# Mybatis-Spring

# 基本概念

MyBatis-Spring 会帮助你将 MyBatis 代码无缝地整合到 Spring 中。它将允许 MyBatis 参与到 Spring 的事务管理之中，创建映射器 mapper 和 SqlSession 并注入到 bean 中，以及将 Mybatis 的异常转换为 Spring 的 DataAccessException。最终，可以做到应用代码不依赖于 MyBatis，Spring 或 MyBatis-Spring。

# 导入依赖

\pom.xml

<!--MySQL https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.12</version>
</dependency>

<!-- MyBatis https://mvnrepository.com/artifact/org.mybatis/mybatis -->
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.5</version>
</dependency>

<!-- Mybatis-Spring https://mvnrepository.com/artifact/org.mybatis/mybatis-spring -->
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis-spring</artifactId>
    <version>2.0.5</version>
</dependency>

<!-- Spring-JDBC https://mvnrepository.com/artifact/org.springframework/spring-jdbc -->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jdbc</artifactId>
    <version>5.2.8.RELEASE</version>
</dependency>

<!-- AspectJ Weaver https://mvnrepository.com/artifact/org.aspectj/aspectjweaver -->
<dependency>
    <groupId>org.aspectj</groupId>
    <artifactId>aspectjweaver</artifactId>
    <version>1.9.5</version>
</dependency>

# 使用

# 实体类

\com\example\dao\实体类名.java

@Data
public class User {
    private int id;
    private String name;
    private String pwd;
}

# dao 类

手动配置 sqlSession

public class UserMapperImpl {
    private SqlSessionTemplate sqlSession;

    public void setSqlSession(SqlSessionTemplate sqlSession) {
        this.sqlSession = sqlSession;
    }

    public List<User> selectUser() {
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        return mapper.selectUser();
    }
}

自动配置 sqlSession

public class UserMapperImpl2 extends SqlSessionDaoSupport implements UserMapper {
    public List<User> selectUser() {
        SqlSession sqlSession = getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        return mapper.selectUser();
    }
}

# 配置 Mybatis

\resources\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>
    <!-- 配置类型别名 -->
    <typeAliases>
        <package name="com.kuang.pojo"/>
    </typeAliases>

</configuration>

# 配置 Mapper

\com\example\dao\Mapper 名称.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.kuang.dao.UserMapper">

    <select id="selectUser" resultType="User">
        select * from user
    </select>

</mapper>

# 配置 Bean

\resources\spring-dao.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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">


    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"></property>
        <property name="url"
                  value="jdbc:mysql://127.0.0.1:3306/mybatis?serverTimezone=UTC&amp;useSSL=false&amp;useUnicode=true&amp;characterEncoding=utf8"></property>
        <property name="username" value="root"></property>
        <property name="password" value=""></property>
    </bean>

    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <!-- 绑定Mybatis配置文件-->
        <property name="configLocation" value="classpath:mybatis-config.xml"></property>
        <property name="mapperLocations" value="classpath:com/kuang/dao/*.xml"/>
    </bean>

    <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
        <!--只能用构造器注入sqlSessionFactory，因为没有set方法-->
        <constructor-arg index="0" ref="sqlSessionFactory"></constructor-arg>
    </bean>

    <bean id="userMapper" class="com.kuang.dao.UserMapperImpl">
        <property name="sqlSession" ref="sqlSession"></property>
    </bean>

    <bean id="userMapper2" class="com.kuang.dao.UserMapperImpl2">
        <property name="sqlSessionFactory" ref="sqlSessionFactory"></property>
    </bean>

</beans>

# 测试类

public class MyTest {
    @Test
    public void test() {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("spring-dao.xml");
        UserMapper userMapper = context.getBean("userMapper2", UserMapper.class);
        for (User item : userMapper.selectUser()) {
            System.out.println(item);
        }
    }
}

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