Mybatis作为一个优秀的存储过程和高级映射的持久层框架,目前在项目实践中运用的比较广泛,最近做项目时候发现了一种之前没见过的配置方式,这里总结下常用的配置方式以便备忘查找。
(1)数据源配置 <bean id="dataSourceForA" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close"> <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" /> <property name="url" value="${db1_url}" /> <property name="username" value="$db1_user}" /> <property name="password" value="${db1_passwd}" /> <property name="maxWait" value="${db1_maxWait}" /> <property name="maxActive" value="28" /> <property name="initialSize" value="2" /> <property name="minIdle" value="0" /> <property name="timeBetweenEvictionRunsMillis" value="300000" /> <property name="testOnBorrow" value="false" /> <property name="testWhileIdle" value="true" /> <property name="validationQuery" value="select 1 from dual" /> <property name="filters" value="stat" /> </bean> (2)创建sqlSessionFactory <bean id="sqlSessionFactoryForA" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="mapperLocations" value="classpath*:com/**/mapper1/*Mapper*.xml" /> <property name="dataSource" ref="dataSourceForA" /> <property name="typeAliasesPackage" value="com.zlx.***.dal" /> </bean> (3)配置扫描器,扫描指定路径的mapper生成数据库操作代理类 <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="annotationClass" value="javax.annotation.Resource"></property> <property name="basePackage" value="com.zlx1.***.dal.***.mapper" /> <property name="sqlSessionFactory" ref="sqlSessionFactoryForA" /> </bean> (4)数据源配置 <bean id="dataSourceForB" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close"> <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" /> <property name="url" value="${db_url}" /> <property name="username" value="$db_user}" /> <property name="password" value="${db_passwd}" /> <property name="maxWait" value="${db_maxWait}" /> <property name="maxActive" value="28" /> <property name="initialSize" value="2" /> <property name="minIdle" value="0" /> <property name="timeBetweenEvictionRunsMillis" value="300000" /> <property name="testOnBorrow" value="false" /> <property name="testWhileIdle" value="true" /> <property name="validationQuery" value="select 1 from dual" /> <property name="filters" value="stat" /> </bean> (5)创建sqlSessionFactory <bean id="sqlSessionFactoryForB" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="mapperLocations" value="classpath*:com/**/mapper/*Mapper*.xml" /> <property name="dataSource" ref="dataSourceForB" /> <property name="typeAliasesPackage" value="com.zlx.***.dal" /> </bean> (6)配置扫描器,扫描指定路径的mapper生成数据库操作代理类 <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="annotationClass" value="javax.annotation.Resource"></property> <property name="basePackage" value="com.zlx.***.dal.***.mapper" /> <property name="sqlSessionFactory" ref="sqlSessionFactoryForB" /> </bean>
(2)(5)作用是根据配置创建一个SqlSessionFactory,看下SqlSessionFactoryBean的代码知道它实现了FactoryBean和InitializingBean类,由于实现了InitializingBean,所以自然它的afterPropertiesSet方法,由于实现了FactoryBean类,所以自然会有getObject方法。下面看下时序图:
从时序图可知,SqlSessionFactoryBean类主要是通过属性配置创建SqlSessionFactory实例,具体是解析配置中所有的mapper文件放到configuration,然后作为构造函数参数实例化一个DefaultSqlSessionFactory作为SqlSessionFactory。
扫描指定路径的mapper生成数据库操作代理类
MapperScannerConfigurer 实现了 BeanDefinitionRegistryPostProcessor, InitializingBean, ApplicationContextAware, BeanNameAware接口,所以会重写一下方法:
//在bean注册到ioc后创建实例前修改bean定义和新增bean注册,这个是在context的refresh方法调用 void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException; //在bean注册到ioc后创建实例前修改bean定义或者属性值 void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException; //set属性设置后调用 void afterPropertiesSet() throws Exception; //获取IOC容器上下文,在context的prepareBeanFactory中调用 void setApplicationContext(ApplicationContext applicationContext) throws BeansException; //获取bean在ioc容器中名字,在context的prepareBeanFactory中调用 void setBeanName(String name);
