您好,登錄后才能下訂單哦!
一、摘要
這篇文章將介紹Spring整合Mybatis 如何完成SqlSessionFactory的動(dòng)態(tài)切換的。并且會(huì)簡(jiǎn)單的介紹下MyBatis整合Spring中的官方的相關(guān)代碼。
Spring整合MyBatis切換SqlSessionFactory有兩種方法
第一、 繼承SqlSessionDaoSupport,重寫(xiě)獲取SqlSessionFactory的方法。
第二、繼承SqlSessionTemplate 重寫(xiě)getSqlSessionFactory、getConfiguration和SqlSessionInterceptor這個(gè)攔截器。其中最為關(guān)鍵還是繼承SqlSessionTemplate 并重寫(xiě)里面的方法。
而Spring整合MyBatis也有兩種方式,一種是配置MapperFactoryBean,另一種則是利用MapperScannerConfigurer進(jìn)行掃描接口或包完成對(duì)象的自動(dòng)創(chuàng)建。相對(duì)來(lái)說(shuō)后者更方便些。
MapperFactoryBean繼承了SqlSessionDaoSupport也就是動(dòng)態(tài)切換SqlSessionFactory的第一種方法,我們需要重寫(xiě)和實(shí)現(xiàn)SqlSessionDaoSupport方法,或者是繼承MapperFactoryBean來(lái)重寫(xiě)覆蓋相關(guān)方法。如果利用MapperScannerConfigurer的配置整合來(lái)切換SqlSessionFactory,那么我們就需要繼承SqlSessionTemplate,重寫(xiě)上面提到的方法。在整合的配置中很多地方都是可以注入SqlSessionTemplate代替SqlSessionFactory的注入的。因?yàn)镾qlSessionTemplate的創(chuàng)建也是需要注入SqlSessionFactory的。
二、實(shí)現(xiàn)代碼
1、繼承SqlSessionTemplate 重寫(xiě)getSqlSessionFactory、getConfiguration和SqlSessionInterceptor
package com.hoo.framework.mybatis.support; import static java.lang.reflect.Proxy.newProxyInstance; import static org.apache.ibatis.reflection.ExceptionUtil.unwrapThrowable; import static org.mybatis.spring.SqlSessionUtils.closeSqlSession; import static org.mybatis.spring.SqlSessionUtils.getSqlSession; import static org.mybatis.spring.SqlSessionUtils.isSqlSessionTransactional; import java.lang.reflect.InvocationHandler; import java.lang.reflect.Method; import java.sql.Connection; import java.util.List; import java.util.Map; import org.apache.ibatis.exceptions.PersistenceException; import org.apache.ibatis.executor.BatchResult; import org.apache.ibatis.session.Configuration; import org.apache.ibatis.session.ExecutorType; import org.apache.ibatis.session.ResultHandler; import org.apache.ibatis.session.RowBounds; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.mybatis.spring.MyBatisExceptionTranslator; import org.mybatis.spring.SqlSessionTemplate; import org.springframework.dao.support.PersistenceExceptionTranslator; import org.springframework.util.Assert; /** * <b>function:</b> 繼承SqlSessionTemplate 重寫(xiě)相關(guān)方法 * @author hoojo * @createDate 2013-10-18 下午03:07:46 * @file CustomSqlSessionTemplate.java * @package com.hoo.framework.mybatis.support * @project SHMB * @blog http://blog.csdn.net/IBM_hoojo * @email hoojo_@126.com * @version 1.0 */ public class CustomSqlSessionTemplate extends SqlSessionTemplate { private final SqlSessionFactory sqlSessionFactory; private final ExecutorType executorType; private final SqlSession sqlSessionProxy; private final PersistenceExceptionTranslator exceptionTranslator; private Map<Object, SqlSessionFactory> targetSqlSessionFactorys; private SqlSessionFactory defaultTargetSqlSessionFactory; public void setTargetSqlSessionFactorys(Map<Object, SqlSessionFactory> targetSqlSessionFactorys) { this.targetSqlSessionFactorys = targetSqlSessionFactorys; } public void setDefaultTargetSqlSessionFactory(SqlSessionFactory defaultTargetSqlSessionFactory) { this.defaultTargetSqlSessionFactory = defaultTargetSqlSessionFactory; } public CustomSqlSessionTemplate(SqlSessionFactory sqlSessionFactory) { this(sqlSessionFactory, sqlSessionFactory.getConfiguration().getDefaultExecutorType()); } public CustomSqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType) { this(sqlSessionFactory, executorType, new MyBatisExceptionTranslator(sqlSessionFactory.getConfiguration() .getEnvironment().getDataSource(), true)); } public CustomSqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType, PersistenceExceptionTranslator exceptionTranslator) { super(sqlSessionFactory, executorType, exceptionTranslator); this.sqlSessionFactory = sqlSessionFactory; this.executorType = executorType; this.exceptionTranslator = exceptionTranslator; this.sqlSessionProxy = (SqlSession) newProxyInstance( SqlSessionFactory.class.getClassLoader(), new Class[] { SqlSession.class }, new SqlSessionInterceptor()); this.defaultTargetSqlSessionFactory = sqlSessionFactory; } @Override public SqlSessionFactory getSqlSessionFactory() { SqlSessionFactory targetSqlSessionFactory = targetSqlSessionFactorys.get(CustomerContextHolder.getContextType()); if (targetSqlSessionFactory != null) { return targetSqlSessionFactory; } else if (defaultTargetSqlSessionFactory != null) { return defaultTargetSqlSessionFactory; } else { Assert.notNull(targetSqlSessionFactorys, "Property 'targetSqlSessionFactorys' or 'defaultTargetSqlSessionFactory' are required"); Assert.notNull(defaultTargetSqlSessionFactory, "Property 'defaultTargetSqlSessionFactory' or 'targetSqlSessionFactorys' are required"); } return this.sqlSessionFactory; } @Override public Configuration getConfiguration() { return this.getSqlSessionFactory().getConfiguration(); } public ExecutorType getExecutorType() { return this.executorType; } public PersistenceExceptionTranslator getPersistenceExceptionTranslator() { return this.exceptionTranslator; } /** * {@inheritDoc} */ public <T> T selectOne(String statement) { return this.sqlSessionProxy.<T> selectOne(statement); } /** * {@inheritDoc} */ public <T> T selectOne(String statement, Object parameter) { return this.sqlSessionProxy.<T> selectOne(statement, parameter); } /** * {@inheritDoc} */ public <K, V> Map<K, V> selectMap(String statement, String mapKey) { return this.sqlSessionProxy.<K, V> selectMap(statement, mapKey); } /** * {@inheritDoc} */ public <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey) { return this.sqlSessionProxy.<K, V> selectMap(statement, parameter, mapKey); } /** * {@inheritDoc} */ public <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey, RowBounds rowBounds) { return this.sqlSessionProxy.<K, V> selectMap(statement, parameter, mapKey, rowBounds); } /** * {@inheritDoc} */ public <E> List<E> selectList(String statement) { return this.sqlSessionProxy.<E> selectList(statement); } /** * {@inheritDoc} */ public <E> List<E> selectList(String statement, Object parameter) { return this.sqlSessionProxy.<E> selectList(statement, parameter); } /** * {@inheritDoc} */ public <E> List<E> selectList(String statement, Object parameter, RowBounds rowBounds) { return this.sqlSessionProxy.<E> selectList(statement, parameter, rowBounds); } /** * {@inheritDoc} */ public void select(String statement, ResultHandler handler) { this.sqlSessionProxy.select(statement, handler); } /** * {@inheritDoc} */ public void select(String statement, Object parameter, ResultHandler handler) { this.sqlSessionProxy.select(statement, parameter, handler); } /** * {@inheritDoc} */ public void select(String statement, Object parameter, RowBounds rowBounds, ResultHandler handler) { this.sqlSessionProxy.select(statement, parameter, rowBounds, handler); } /** * {@inheritDoc} */ public int insert(String statement) { return this.sqlSessionProxy.insert(statement); } /** * {@inheritDoc} */ public int insert(String statement, Object parameter) { return