Spring扫描Mybatis的mapper接口的三种配置方式

mybatis支持与spring结合使用，使得mybatis中的mapper接口可以作为spring容器中的bean被应用代码中相关类，如Service类，通过@Autowired自动注入进来。在使用方面需要在项目中引入以下包：
```
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis-spring</artifactId>
    <version>1.3.1</version>
</dependency>
```
在spring中可以通过三种方式来自动扫描获取应用代码的mybatis相关的mapper接口定义：

在applicationContext.xml中使用<mybatis:scan />

<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:context="http://www.springframework.org/schema/context"
   xmlns:tx="http://www.springframework.org/schema/tx"
   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-3.0.xsd
   http://www.springframework.org/schema/context 
   http://www.springframework.org/schema/context/spring-context-3.0.xsd
   http://www.springframework.org/schema/tx
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">
   
   ...
   
    <!-- mybatis -->
   <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
   		<property name="dataSource" ref="dataSource" />
   		<property name="mapperLocations" value="classpath:mybatis/mapper/**/*.xml" />
   		<property name="configLocation" value="classpath:mybatis/mybitas-config.xml" />
   </bean>
   
   <mybatis:scan base-package="org.xyz.jblog.dao"/>
   
   ...
   
</beans>

在applicationContext.xml中使用bean标签注册MapperScannerConfigurer，即

<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:context="http://www.springframework.org/schema/context"
   xmlns:tx="http://www.springframework.org/schema/tx"
   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-3.0.xsd
   http://www.springframework.org/schema/context 
   http://www.springframework.org/schema/context/spring-context-3.0.xsd
   http://www.springframework.org/schema/tx
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">
   
   ...
   
    <!-- mybatis -->
   <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
   		<property name="dataSource" ref="dataSource" />
   		<property name="mapperLocations" value="classpath:mybatis/mapper/**/*.xml" />
   		<property name="configLocation" value="classpath:mybatis/mybitas-config.xml" />
   </bean>
   
   <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
   		<property name="basePackage" value="org.xyz.jblog.dao" />
   </bean>
   
   ...
   
</beans>

如果应用是使用Java配置方式而不是XML，则在@Configuration配置类使用@MapperScan或者@MapperScans注解：

@Configuration
@MapperScan("org.xyz.jblog.dao")
public class AppConfig {
    @Bean
    public DataSource dataSource() {
        return new PooledDataSource("com.mysql.jdbc.Driver", "jdbc:mysql://localhost:3306/test", "root", "root");
    }
    @Bean
    public SqlSessionFactory sqlSessionFactory() throws Exception {
        SqlSessionFactoryBeansessionFactory = new SqlSessionFactoryBean();
        sessionFactory.setDataSource(dataSource());
        return sessionFactory.getObject();
    }
}