Spring3 整合MyBatis3 配置多数据源 动态选择SqlSessionFactory.docx

一、摘要上两篇文章分别介绍了Spring3.3 整合 Hibernate3、MyBatis3.2 配置多数据源/动态切换数据源 方法和Spring3 整合Hibernate3.5 动态切换SessionFactory （切换数据库方言），这篇文章将介绍Spring整合Mybatis 如何完成SqlSessionFactory的动态切换的。并且会简单的介绍下MyBatis整合Spring中的官方的相关代码。Spring整合MyBatis切换SqlSessionFactory有两种方法，第一、 继承SqlSessionDaoSupport，重写获取SqlSessionFactory的方法。第二、继承SqlSessionTemplate 重写getSqlSessionFactory、getConfiguration和SqlSessionInterceptor这个拦截器。其中最为关键还是继承SqlSessionTemplate 并重写里面的方法。而Spring整合MyBatis也有两种方式，一种是配置MapperFactoryBean，另一种则是利用MapperScannerConfigurer进行扫描接口或包完成对象的自动创建。相对来说后者更方便些。MapperFactoryBean继承了SqlSessionDaoSupport也就是动态切换SqlSessionFactory的第一种方法，我们需要重写和实现SqlSessionDaoSupport方法，或者是继承MapperFactoryBean来重写覆盖相关方法。如果利用MapperScannerConfigurer的配置整合来切换SqlSessionFactory，那么我们就需要继承SqlSessionTemplate，重写上面提到的方法。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。因为SqlSessionTemplate的创建也是需要注入SqlSessionFactory的。二、实现代码1、继承SqlSessionTemplate 重写getSqlSessionFactory、getConfiguration和SqlSessionInterceptorpackage 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;/* * function: 继承SqlSessionTemplate 重写相关方法 * author hoojo * createDate 2013-10-18 下午03:07:46 * file CustomSqlSessionTemplate.java * package com.hoo.framework.mybatis.support * project SHMB * blog /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 targetSqlSessionFactorys; private SqlSessionFactory defaultTargetSqlSessionFactory; public void setTargetSqlSessionFactorys(Map 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 selectOne(String statement) return this.sqlSessionProxy. selectOne(statement); /* * inheritDoc */ public T selectOne(String statement, Object parameter) return this.sqlSessionProxy. selectOne(statement, parameter); /* * inheritDoc */ public Map selectMap(String statement, String mapKey) return this.sqlSessionProxy. selectMap(statement, mapKey); /* * inheritDoc */ public Map selectMap(String statement, Object parameter, String mapKey) return this.sqlSessionProxy. selectMap(statement, parameter, mapKey); /* * inheritDoc */ public Map selectMap(String statement, Object parameter, String mapKey, RowBounds rowBounds) return this.sqlSessionProxy. selectMap(statement, parameter, mapKey, rowBounds); /* * inheritDoc */ public List selectList(String statement) return this.sqlSessionProxy. selectList(statement); /* * inheritDoc */ public List selectList(String statement, Object parameter) return this.sqlSessionProxy. selectList(statement, parameter); /* * inheritDoc */ public List selectList(String statement, Object parameter, RowBounds rowBounds) return this.sqlSessionProxy. 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 getMapper(Class 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 flushStatements() return this.sqlSessionProxy.flushStatements(); /* * Proxy needed to route MyBatis method calls to the proper SqlSession got from Springs 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() sqlSmit(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(); 重写后的getSqlSessionFactory方法会从我们配置的SqlSessionFactory集合targetSqlSessionFactorys或默认的defaultTargetSqlSessionFactory中获取Session对象。而改写的SqlSessionInterceptor 是这个MyBatis整合Spring的关键，所有的SqlSessionFactory对象的session都将在这里完成创建、提交、关闭等操作。所以我们改写这里的代码，在这里获取getSqlSessionFactory的时候，从多个SqlSessionFactory中获取我们设置的那个即可。上面添加了targetSqlSessionFactorys、defaultTargetSqlSessionFactory两个属性来配置多个SqlSessionFactory对象和默认的SqlSessionFactory对象。CustomerContextHolder 设置SqlSessionFactory的类型package com.hoo.framework.mybatis.support;/* * function: 多数据源 * author hoojo * createDate 2013-9-27 上午11:36:57 * file CustomerContextHolder.java * package com.hoo.framework.spring.support * project SHMB * blog /IBM_hoojo * email hoojo_126.com * version 1.0 */public abstract class CustomerContextHolder public final static String SESSION_FACTORY_MYS