this.sqlSessionProxy.insert(statement, parameter); } /** * {@inheritDoc} */ public int update(String statement) { return this.sqlSessionProxy.update(statement); } /** * {@inheritDoc} */ public int update(String statement, Object parameter) { return this.sqlSessionProxy.update(statement, parameter); } /** * {@inheritDoc} */ public int delete(String statement) { return this.sqlSessionProxy.delete(statement); } /** * {@inheritDoc} */ public int delete(String statement, Object parameter) { return this.sqlSessionProxy.delete(statement, parameter); } /** * {@inheritDoc} */ public <T> T getMapper(Class<T> type) { return getConfiguration().getMapper(type, this); } /** * {@inheritDoc} */ public void commit() { throw new UnsupportedOperationException("Manual commit is not allowed over a Spring managed SqlSession"); } /** * {@inheritDoc} */ public void commit(boolean force) { throw new UnsupportedOperationException("Manual commit is not allowed over a Spring managed SqlSession"); } /** * {@inheritDoc} */ public void rollback() { throw new UnsupportedOperationException("Manual rollback is not allowed over a Spring managed SqlSession"); } /** * {@inheritDoc} */ public void rollback(boolean force) { throw new UnsupportedOperationException("Manual rollback is not allowed over a Spring managed SqlSession"); } /** * {@inheritDoc} */ public void close() { throw new UnsupportedOperationException("Manual close is not allowed over a Spring managed SqlSession"); } /** * {@inheritDoc} */ public void clearCache() { this.sqlSessionProxy.clearCache(); } /** * {@inheritDoc} */ public Connection getConnection() { return this.sqlSessionProxy.getConnection(); } /** * {@inheritDoc} * @since 1.0.2 */ public List<BatchResult> flushStatements() { return this.sqlSessionProxy.flushStatements(); } /** * Proxy needed to route MyBatis method calls to the proper SqlSession got from Spring's Transaction Manager It also * unwraps exceptions thrown by {@code Method#invoke(Object, Object...)} to pass a {@code PersistenceException} to * the {@code PersistenceExceptionTranslator}. */ private class SqlSessionInterceptor implements InvocationHandler { public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { final SqlSession sqlSession = getSqlSession( CustomSqlSessionTemplate.this.getSqlSessionFactory(), CustomSqlSessionTemplate.this.executorType, CustomSqlSessionTemplate.this.exceptionTranslator); try { Object result = method.invoke(sqlSession, args); if (!isSqlSessionTransactional(sqlSession, CustomSqlSessionTemplate.this.getSqlSessionFactory())) { // 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) { Throwable unwrapped = unwrapThrowable(t); if (CustomSqlSessionTemplate.this.exceptionTranslator != null && unwrapped instanceof PersistenceException) { Throwable translated = CustomSqlSessionTemplate.this.exceptionTranslator .translateExceptionIfPossible((PersistenceException) unwrapped); if (translated != null) { unwrapped = translated; } } throw unwrapped; } finally { closeSqlSession(sqlSession, CustomSqlSessionTemplate.this.getSqlSessionFactory()); } } } }
重寫(xiě)后的getSqlSessionFactory方法會(huì)從我們配置的SqlSessionFactory集合targetSqlSessionFactorys或默認(rèn)的defaultTargetSqlSessionFactory中獲取Session對(duì)象。而改寫(xiě)的SqlSessionInterceptor 是這個(gè)MyBatis整合Spring的關(guān)鍵,所有的SqlSessionFactory對(duì)象的session都將在這里完成創(chuàng)建、提交、關(guān)閉等操作。所以我們改寫(xiě)這里的代碼,在這里獲取getSqlSessionFactory的時(shí)候,從多個(gè)SqlSessionFactory中獲取我們?cè)O(shè)置的那個(gè)即可。
