatis，我们使用Spring提供的SqlSessionTemplate(相当于sqlSession)
    private SqlSessionTemplate sqlSessionTemplate;

    public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate) {
        this.sqlSessionTemplate = sqlSessionTemplate;
    }
    @Override
    public List<User> selectUser() {
        UserMapper mapper = sqlSessionTemplate.getMapper(UserMapper.class);
        return mapper.selectUser();
    }
}

 

7.将实例注册到spring中

<bean id="UserMapperImpl" class="com.sun.mapper.UserMapperImpl">
        <property name="sqlSessionTemplate" ref="sqlSession"/>
    </bean>

8.测试

直接获取实例的bean即可

public class MyTest {

    @Test
    public void selectTest(){
        ApplicationContext context = new ClassPathXmlApplicationContext("spring-mybatis.xml");
        UserMapper userMapperImpl = (UserMapper) context.getBean("UserMapperImpl");
        List<User> users = userMapperImpl.selectUser();
        for (User user : users) {
            System.out.println(user);
        }
    }
}

总的来说，使用Spring整合Mybatis，思想还是不变，只不过形式是采用了Spring的ioc容器

9.第二种方式

• Spring提供了一个SqlSessionDaoSupport类，可以通过getSqlSession方法直接获取SqlSession，原本我们是通过SqlSessionTemplate作为中间人，现在通过这个方法我们不再需要SqlSessionTemplate

public class UserMapperImpl2 extends SqlSessionDaoSupport implements UserMapper{

    //这个类继承了SqlSessionDaoSupport，可以直接get一个SqlSession
    @Override
    public List<User> selectUser() {
        SqlSession sqlSession = getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        return mapper.selectUser();
    }
}

 将这个类放到Spring中：

  <bean id="UserMapperImpl2" class="com.sun.mapper.UserMapperImpl2">
        <property name="sqlSessionFactory" ref="sqlSessionFactory"/>
    </bean>

测试： 

   @Test
    public void selectTest2(){
        ApplicationContext context = new ClassPathXmlApplicationContext("spring-mybatis.xml");
        UserMapper userMapperImpl2 = (UserMapper) context.getBean("UserMapperImpl2");
        List<User> users = userMapperImpl2.selectUser();
        for (User user : users) {
            System.out.println(user);
        }
    }