mybatis 个别集成到spring框架中应用，上面介绍如何在spring中应用mybatis

  1. 创立datasource实例

     <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">     <property name="driverClassName">         <value>com.mysql.jdbc.Driver</value>     </property>     <property name="url">         <value>jdbc:mysql://localhost:3306/test?characterEncoding=UTF-8</value>     </property>     <property name="username">         <value>root</value>     </property>     <property name="password">         <value>xxx</value>     </property> </bean>

  2. 创立SqlSessionFactoryBean 实例

     <bean id="sqlSession" class="org.mybatis.spring.SqlSessionFactoryBean">     <property name="dataSource" ref="dataSource"/>     <property name="plugins">         <array>             <bean class="com.learn.springmybatis.ExecutorInterceptor"></bean>         </array>     </property> </bean>

  3. 创立数据库操作的bean

     <bean id="userDao" class="org.mybatis.spring.mapper.MapperFactoryBean">     <property name="mapperInterface" value="com.learn.springmybatis.UserDao"/>     <property name="sqlSessionFactory" ref="sqlSession"></property> </bean>

    当然还有具体java代码，这里不体现进去。列出上述配置次要阐明mybatis应用的大体流程。业务代码最终是拿数据库操作bean实例，如userDao去操作数据库。那咱们就从userDao开始吧，看看业务代码通过mybatis是如何和db打交道的。

userDao的实例化过程

上面是UserDao的java代码，一个Interface，外面除了有一个注解，啥都没有。那么它是如何实现数据插入的呢？

public interface UserDao {    @Insert(" insert into user ( id, name, title ) values (#{id},#{name}, #{title}) ")    public int insert(User user);}

  • userDao是MapperFactoryBean创立的
    从xml配置咱们能够得悉，userDao是MapperFactoryBean创立，而MapperFactoryBean实现类FactoryBean接口，Spring的FactoryBean能够依据须要创立不同类型的bean

    通过MapperFactoryBean的getObject获取userDao实例

      public T getObject() throws Exception {      return this.getSqlSession().getMapper(this.mapperInterface);  }

    this.getSqlSession()是new SqlSessionTemplate(sqlSessionFactory)
    最终进入Configuration的getMapper

      public <T> T getMapper(Class<T> type, SqlSession sqlSession) {      return this.mapperRegistry.getMapper(type, sqlSession);  }

    最终调用到MapperRegistry，具体代码如下，通过type在knownMappers获取mapperProxyFactory，这里间接用knownMappers，那么这个knownMapper什么时候初始化好的？先留个疑难，不焦急解答。获取到mapperProxyFactory后创立新的实例

      public <T> T getMapper(Class<T> type, SqlSession sqlSession) {      MapperProxyFactory<T> mapperProxyFactory = (MapperProxyFactory)this.knownMappers.get(type);      if (mapperProxyFactory == null) {          throw new BindingException("Type " + type + " is not known to the MapperRegistry.");      } else {          try {              return mapperProxyFactory.newInstance(sqlSession);          } catch (Exception var5) {              throw new BindingException("Error getting mapper instance. Cause: " + var5, var5);          }      }  }

    新实例如何创立？看代码，用到java的动静代理,sql的执行，最终会代理到这个MapperProxy进行，想晓得sql如何执行，只需剖析MapperProxy即可。

      protected T newInstance(MapperProxy<T> mapperProxy) {      return Proxy.newProxyInstance(this.mapperInterface.getClassLoader(), new Class[]{this.mapperInterface}, mapperProxy);  }  public T newInstance(SqlSession sqlSession) {      MapperProxy<T> mapperProxy = new MapperProxy(sqlSession, this.mapperInterface, this.methodCache);      return this.newInstance(mapperProxy);  }
  • 未完待续