上面添加了targetSqlSessionFactorys、defaultTargetSqlSessionFactory兩個(gè)屬性來(lái)配置多個(gè)SqlSessionFactory對(duì)象和默認(rèn)的SqlSessionFactory對(duì)象。
CustomerContextHolder 設(shè)置SqlSessionFactory的類(lèi)型
package com.hoo.framework.mybatis.support; /** * <b>function:</b> 多數(shù)據(jù)源 * @author hoojo * @createDate 2013-9-27 上午11:36:57 * @file CustomerContextHolder.java * @package com.hoo.framework.spring.support * @project SHMB * @blog http://blog.csdn.net/IBM_hoojo * @email hoojo_@126.com * @version 1.0 */ public abstract class CustomerContextHolder { public final static String SESSION_FACTORY_MYSQL = "mysql"; public final static String SESSION_FACTORY_ORACLE = "oracle"; private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>(); public static void setContextType(String contextType) { contextHolder.set(contextType); } public static String getContextType() { return contextHolder.get(); } public static void clearContextType() { contextHolder.remove(); } }
2、配置相關(guān)的文件applicationContext-session-factory.xml
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:aop="http://www.springframework.org/schema/aop" 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-3.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd "> <!-- 配置c3p0數(shù)據(jù)源 --> <bean id="dataSourceOracle" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close"> <property name="driverClass" value="${datasource.driver}"/> <property name="jdbcUrl" value="${datasource.url}"/> <property name="user" value="${datasource.username}"/> <property name="password" value="${datasource.password}"/> <property name="acquireIncrement" value="${c3p0.acquireIncrement}"/> <property name="initialPoolSize" value="${c3p0.initialPoolSize}"/> <property name="minPoolSize" value="${c3p0.minPoolSize}"/> <property name="maxPoolSize" value="${c3p0.maxPoolSize}"/> <property name="maxIdleTime" value="${c3p0.maxIdleTime}"/> <property name="idleConnectionTestPeriod" value="${c3p0.idleConnectionTestPeriod}"/> <property name="maxStatements" value="${c3p0.maxStatements}"/> <property name="numHelperThreads" value="${c3p0.numHelperThreads}"/> <property name="preferredTestQuery" value="${c3p0.preferredTestQuery}"/> <property name="testConnectionOnCheckout" value="${c3p0.testConnectionOnCheckout}"/> </bean> <bean id="dataSourceMySQL" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close"> <property name="driverClass" value="com.mysql.jdbc.Driver"/> <property name="jdbcUrl" value="jdbc:mysql://172.31.108.178:3306/world?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull"/> <property name="user" value="root"/> <property name="password" value="jp2011"/> <property name="acquireIncrement" value="${c3p0.acquireIncrement}"/> <property name="initialPoolSize" value="${c3p0.initialPoolSize}"/> <property name="minPoolSize" value="${c3p0.minPoolSize}"/> <property name="maxPoolSize" value="${c3p0.maxPoolSize}"/> <property name="maxIdleTime" value="${c3p0.maxIdleTime}"/> <property name="idleConnectionTestPeriod" value="${c3p0.idleConnectionTestPeriod}"/> <property name="maxStatements" value="${c3p0.maxStatements}"/> <property name="numHelperThreads" value="${c3p0.numHelperThreads}"/> <property name="preferredTestQuery" value="${c3p0.preferredTestQuery}"/> <property name="testConnectionOnCheckout" value="${c3p0.testConnectionOnCheckout}"/> </bean> <!-- 配置SqlSessionFactoryBean --> <bean id="oracleSqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSourceOracle"/> <property name="configLocation" value="classpath:mybatis.xml"/> <!