Spring 整合Mybatis (最全知识点，看这一篇就够了)

本文链接：https://blog.youkuaiyun.com/m0_61495539/article/details/134089747

1 回顾Mybatis

1.1 导入相关依赖

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.13</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.33</version>
        </dependency>

1.2 创建实体类

package com.example.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data

public class User {
    private Integer id;
    private String name;
    private String sex;
    private Integer age;
    private String address;
}

1.3 编写mybatis-config.xml 配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
        <!--  起别名  -->
    <typeAliases>
        <package name="com.example.pojo"/>
    </typeAliases>
    
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=utf8&amp;serverTimezone=UTC"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="com/example/mapper/UserMapper.xml"/>
    </mappers>
</configuration>

1.4 编写Mapper接口

package com.example.mapper;

import com.example.pojo.User;

import java.util.List;

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

1.5 编写SQL映射文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.example.mapper.UserMapper">

    <select id="select" resultType="com.example.pojo.User">
        select * from mybatis.user;
    </select>
</mapper>

1.6 测试

import com.example.mapper.UserMapper;
import com.example.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import java.io.InputStream;
import java.util.List;

public class MyTest {
    @Test
    public void test() throws Exception {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        SqlSession sqlSession = sqlSessionFactory.openSession(true);

        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        List<User> users = userMapper.select();

        System.out.println(users);

        sqlSession.close();
    }
}

2 Spring整合Mybatis

2.1 UserMapper接口

package com.example.mapper;

import com.example.pojo.User;

import java.util.List;

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

2.2 实现类

package com.example.mapper;

import com.example.pojo.User;
import org.mybatis.spring.SqlSessionTemplate;

import java.util.List;

public class UserMapperImpl implements UserMapper{

//    之前，我们的所有操作都使用sqlSession来执行，现在我们都使用sqlSessionTemplate
    private SqlSessionTemplate sqlSession;

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

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

2.3 SQL映射文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.example.mapper.UserMapper">

    <select id="select" resultType="com.example.pojo.User">
        select * from mybatis.user;
    </select>
</mapper>

2.4 编写配置文件

使用Spring的数据源替换Mybatis的配置
    <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://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"></property>
        <property name="username" value="root"></property>
        <property name="password" value="123456"></property>
    </bean>

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

    <!-- SqlSessionTemplate: 就是我们使用的sqlSession   -->
    <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
        <!--  只能使用构造器注入sqlSessionFactory, 因为它没有set方法  -->
        <constructor-arg index="0" ref="sqlSessionFactory"/>
    </bean>

2.5 导入上述的配置文件，并注册bean

<?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 http://www.springframework.org/schema/beans/spring-beans.xsd">

    <import resource="spring-dao.xml"/>

    <!--  将自己写的实现类注册到bean中  -->
        <bean id="userMapper" class="com.example.mapper.UserMapperImpl">
            <property name="sqlSession" ref="sqlSession"></property>
        </bean>
</beans>

2.6 测试

import com.example.mapper.UserMapper;
import com.example.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import java.io.InputStream;
import java.util.List;

public class MyTest {
    @Test
    public void test() throws Exception {

        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserMapper userMapper = context.getBean("userMapper", UserMapper.class);

        for (User user : userMapper.select()) {
            System.out.println(user);
        }
    }

如果想要了解Spring的相关知识，可以查看Spring框架介绍【最全知识点】-优快云博客