先上个扫描mapper生成代理类并注册到ioc时序图:
首先MapperScannerConfigurer实现的afterPropertiesSet方法用来确保属性basePackage不为空
public void afterPropertiesSet() throws Exception { notNull(this.basePackage, "Property 'basePackage' is required"); }
postProcessBeanFactory里面啥都没做,setBeanName获取了bean的名字,setApplicationContext里面获取了ioc上下文。下面看重要的方法postProcessBeanDefinitionRegistry,由于mybais是运行时候才通过解析mapper文件生成代理类注入到ioc,所以postProcessBeanDefinitionRegistry正好可以干这个事情。
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) { if (this.processPropertyPlaceHolders) { processPropertyPlaceHolders(); } //构造一个ClassPathMapperScanner查找mapper ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry); scanner.setAddToConfig(this.addToConfig); //javax.annotation.Resource scanner.setAnnotationClass(this.annotationClass); scanner.setMarkerInterface(this.markerInterface); //引用sqlSessionFactory scanner.setSqlSessionFactory(this.sqlSessionFactory); scanner.setSqlSessionTemplate(this.sqlSessionTemplate); scanner.setSqlSessionFactoryBeanName(this.sqlSessionFactoryBeanName); scanner.setSqlSessionTemplateBeanName(this.sqlSessionTemplateBeanName); //ioc上下文 scanner.setResourceLoader(this.applicationContext); scanner.setBeanNameGenerator(this.nameGenerator); scanner.registerFilters(); //basePackage=com.alibaba.***.dal.***.mapper,com.alibaba.rock.auth.mapper,com.alibaba.rock.workflow.dal.workflow.mapper scanner.scan(StringUtils.tokenizeToStringArray(this.basePackage, ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS)); }
下面重点看下scan方法:
public Set<BeanDefinitionHolder> doScan(String... basePackages) { //根据指定路径去查找对应mapper的接口类,并转化为beandefination Set<BeanDefinitionHolder> beanDefinitions = super.doScan(basePackages); if (beanDefinitions.isEmpty()) { logger.warn("No MyBatis mapper was found in '" + Arrays.toString(basePackages) + "' package. Please check your configuration."); } else { //修改接口类bean的beandefination processBeanDefinitions(beanDefinitions); } return beanDefinitions; }
其中super.doScan(basePackages);根据指定路径查找mapper接口类,并生成bean的定义对象,对象中包含beanclassname,beanclass属性,最后注册该bean到ioc容器。下面看下最重要的processBeanDefinitions方法对bean定义的改造。
private void processBeanDefinitions(Set<BeanDefinitionHolder> beanDefinitions) { GenericBeanDefinition definition; for (BeanDefinitionHolder holder : beanDefinitions) { definition = (GenericBeanDefinition) holder.getBeanDefinition(); // 上面讲的扫描后beanclass设置的为mapper接口类,但是这里修改为MapperFactoryBean,MapperFactoryBean代理了mapper接口类,并且实际mapper接口类作为构造函数传入了 definition.getConstructorArgumentValues().addGenericArgumentValue(definition.getBeanClassName()); definition.setBeanClass(this.mapperFactoryBean.getClass()); definition.getPropertyValues().add("addToConfig", this.addToConfig); //设置属性配置中的sqlSessionFactory boolean explicitFactoryUsed = false; if (StringUtils.hasText(this.sqlSessionFactoryBeanName)) { definition.getPropertyValues().add("sqlSessionFactory", new RuntimeBeanReference(this.sqlSessionFactoryBeanName)); explicitFactoryUsed = true; } else if (this.sqlSessionFactory != null) { definition.getPropertyValues().add("sqlSessionFactory", this.sqlSessionFactory); explicitFactoryUsed = true; } if (StringUtils.hasText(this.sqlSessionTemplateBeanName)) { if (explicitFactoryUsed) { logger.warn("Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored."); } definition.getPropertyValues().add("sqlSessionTemplate", new