-- mapper和resultmap配置路徑 --> <property name="mapperLocations"> <list> <!-- 表示在com.hoo目錄下的任意包下的resultmap包目錄中,以-resultmap.xml或-mapper.xml結(jié)尾所有文件 --> <value>classpath:com/hoo/framework/mybatis/mybatis-common.xml</value> <value>classpath:com/hoo/**/resultmap/*-resultmap.xml</value> <value>classpath:com/hoo/**/mapper/*-mapper.xml</value> <value>classpath:com/hoo/**/mapper/**/*-mapper.xml</value> </list> </property> </bean> <!-- 配置SqlSessionFactoryBean --> <bean id="mysqlSqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSourceMySQL"/> <property name="configLocation" value="classpath:mybatis.xml"/> <!-- mapper和resultmap配置路徑 --> <property name="mapperLocations"> <list> <!-- 表示在com.hoo目錄下的任意包下的resultmap包目錄中,以-resultmap.xml或-mapper.xml結(jié)尾所有文件 (oracle和mysql掃描的配置和路徑不一樣,如果是公共的都掃描 這里要區(qū)分下,不然就報(bào)錯(cuò) 找不到對(duì)應(yīng)的表、視圖)--> <value>classpath:com/hoo/framework/mybatis/mybatis-common.xml</value> <value>classpath:com/hoo/**/resultmap/*-mysql-resultmap.xml</value> <value>classpath:com/hoo/**/mapper/*-mysql-mapper.xml</value> <value>classpath:com/hoo/**/mapper/**/*-mysql-mapper.xml</value> <value>classpath:com/hoo/**/mapper/**/multiple-datasource-mapper.xml</value> </list> </property> </bean> <!-- 配置自定義的SqlSessionTemplate模板,注入相關(guān)配置 --> <bean id="sqlSessionTemplate" class="com.hoo.framework.mybatis.support.CustomSqlSessionTemplate"> <constructor-arg ref="oracleSqlSessionFactory" /> <property name="targetSqlSessionFactorys"> <map> <entry value-ref="oracleSqlSessionFactory" key="oracle"/> <entry value-ref="mysqlSqlSessionFactory" key="mysql"/> </map> </property> </bean> <!-- 通過(guò)掃描的模式,掃描目錄在com/hoo/任意目錄下的mapper目錄下,所有的mapper都需要繼承SqlMapper接口的接口 --> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="basePackage" value="com.hoo.**.mapper"/> <!-- 注意注入sqlSessionTemplate --> <property name="sqlSessionTemplateBeanName" value="sqlSessionTemplate"/> <property name="markerInterface" value="com.hoo.framework.mybatis.SqlMapper"/> </bean> </beans>
上面的配置關(guān)鍵是在MapperScannerConfigurer中注入sqlSessionTemplate,這個(gè)要注意。當(dāng)我們配置了多個(gè)SqlSessionFactoryBean的時(shí)候,就需要為MapperScannerConfigurer指定一個(gè)sqlSessionFactoryBeanName或是sqlSessionTemplateBeanName。一般情況下注入了sqlSessionTemplateBeanName對(duì)象,那sqlSessionFactory也就有值了。如果單獨(dú)的注入了sqlSessionFactory那么程序會(huì)創(chuàng)建一個(gè)sqlSessionTemplate對(duì)象。我們可以看看代碼SqlSessionFactoryDaoSupport對(duì)象的代碼。如果你不喜歡使用掃描的方式,也可以注入sqlSessionTemplate或繼承sqlSessionTemplate完成數(shù)據(jù)庫(kù)操作。
public abstract class SqlSessionDaoSupport extends DaoSupport { private SqlSession sqlSession; private boolean externalSqlSession; public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) { if (!this.externalSqlSession) { this.sqlSession = new SqlSessionTemplate(sqlSessionFactory); } } public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate) { this.sqlSession = sqlSessionTemplate; this.externalSqlSession = true; } ......
這段代碼很明顯,如果注入了sqlSessionTemplate上面的注入也就不會(huì)執(zhí)行了。如果沒(méi)有注入sqlSessionTemplate,那么會(huì)自動(dòng)new一個(gè)sqlSessionTemplate對(duì)象。
3、編寫(xiě)相關(guān)測(cè)試接口和實(shí)現(xiàn)的mapper.xml
