0️⃣初始配置
🚩pom.xml导入依赖
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>org.example</groupId>
    <artifactId>SMDemo1</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <dependencies>
        <!--mybatis与数据库相关-->
        <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>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.23</version>
        </dependency>
        <!--spring-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.10.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.1.10.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.4</version>
        </dependency>
        <!--spring与mybatis关联-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.2</version>
        </dependency>
        <!--其他-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter</artifactId>
            <version>5.9.0</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>
</project>
 🚩dao类
package com.app.dao;
import com.app.pojo.User;
import java.util.List;
public interface UserDao {
    List<User> selectUser();
}
 🚩pojo类
package com.app.pojo;
public class User {
    private int id;
    private String name;
    private String password;
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}
 🚩dao.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.app.dao.UserDao">
    <select id="selectUser" resultType="com.app.pojo.User">
        select *
        from user
    </select>
</mapper>
 
 1️⃣整合前MyBatis代码编写
在以前仅使用MyBatis的时候,我们编写完配置文件、dao类、dao.xml、pojo类后,会编写下面的代码5步生成UserDao 代理类进行测试:
    // 获取流对象,读取核心配置文件
    InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
    // 创建 sqlSessionFactoryBuilder 工厂构建者对象
    SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
    // 获取 sqlSessionFactory 工厂对象
    SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(is);
    // 获取 SqlSession 对象
    SqlSession sqlSession = sqlSessionFactory.openSession();
    // 获取 UserDao 代理类对象
    UserDao userDao = sqlSession.getMapper(UserDao.class);
    // 使用 UserDao 的相关方法
    userDao.XXX();
    // 提交事务
    sqlSession.commit();
    // 释放资源
    sqlSession.close();
 上面代码可以看出,我们需要通过:
SqlSessionFactoryBuilder -> SqlSessionFactory -> SqlSession -> UserDao
来一步步获得UserDao的代理类
2️⃣使用SqlSessionTemplate
在Spring 整合MyBatis中,我们将上面的5步生成 UserDao 代理类的java代码写成xml配置在Sping的配置文件中。通过下面的步骤来获取UserDao的代理类:
SqlSessionFactoryBean -> SqlSessionTemplate -> UserDaoImpl -> UserDao
在整合MyBatis开发中,我们可以不编写MyBatis的配置文件,关于数据源等配置在Spring配置文件中编写:
🚩创建Spring配置文件spring-config.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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd">
</beans>
 🚩生成数据源
    <!--生成Druid数据源-->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/db_study"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
    </bean>
 🚩注册SqlSessionFactory
    <!--注册SqlSessionFactory-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!--注入数据源-->
        <property name="dataSource" ref="dataSource"/>
        <!--关联Mapper-->
        <property name="mapperLocations" value="classpath:com.app.dao/UserMapper.xml"/>
    </bean>
 🚩注册SqlSessionTemplate
    <!--注册sqlSessionTemplate-->
    <bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
        <!--关联sqlSessionFactory,利用构造器注入-->
        <constructor-arg index="0" ref="sqlSessionFactory"/>
    </bean>
 🚩编写UserDaoImpl实现类
使用SqlSessionTemplate对MyBatis进行整合时,我们仍需要编写UserDaoImpl实现类,然后在spring-config.xml中进行注册。在UserDaoImpl实现类中,我们添加 SqlSession 属性,这样将之前注册的SqlSessionTemplate进行注入。
在下面使用MapperScannerConfigurer开发时,我们将不再需要编写UserDaoImpl实现类。
package com.app.dao;
import com.app.pojo.User;
import org.apache.ibatis.session.SqlSession;
import org.mybatis.spring.SqlSessionTemplate;
import java.util.List;
public class UserDaoImpl implements UserDao{
    private SqlSession sqlSession;
    public void setSqlSession(SqlSessionTemplate sqlSession) {
        this.sqlSession = sqlSession;
    }
    public List<User> selectUser() {
        UserDao userDao = sqlSession.getMapper(UserDao.class);
        return userDao.selectUser();
    }
}
 🚩注册userDao实现
    <!--注册userDao实现-->
    <bean id="userDaoImpl" class="com.app.dao.UserDaoImpl">
        <property name="sqlSession" ref="sqlSessionTemplate"/>
    </bean>
 🚩测试
import com.app.dao.UserDao;
import com.app.pojo.User;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import java.util.List;
public class UserTest {
    @Test
    public void test() {
        ApplicationContext context = new ClassPathXmlApplicationContext("spring-config.xml");
        UserDao userDao = (UserDao) context.getBean("userDaoImpl");
        List<User> users = userDao.selectUser();
        for (User user : users) System.out.println(user);
    }
}
 🚩项目结构
   1️⃣使用MapperScannerConfigurer
使用MapperScannerConfigurer对MyBatis进行整合,我们就不需要编写UserDaoImpl实现类。通过以下步骤生成UserDao:
SqlSessionFactoryBean -> MapperScannerConfigurer -> UserDao
Mybatis在与Spring集成的时候可以配置MapperFactoryBean来生成Mapper接口的代理。MapperFactoryBean的出现为了代替手工使用SqlSessionDaoSupport或SqlSessionTemplate编写数据访问对象(DAO)的代码,使用动态代理实现。
🚩修改Spring配置文件spring-config.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">
    <!--扫描所有要被Spring管理的实例-->
    <context:component-scan base-package="com.app"/>
    <!--生成Druid数据库连接池对象-->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/db_study"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
    </bean>
    <!--配置SqlSessionFactory-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!--注入数据源-->
        <property name="dataSource" ref="dataSource"/>
        <property name="typeAliasesPackage" value="com.app.pojo"/>
    </bean>
</beans>
 🚩注册MapperScannerConfigurer:
    <!--扫描所有的dao,将所有dao对应的dao.xml生成对应的实例-->
    <bean id="mapperScanner" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!--依赖于sqlSessionFactory-->
        <property name="sqlSessionFactory" ref="sqlSessionFactory"/>
        <property name="basePackage" value="com.app.dao"/>
    </bean>
 🚩测试:
package com.app.test;
import com.app.dao.UserDao;
import com.app.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.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
public class AppTest {
    @Test
    public void test() {
        ApplicationContext context = new ClassPathXmlApplicationContext("spring-config.xml");
        UserDao userDao = context.getBean(UserDao.class);
        List<User> users = userDao.selectUser();
        for (User user : users) System.out.println(user);
    }
}
 🚩项目结构:
   

