RuntimeBeanReference(this.sqlSessionTemplateBeanName)); explicitFactoryUsed = true; } else if (this.sqlSessionTemplate != null) { if (explicitFactoryUsed) { logger.warn("Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored."); } definition.getPropertyValues().add("sqlSessionTemplate", this.sqlSessionTemplate); explicitFactoryUsed = true; } if (!explicitFactoryUsed) { if (logger.isDebugEnabled()) { logger.debug("Enabling autowire by type for MapperFactoryBean with name '" + holder.getBeanName() + "'."); } definition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE); } } }
注:这里修改了mapper接口类的beandefination中的beanclass为MapperFactoryBean,它则负责生产数据类操作代理类,实际mapper接口类作为构造函数传入了 。由于只修改了beanclass,没有修改beanname,所以我们从容器中获取时候无感知的。
在上一个代理bean如何构造的时序图:
下面看下MapperFactoryBean是如何生成代理类的:
首先,上面代码设置了MapperFactoryBean的setSqlSessionFactory方法:
public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) { if (!this.externalSqlSession) { this.sqlSession = new SqlSessionTemplate(sqlSessionFactory); } }
上面方法创建了sqlSession,由于MapperFactoryBean为工厂bean所以实例化时候会调用getObject方法:
public T getObject() throws Exception { return getSqlSession().getMapper(this.mapperInterface); }
其实是调用了SqlSessionTemplate->getMapper,其中mapperInterface就是创建MapperFactoryBean时候的构造函数参数。
public <T> T getMapper(Class<T> type) { return getConfiguration().getMapper(type, this); }
这里调用getConfiguration().getMapper(type, this);实际是DefaultSqlSessionFactory里面的configration的getMapper方法:
public <T> T getMapper(Class<T> type, SqlSession sqlSession) { //knownMappers是上面时序图中步骤6设置进入的。 final MapperProxyFactory<T> mapperProxyFactory = (MapperProxyFactory<T>) knownMappers.get(type); if (mapperProxyFactory == null) { throw new BindingException("Type " + type + " is not known to the MapperRegistry."); } try { return mapperProxyFactory.newInstance(sqlSession); } catch (Exception e) { throw new BindingException("Error getting mapper instance. Cause: " + e, e); } } protected T newInstance(MapperProxy<T> mapperProxy) { return (T) Proxy.newProxyInstance(mapperInterface.getClassLoader(), new Class[] { mapperInterface }, mapperProxy); } public T newInstance(SqlSession sqlSession) { //代理回调类为MapperProxy final MapperProxy<T> mapperProxy = new MapperProxy<T>(sqlSession, mapperInterface, methodCache); return newInstance(mapperProxy); }
在上一个实际执行sql时候调用代理类的序列图:
所以当调用实际的数据库操作时候会调用MapperProxy的invoke方法:
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { if (Object.class.equals(method.getDeclaringClass())) { try { return method.invoke(this, args); } catch (Throwable t) { throw ExceptionUtil.unwrapThrowable(t); } } final MapperMethod mapperMethod = cachedMapperMethod(method); return mapperMethod.execute(sqlSession, args); }
mapperMethod.execute(sqlSession, args);里面实际是调用当前mapper对应的SqlSessionTemplate的数据库操作,而它有委托给了代理类sqlSessionProxy,sqlSessionProxy是在SqlSessionTemplate的构造函数里面创建的:
public SqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType, PersistenceExceptionTranslator exceptionTranslator) { notNull(sqlSessionFactory, "Property 'sqlSessionFactory' is required"); notNull(executorType, "Property 'executorType' is required"); this.sqlSessionFactory = sqlSessionFactory; this.executorType = executorType; this.exceptionTranslator = exceptionTranslator; this.sqlSessionProxy = (SqlSession) newProxyInstance( SqlSessionFactory.class.getClassLoader(), new Class[] { SqlSession.class }, new SqlSessionInterceptor()); }
所以最终数据库操作有被代理SqlSessionInterceptor执行:
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { //有TransactionSynchronizationManager管理 SqlSession sqlSession = getSqlSession( SqlSessionTemplate.this.sqlSessionFactory, SqlSessionTemplate.this.executorType, SqlSessionTemplate.this.exceptionTranslator); try { Object result = method.invoke(sqlSession, args); if (!isSqlSessionTransactional(sqlSession, SqlSessionTemplate.this.sqlSessionFactory)) { // force commit even on non-dirty sessions because some databases require // a commit/rollback before calling close() sqlSession.commit(true); } return result; } catch (Throwable t) { ..... } } public static SqlSession getSqlSession(SqlSessionFactory sessionFactory, ExecutorType executorType, PersistenceExceptionTranslator exceptionTranslator) { notNull(sessionFactory, NO_SQL_SESSION_FACTORY_SPECIFIED); notNull(executorType, NO_EXECUTOR_TYPE_SPECIFIED); SqlSessionHolder holder = (SqlSessionHolder) TransactionSynchronizationManager.getResource(sessionFactory); SqlSession session = sessionHolder(executorType, holder); if (session != null) { return session; } if (LOGGER.isDebugEnabled()) { LOGGER.debug("Creating a new SqlSession"); } //这里看到了使用sessionfactory熟悉的打开了一个session session = sessionFactory.openSession(executorType); registerSessionHolder(sessionFactory, executorType, exceptionTranslator, session); return session; }
关于事务配置可移步:http://www.jianshu.com/p/1d882343c036
(1)数据源配置 <bean id="dataSourceForA" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close"> <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" /> <property name="url" value="${db1_url}" /> <property name="username" value="$db1_user}" /> <property name="password" value="${db1_passwd}" /> <property name="maxWait" value="${db1_maxWait}" /> <property name="maxActive" value="28" /> <property name="initialSize" value="2" /> <property name="minIdle" value="0" /> <property name="timeBetweenEvictionRunsMillis" value="300000" /> <property name="testOnBorrow" value="false" /> <property name="testWhileIdle" value="true" /> <property name="validationQuery" value="select 1 from dual" /> <property name="filters" value="stat" /> </bean> (2)创建sqlSessionFactory <bean id="sqlSessionFactoryForA" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="mapperLocations" value="classpath*:com/**/mapper1/*Mapper*.xml" /> <property name="dataSource" ref="dataSourceForA" /> <property name="typeAliasesPackage" value="com.zlx.***.dal" /> </bean> (3)配置扫描器,扫描指定路径的mapper生成数据库操作代理类 <mybatis:scan base-package="com.zlx1.***.dal" factory-ref="sqlSessionFactoryForA" annotation="javax.annotation.Resource"/> (4)数据源配置 <bean id="dataSourceForB" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close"> <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" /> <property name="url" value="${db_url}" /> <property name="username" value="$db_user}" /> <property name="password" value="${db_passwd}" /> <property name="maxWait" value="${db_maxWait}" /> <property name="maxActive" value="28" /> <property name="initialSize" value="2" /> <property name="minIdle" value="0" /> <property name="timeBetweenEvictionRunsMillis" value="300000" /> <property name="testOnBorrow" value="false" /> <property name="testWhileIdle" value="true" /> <property name="validationQuery" value="select 1 from dual" /> <property name="filters" value="stat" /> </bean> (5)创建sqlSessionFactory <bean id="sqlSessionFactoryForB" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="mapperLocations" value="classpath*:com/**/mapper/*Mapper*.xml" /> <property name="dataSource" ref="dataSourceForB" /> <property name="typeAliasesPackage" value="com.zlx.***.dal" /> </bean> (6)配置扫描器,扫描指定路径的mapper生成数据库操作代理类 <mybatis:scan base-package="com.zlx.***.dal" factory-ref="sqlSessionFactoryForB" annotation="javax.annotation.Resource"/>