package com.hoo.server.datasource.mapper; import java.util.List; import java.util.Map; import com.hoo.framework.mybatis.SqlMapper; /** * <b>function:</b> MyBatis 多數(shù)據(jù)源 測(cè)試查詢(xún)接口 * @author hoojo * @createDate 2013-10-10 下午04:18:08 * @file MultipleDataSourceMapper.java * @package com.hoo.server.datasource.mapper * @project SHMB * @blog http://blog.csdn.net/IBM_hoojo * @email hoojo_@126.com * @version 1.0 */ public interface MultipleDataSourceMapper extends SqlMapper { public List<Map<String, Object>> execute4MySQL() throws Exception; public List<Map<String, Object>> execute4Oracle() throws Exception; } multiple-datasource-mapper.xml <?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"> <mapper namespace="com.hoo.server.datasource.mapper.MultipleDataSourceMapper"> <select id="execute4Oracle" resultType="map"> <![CDATA[ SELECT * FROM deviceInfo_tab t where rownum < 10 ]]> </select> <select id="execute4MySQL" resultType="map"> <![CDATA[ SELECT * FROM city limit 2 ]]> </select> </mapper>
上面分別查詢(xún)oracle和mysql兩個(gè)數(shù)據(jù)庫(kù)中的table
4、測(cè)試代碼
@Autowired @Qualifier("multipleDataSourceMapper") private MultipleDataSourceMapper mapper; @Test public void testMapper() { CustomerContextHolder.setContextType(CustomerContextHolder.SESSION_FACTORY_MYSQL); try { trace(mapper.execute4MySQL()); } catch (Exception e1) { e1.printStackTrace(); } CustomerContextHolder.setContextType(CustomerContextHolder.SESSION_FACTORY_ORACLE); try { trace(mapper.execute4Oracle()); } catch (Exception e) { e.printStackTrace(); } }
運(yùn)行后發(fā)現(xiàn)能夠順利查詢(xún)出數(shù)據(jù)。
如果你是重寫(xiě)SqlSessionDaoSupport,那么方法如下
package com.hoo.framework.mybatis.support; import java.util.Map; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.mybatis.spring.SqlSessionUtils; import org.mybatis.spring.support.SqlSessionDaoSupport; import org.springframework.beans.BeansException; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; /** * <b>function:</b> MyBatis 動(dòng)態(tài)SqlSessionFactory * @author hoojo * @createDate 2013-10-14 下午02:32:19 * @file DynamicSqlSessionDaoSupport.java * @package com.hoo.framework.mybatis.support * @project SHMB * @blog http://blog.csdn.net/IBM_hoojo * @email hoojo_@126.com * @version 1.0 */ public class DynamicSqlSessionDaoSupport extends SqlSessionDaoSupport implements ApplicationContextAware { private ApplicationContext applicationContext; private Map<Object, SqlSessionFactory> targetSqlSessionFactorys; private SqlSessionFactory defaultTargetSqlSessionFactory; private SqlSession sqlSession; @Override public final SqlSession getSqlSession() { SqlSessionFactory targetSqlSessionFactory = targetSqlSessionFactorys.get(CustomerContextHolder.getContextType()); if (targetSqlSessionFactory != null) { setSqlSessionFactory(targetSqlSessionFactory); } else if (defaultTargetSqlSessionFactory != null) { setSqlSessionFactory(defaultTargetSqlSessionFactory); targetSqlSessionFactory = defaultTargetSqlSessionFactory; } else { targetSqlSessionFactory = (SqlSessionFactory) applicationContext.getBean(CustomerContextHolder.getContextType()); setSqlSessionFactory(targetSqlSessionFactory); } this.sqlSession = SqlSessionUtils.getSqlSession(targetSqlSessionFactory); return this.sqlSession; } @Override protected void checkDaoConfig() { //Assert.notNull(getSqlSession(), "Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required"); } public void setTargetSqlSessionFactorys(Map<Object, SqlSessionFactory> targetSqlSessionFactorys) { this.targetSqlSessionFactorys = targetSqlSessionFactorys; } public void setDefaultTargetSqlSessionFactory(SqlSessionFactory defaultTargetSqlSessionFactory) { this.defaultTargetSqlSessionFactory = defaultTargetSqlSessionFactory; } @Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { this.applicationContext = applicationContext; } }
主要重寫(xiě)getSqlSession方法,上面獲取SqlSessionFactory的方法。
重寫(xiě)好了后就可以配置這個(gè)對(duì)象,配置代碼如下
