Spring和Mybatis的整合

• 创建工程，导入所依赖的jar包(这里我们使用DBCP连接池来管理数据源)                                                                                                                                                 

• 原始Dao整合方法：需要我们编写Dao接口和Dao实现类，在Dao实现类中注入SqlSessionFactory

1. 在applicationContext.xml中配置SqlSessionFactory

<?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"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://mybatis.org/schema/mybatis-spring http://mybatis.org/schema/mybatis-spring-1.2.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">

    <!-- 配置外部资源文件 -->
    <context:property-placeholder location="config/jdbc.properties" />

    <!-- 配置数据源 -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <property name="username" value="${username}"></property>
        <property name="password" value="${password}"></property>
        <property name="driverClassName" value="${driverClassName}"></property>
        <property name="url" value="${url}"></property>

        <property name="maxActive" value="30"></property>
        <property name="maxIdle" value="10"></property>
        <property name="minIdle" value="5"></property>
        <property name="maxWait" value="5000"></property>
    </bean>

    <!-- 配置会话工厂SqlSessionFactory -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 数据源 -->
        <property name="dataSource" ref="dataSource"></property>
        <!-- 加载SqlMapConfig.xml文件 -->
        <property name="configLocation" value="config/SqlMapConfig.xml"></property>
    </bean>

    <!-- 配置userDao -->
    <bean id="userDao" class="service.UserDaoImpl">
        <!-- 注入会话工厂SqlSessionFactory -->
        <property name="sqlSessionFactory" ref="sqlSessionFactory"></property>
    </bean>
</beans>

2. 编写Dao接口和Dao实现类

package service;

import bean.User;

public interface UserDao {
    //根据用户信息查询用户信息
    public User findUserById(Integer id);
}

package service;

import org.apache.ibatis.session.SqlSession;
import org.mybatis.spring.support.SqlSessionDaoSupport;

import bean.User;

public class UserDaoImpl extends SqlSessionDaoSupport implements UserDao {
    /**
     * 由于继承了SqlSessionDaoSupport类,该类有一个 
     * public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory)方法，
     * 所以可以通过Spring容器注入会话工厂
     */
    
    @Override
    public User findUserById(Integer id) {
        //从工厂中得到会话
        SqlSession sqlSession = this.getSqlSession();
        User user = sqlSession.selectOne("config.userMapper.getUser", 1);
        return user;
    }
}

3. userMapper.xml映射文件

<?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">

<!-- namespace:SQL映射文件所在的路路径 -->
<mapper namespace="config.userMapper">
    <!-- parameterType:参数id的值的类型 resultType:查询的结果返回的类型 -->
    <select id="getUser" parameterType="Integer" resultType="bean.User">
        select * from users where id=#{id}
    </select>
</mapper>

4. JUnit测试

package test;

import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import bean.User;
import service.UserDao;

public class SpringMybatisTest {
    private ApplicationContext applicationContext;

    @Before
    public void setUp() {
        // 构造Spring容器
        applicationContext = new ClassPathXmlApplicationContext(
                "config/applicationContext.xml");
    }

    @Test
    public void test() {
        UserDao userDao = (UserDao) applicationContext.getBean("userDao");
        User user = userDao.findUserById(1);
        System.out.println(user.getAge());
    }
}

• mapper动态代理整合方法：MyBatis使用动态代理的方法创建mapper对象，只需要程序员开发mapper接口(也就是Dao接口)和mapper映射文件，且mapper接口和mapper映射文件需要遵循一些规则：

      a. userMapper.xml的namespace是UserMapper.java的全限定名

       b. userMapper.xml中的statement的id值是UserMapper.java中的方法名，parameterTyep是方法的参数列表，resultType是方法的返回值。

然后在Spring容器中配置mapper扫描器，由扫描器扫描出mapper接口和mapper映射文件，从而动态的生成mapper接口的动态代理对象(mapperj接口的实现类对象)。产生的动态代理对象在Spring容器中自动注册，同时，一个扫描器可以扫描出多个mapper接口，可以生成多个

mapper接口的动态代理对象。

1. 在Spring容器中配置mapper扫描器(mapper扫描器类在整合包中)

applicationContext.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:context="http://www.springframework.org/schema/context"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://mybatis.org/schema/mybatis-spring http://mybatis.org/schema/mybatis-spring-1.2.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">

    <!-- 配置外部资源文件 -->
    <context:property-placeholder location="config/jdbc.properties" />

    <!-- 配置数据源 -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <property name="username" value="${username}"></property>
        <property name="password" value="${password}"></property>
        <property name="driverClassName" value="${driverClassName}"></property>
        <property name="url" value="${url}"></property>

        <property name="maxActive" value="30"></property>
        <property name="maxIdle" value="10"></property>
        <property name="minIdle" value="5"></property>
        <property name="maxWait" value="5000"></property>
    </bean>

    <!-- 配置会话工厂SqlSessionFactory -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 数据源 -->
        <property name="dataSource" ref="dataSource"></property>
        <!-- 加载SqlMapConfig.xml文件 -->
        <property name="configLocation" value="config/SqlMapConfig.xml"></property>
    </bean>
    
    <!-- Spring容器中配置mapper扫描器,
          由于产生的动态代理对象在Spring容器中自动注册,所以id默认值为mapper接口名(首字母小写) -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- 指定扫描包的路径，就是mapper接口的路径 -->
        <property name="basePackage" value="service"></property>
        <!-- 配置sqlSessionFactoryBeanName,也就是配置会话工厂 -->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>
    </bean>
</beans>

2. UserMapper.java类

package service;

import bean.User;

public interface UserMapper {
    //根据用户信息查询用户信息
    public User findUserById(Integer id);
}

3. userMpper.xml映射文件

<?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">

<!-- namespace:UserMapper.java的全限定名 -->
<mapper namespace="service.UserMapper">
    <!—id是UserMapper.java接口中方法名，parameterTyep：UserMapper.java接口中方法的参数类型，resultType：方法的返回值类型-->
    <select id="findUserById" parameterType="Integer" resultType="bean.User">
        select * from users where id=#{id}
    </select>
</mapper>

4. JUnit测试

package test;

import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import bean.User;
import service.UserDao;
import service.UserMapper;

public class SpringMybatisTest {
    private ApplicationContext applicationContext;

    @Before
    public void setUp() {
        // 构造Spring容器
        applicationContext = new ClassPathXmlApplicationContext(
                "config/applicationContext.xml");
    }

    @Test
    public void testFindUserById(){
        //从Spring容器中获取mapper动态代理对象
        UserMapper userMapper = (UserMapper) applicationContext.getBean("userMapper");
        User user = userMapper.findUserById(1);
        System.out.println(user.getName());
    }
}