与上节不同在在于(3)(6)
这里只看 <mybatis:scan/> 标签解析,按照惯例看jar包的spring.handler找标签解析
 MapperScannerBeanDefinitionParser的代码如下:
可知MapperScannerBeanDefinitionParser所做的事情和MapperScannerConfigurer类似都是内部搞了个ClassPathMapperScanner。
数据源一配置:
//三、设置扫描器 @MapperScan(basePackages = "com.alibaba.zlx.web.speech.mapper",sqlSessionFactoryRef="sqlSessionFactory1") public class TddlAutoConfiguration { @Autowired private TddlProperties properties; //一、创建数据源 @Primary @Bean(name = "dataSource1") public DataSource dataSource1() throws TddlException { TDataSource dataSource = new TDataSource(); dataSource.setAppName(properties.getAppName()); dataSource.setSharding(properties.getSharding()); dataSource.setDynamicRule(properties.getDynamicRule()); dataSource.init(); return dataSource; } //二、创建SqlSessionFactory @Bean(name = "sqlSessionFactory1") @Primary public SqlSessionFactory sqlSessionFactoryBean1() throws Exception { SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean(); sqlSessionFactoryBean.setDataSource(dataSource1()); sqlSessionFactoryBean.setMapperLocations(resolveMapperLocations(new String[]{"classpath:mapper/*.xml"})); return sqlSessionFactoryBean.getObject(); } //四、 创建事务管理器 @Bean(name = "txManager1") @Primary public PlatformTransactionManager txManager1(@Qualifier("dataSource1")DataSource dataSource) { System.out.println("-----------dataource-----" + dataSource.toString()); return new DataSourceTransactionManager(dataSource); } @Bean("sqlSessionTemplate1") @Primary public SqlSessionTemplate sqlSessionTemplate(@Qualifier("sqlSessionFactory1")SqlSessionFactory sqlSessionFactory) { System.out.println("-----------sqlSessionFactory-----" + sqlSessionFactory.toString()); return new SqlSessionTemplate(sqlSessionFactory); } }
数据源二配置:
//三、设置扫描器 @MapperScan(basePackages = "com.alibaba.gh.web.speech.mapper", sqlSessionFactoryRef = "sqlSessionFactory2") public class TddlAutoConfiguration2 { @Autowired private TddlProperties properties; //一、创建数据源 @Bean(name = "dataSource2") public DataSource dataSource2() throws TddlException { TDataSource dataSource = new TDataSource(); dataSource.setAppName(properties.getAppName()); dataSource.setSharding(properties.getSharding()); dataSource.setDynamicRule(properties.getDynamicRule()); dataSource.init(); return dataSource; } //二、创建SqlSessionFactory @Bean(name = "sqlSessionFactory2") public SqlSessionFactory sqlSessionFactoryBean1() throws Exception { SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean(); sqlSessionFactoryBean.setDataSource(dataSource2()); sqlSessionFactoryBean.setMapperLocations(resolveMapperLocations(new String[] { "classpath:mapper2/*.xml" })); return sqlSessionFactoryBean.getObject(); } // 四、创建事务管理器 @Bean(name = "txManager2") public PlatformTransactionManager txManager1(@Qualifier("dataSource2") DataSource dataSource) { System.out.println("-----------dataource-----" + dataSource.toString()); return new DataSourceTransactionManager(dataSource); } @Bean("sqlSessionTemplate2") public SqlSessionTemplate sqlSessionTemplate(@Qualifier("sqlSessionFactory2")SqlSessionFactory sqlSessionFactory) { System.out.println("-----------sqlSessionFactory-----" + sqlSessionFactory.toString()); return new SqlSessionTemplate(sqlSessionFactory); } }
另外SqlSessionTemplate是对SqlSessionFactory的一个包装,这里每个数据源也配置了一个,如果想使用它的话,只需要修改@mapperscan,设置sqlSessionTemplateRef替换sqlSessionFactoryRef。