//每一個(gè)DAO由繼承SqlSessionDaoSupport全部改為DynamicSqlSessionDaoSupport public class UserMapperDaoImpl extends DynamicSqlSessionDaoSupport implements UserDao { public int addUser(User user) { return this.getSqlSession().insert("com.hoo.user.dao.UserDao.addUser", user); } }
在上面的配置文件中加入配置
<bean id="baseDao" class="com.hoo.framework.mybatis.support.DynamicSqlSessionDaoSupport" abstract="true" lazy-init="true"> <property name="targetSqlSessionFactorys"> <map> <entry value-ref="oracleSqlSessionFactory" key="oracle"/> <entry value-ref="mysqlSqlSessionFactory" key="mysql"/> </map> </property> <property name="defaultTargetSqlSessionFactory" ref="oracleSqlSessionFactory"/> </bean> <bean id="userMapperDao" class="com.hoo.user.dao.impl.UserMapperDaoImpl" parent="baseDao"/>
就這樣也可以利用DynamicSqlSessionDaoSupport來(lái)完成動(dòng)態(tài)切換sqlSessionFactory對(duì)象,只需用在注入userMapperDao調(diào)用方法的時(shí)候設(shè)置下CustomerContextHolder的contextType即可。
三、總結(jié)
為了實(shí)現(xiàn)這個(gè)功能看了mybatis-spring-1.2.0.jar這個(gè)包的部分源代碼,代碼內(nèi)容不是很多。所以看了下主要的代碼,下面做些簡(jiǎn)單的介紹。
MapperScannerConfigurer這個(gè)類(lèi)就是我們要掃描的Mapper接口的類(lèi),也就是basePackage中繼承markerInterface配置的接口??梢钥纯碈lassPathBeanDefinitionScanner、ClassPathMapperScanner中的doScan這個(gè)方法。它會(huì)掃描basePackage這個(gè)包下所有接口,在ClassPathScanningCandidateComponentProvider中有這個(gè)方法findCandidateComponents,它會(huì)找到所有的BeanDefinition。
最重要的一點(diǎn)是ClassPathMapperScanner中的doScan這個(gè)方法它會(huì)給這些接口創(chuàng)建一個(gè)MapperFactoryBean。并且會(huì)檢查sqlSessionFactory和sqlSessionTemplate對(duì)象的注入情況。
image 所以我們配置掃描的方式也就相當(dāng)于我們?cè)谂渲梦募薪o每一個(gè)Mapper配置一個(gè)MapperFactoryBean一樣。而這個(gè)MapperFactoryBean又繼承SqlSessionDaoSupport。所以當(dāng)初我想重寫(xiě)MapperScannerConfigurer中的postProcessBeanDefinitionRegistry方法,然后重寫(xiě)方法中的ClassPathMapperScanner中的doScan方法,將definition.setBeanClass(MapperFactoryBean.class);改成自己定義的MapperFactoryBean。最后以失敗告終,因?yàn)檫@里是Spring裝載掃描對(duì)象的時(shí)候都已經(jīng)為這些對(duì)象創(chuàng)建好了代理、設(shè)置好了mapperInterface和注入需要的類(lèi)。所以在調(diào)用相關(guān)操作數(shù)據(jù)庫(kù)的API方法的時(shí)候,設(shè)置對(duì)應(yīng)的SqlSessionFactory也是無(wú)效的。
輾轉(zhuǎn)反側(cè)我看到了SqlSessionTemplate這個(gè)類(lèi),它的功能相當(dāng)于SqlSessionDaoSupport的實(shí)現(xiàn)類(lèi)MapperFactoryBean。最為關(guān)鍵的是SqlSessionTemplate有一個(gè)攔截器SqlSessionInterceptor,它復(fù)制所有SqlSession的創(chuàng)建、提交、關(guān)閉,而且是在每個(gè)方法之前。這點(diǎn)在上面也提到過(guò)了!所以我們只需要在SqlSessionInterceptor方法中獲取SqlSessionFactory的時(shí)候,在這之前調(diào)用下CustomerContextHolder.setContextType方法即可完成數(shù)據(jù)庫(kù)的SqlSessionFactory的切換。而在MapperScannerConfigurer提供了注入SqlSessionFactory和sqlSessionTemplate的方法,如果注入了SqlSessionFactory系統(tǒng)將會(huì)new一個(gè)sqlSessionTemplate,而注入了sqlSessionTemplate就不會(huì)創(chuàng)建其他對(duì)象(見(jiàn)下面代碼)。所以我們配置一個(gè)sqlSessionTemplate并注入到MapperScannerConfigurer中,程序?qū)?huì)使用這個(gè)sqlSessionTemplate。本文最后的實(shí)現(xiàn)方式就是這樣完成的。
public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) { if (!this.externalSqlSession) { this.sqlSession = new SqlSessionTemplate(sqlSessionFactory); } } public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate) { this.sqlSession = sqlSessionTemplate; this.externalSqlSession = true; }
以上所述是小編給大家介紹的Spring3 整合MyBatis3 配置多數(shù)據(jù)源動(dòng)態(tài)選擇SqlSessionFactory詳細(xì)教程,希望對(duì)大家有所幫助,如果大家有任何疑問(wèn)請(qǐng)給我留言,小編會(huì)及時(shí)回復(fù)大家的。在此也非常感謝大家對(duì)億速云網(wǎng)站的支持!
免責(zé)聲明:本站發(fā)布的內(nèi)容(圖片、視頻和文字)以原創(chuàng)、轉(zhuǎn)載和分享為主,文章觀(guān)點(diǎn)不代表本網(wǎng)站立場(chǎng),如果涉及侵權(quán)請(qǐng)聯(lián)系站長(zhǎng)郵箱:is@yisu.com進(jìn)行舉報(bào),并提供相關(guān)證據(jù),一經(jīng)查實(shí),將立刻刪除涉嫌侵權(quán)內(nèi)容。