1, Gossip

The weekend is coming again. Today, finish the spring blog, and then start the review of mybatis. I read it in July last year. If I don't write a blog, I'll soon forget it. Ha ha

2, Review mybatis and introduce integration methods

1. mybatis review

mybatis has written a simple example before. You can take a look at the previous blog
Introduction to Mybatis and construction of the first simple demo

2. Integration method 1: use SqlSessionTemplate in mybatis spring

Can refer to Official document of mybatis spring

First, we import the related dependencies into the pom file

<dependencies>
        <!--MySQL drive-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>
        <!--Mybatis-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.27</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.8</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.6</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.8</version>
        </dependency>
    </dependencies>

In the original mybatis configuration file, we only put alias configuration. Of course, this configuration file can be completely omitted. All relevant configurations can be put into the spring configuration file

<?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>
    
    <typeAliases>
        <package name="com.decade.entity"/>
    </typeAliases>
</configuration>

Next, let's configure the relevant configuration files of spring management data source
Create a spring Dao XML to manage database connection information

<?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">

    <!-- Configure data source, using spring Data source replacement for mybatis， c3p0 druid dbcp -->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <!--Drive configuration, com.mysql.jdbc.driver -->
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/decade_test?useUnicode=true&amp;characterEncoding=UTF-8"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
    </bean>

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

    <!--establish sqlSessionTemplate，Replace the original sqlSession -->
    <bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
        <!--because sqlSessionTemplate No, set Method, so we use constructor injection -->
        <constructor-arg index="0" ref="sqlSessionFactory"/>
    </bean>
</beans>

Note: if you want to configure the SqlSessionTemplate instance through annotation, you can refer to this section

@Configuration
public class MyBatisConfig {
 @Bean
 public SqlSessionTemplate sqlSession() throws Exception {
   return new SqlSessionTemplate(sqlSessionFactory());
 }
}

Then there is the general configuration file ApplicationContext XML, we just need to import the above configuration file

<?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">

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

    <bean id="userDao" class="com.decade.mapper.UserDaoImpl">
        <property name="sqlSessionTemplate" ref="sqlSessionTemplate"/>
    </bean>
</beans>

Different from mybatis, we need to add an implementation class of UserDao to obtain sqlSessionTemplate as a business class

package com.decade.mapper;

import com.decade.entity.User;
import org.mybatis.spring.SqlSessionTemplate;

import java.util.List;

public class UserDaoImpl implements UserDao{
    // The sqlSessionTemplate here replaces the original sqlSession
    private SqlSessionTemplate sqlSessionTemplate;

    public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate) {
        this.sqlSessionTemplate = sqlSessionTemplate;
    }

    @Override
    public List<User> getUserInfo() {
        UserDao mapper = sqlSessionTemplate.getMapper(UserDao.class);
        return mapper.getUserInfo();
    }
}

Finally, we create a new test class. We only need to get the bean of UserDao's implementation class from the spring context

import com.decade.mapper.UserDao;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class UserDaoTest {

    @Test
    public void test() {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserDao userDao = context.getBean("userDao", UserDao.class);
        userDao.getUserInfo().forEach(System.out::println);
    }
}

The operation results are as follows

3. Integration method 2: use SqlSessionDaoSupport in mybatis spring

Mode 2 is simpler than mode 1
It does not need to be injected through the set method, but only needs to inherit an abstract SqlSessionDaoSupport class

package com.decade.mapper;

import com.decade.entity.User;
import org.mybatis.spring.support.SqlSessionDaoSupport;

import java.util.List;

public class UserDaoImpl2 extends SqlSessionDaoSupport implements UserDao {
    @Override
    public List<User> getUserInfo() {
        return getSqlSession().getMapper(UserDao.class).getUserInfo();
    }
}

Use spring Dao in this way The sqlsession in the XML configuration file does not need to be configured
applicationContext.xml is configured as follows

<?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">

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

    <bean id="userDao2" class="com.decade.mapper.UserDaoImpl2">
        <property name="sqlSessionFactory" ref="sqlSessionFactory"/>
    </bean>
</beans>

Write test class

import com.decade.mapper.UserDao;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class UserDaoTest {

    @Test
    public void test() {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserDao userDao = context.getBean("userDao2", UserDao.class);
        userDao.getUserInfo().forEach(System.out::println);
    }
}

Run the test class and the result is the same as that in mode 1

If there is any mistake, please correct it