Spring-MyBatis整合

Spring-MyBatis整合

步骤

一 导入相关的jar包

• junit

 <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

• mybatis

<dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>

• mysql数据库

 <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.15</version>
        </dependency>

• spring相关的

 <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.9.RELEASE</version>

• spring操控数据库spring-jdbc

 <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>

• aop织入

 <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.8.13</version>
        </dependency>

• spring-mybatis

<dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.2</version>
        </dependency>

导入上面的jar之后，基本的mybatis-spring就已经可以开发了

=回忆mybatis====================

整理之前我们回忆一下mybatis

mybatis相关的jar我们上面已经导入了，这里就不强调了

• 编写实体类
• 编写工具类获取sqlSession 但是有了spring以后，就不再需要这里步了，直接交给spring 管理sqlSession
• 编写核心配置文件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>
    <properties resource="db.properties">
    </properties>
    <settings>
        <setting name="logImpl" value="LOG4J"/>
    </settings>
    <typeAliases>
        <package name="com.wcz.pojo"/>
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/wcz/dao/UserMapper.xml"/>
    </mappers>


</configuration>

• 编写接口
• 编写Mapper-xml
• 测试

==================================================================================================
接下来接着讲spring-mybatis
**二 编写配置文件 **

• 配置spring文件

配置spring俗称bean.xml文件要导入aop 下面是完整的bean.xml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"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       https://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/aop
       https://www.springframework.org/schema/aop/spring-aop.xsd">

</beans>

• spring之后要用spring的数据源替代MyBatis的位置，前面也导入了spring-jdbc jar包，我们要在bean.xml中使用spring提供的jdbc

<bean id="datasource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="com.mysql.cj.jdbc"/>
    <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useUnicode=true&amp;characterEncoding=UTF-8&amp;useSSL=false&amp;serverTimezone=GMT%2B8"/>
    <property name="username" value="root"/>
    <property name="password" value="123456"/>

</bean>

• 通过数据源datasource获取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/wcz/mapper/*.xml"/>

    </bean>

• 要执行sql，mybaits中要创建sqlSession对象，但是在spring，用SqlSessionTemplate即可,SqlSessionTemplate还是线程安全。

 <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
    <!--只能用构造器注入sqlSession 源码中没有set方法。具体请看源码-->
        <constructor-arg index="0" ref="sqlSessionFactory"/>
    </bean>

• 创建实现UserMapper接口类

public class UserMapperImpl implements UserMapper {
    private SqlSessionTemplate sqlSession;
    public void setSqlSession(SqlSessionTemplate sqlSession) {
    this.sqlSession = sqlSession;
}
    public List<User> queryUser() {
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        List<User> userList = mapper.queryUser();
        return userList;
    }
}

这时候就有小伙伴有疑问了，为了spring整合mybatis要多出一个实现类？再说了mybatis不也可以实现这个骚操作吗？答案是，因为spring在ioc中已经接管了seSession，或者说接管mybatis中很多对象，而你们别忘了，spring可以自动创建对象 (setter注入) 而mybatis不能，那怎么自动创建呢？只能我们手动给它加一个set方法

这时候你可能又惊讶心里又有疑问，卧槽！spring这么强大，ioc和aop 接管了所有的对象，都能替代mybatis了，那为什么还要用mybatis呢？直接所有的操作在bean.xml下完成就行了嘛。这个问题问得好！你为什么不问问神奇的海螺呢？ 哈哈，你想，mybatis只用来单单写sql语句，spring用来处理和接管对象，那疑问不就解开了吗？哈哈哈哈哈哈哈哈！！~~

三 测试

public class MyTest {
    @Test
    public void Test() throws IOException {
       ApplicationContext Context = new ClassPathXmlApplicationContext("spring-dao.xml");
        UserMapper queryUser = Context.getBean("queryUser", UserMapper.class);
        List<User> userList = queryUser.queryUser();
        for (User user:userList){
            System.out.println(user);
        }

    }
}

**配置spring-dao.xml文件 **

这里基本都是固定的写法，获取sql数据源，获取seSession等

<?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:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       https://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/aop
       https://www.springframework.org/schema/aop/spring-aop.xsd">
<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/mybatis?useUnicode=true&amp;characterEncoding=UTF-8&amp;useSSL=false&amp;serverTimezone=GMT%2B8"/>
    <property name="username" value="root"/>
    <property name="password" value="123456"/>
</bean>
    <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/wcz/mapper/*.xml"/>

    </bean>
    <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
        <constructor-arg index="0" ref="sqlSessionFactory"/>
    </bean>
</beans>