@Autowired and @Qualifier

"Your best friends could be @Autowired and @Qualifier"
I have to migrate data from DB2 to Oracle, both databases have the same structure, well, my Oracle has better design, but I'm reusing the some objects, like POJO's and DAO's, the only thing I changed were my mappings, because I have to keep my mappings for DB2 and for Oracle.
If I have the same DAO for both databases, what can I do?
daoApplicationContext.xml <?xml version="1.0" encoding="UTF-8" ?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:jee="http://www.springframework.org/schema/jee" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-2.5.xsd"> <!-- ========================= Data Sources ============================= --> <bean id="db2DS" class="org.apache.tomcat.dbcp.dbcp.BasicDataSource" destroy-method="close"> <property name="driverClassName" value="COM.ibm.db2.jdbc.app.DB2Driver"/> <property name="url" value="jdbc:db2:best"/> <property name="username" value="${userId}"/> <property name="password" value="${pwd}"/> </bean> <bean id="oracleDS" class="org.apache.tomcat.dbcp.dbcp.BasicDataSource" destroy-method="close"> <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver"/> <property name="url" value="jdbc:oracle:thin:@twsifcmtzdt01.tdc.vzwcorp.com:1535:mkssbxdb"/> <property name="username" value="${userId}"/> <property name="password" value="${pwd}"/> </bean> <!--============================= SessionFactory ===============================--> <bean id="sessionFactoryDB2" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"> <property name="dataSource" ref="db2DS" /> <property name="configLocation"> <value>classpath:com/vzw/dvs/mapping/mappingDB2.cfg.xml</value> </property> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect"> org.hibernate.dialect.DB2Dialect </prop> <prop key="hibernate.show_sql">false</prop> <prop key="hibernate.format_sql">true</prop> <prop key="hibernate.order_updates">true</prop> <prop key="hibernate.generate_statistics">true</prop> <prop key="hibernate.use_sql_comments">false</prop> <prop key="hibernate.bytecode.use_reflection_optimizer"> false </prop> <prop key="hibernate.jdbc.batch_size">15</prop> <prop key="hibernate.jdbc.batch_versioned_data"> true </prop> <prop key="hibernate.query.factory_class"> org.hibernate.hql.ast.ASTQueryTranslatorFactory </prop> <prop key="hibernate.connection.isolation">4</prop> </props> </property> </bean> <bean id="sessionFactoryOracle" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"> <property name="dataSource" ref="oracleDS" /> <property name="configLocation"> <value>classpath:com/vzw/dvs/mapping/mappingOracle.cfg.xml</value> </property> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect"> org.hibernate.dialect.Oracle10gDialect </prop> <prop key="hibernate.show_sql">false</prop> <prop key="hibernate.format_sql">true</prop> <prop key="hibernate.order_updates">true</prop> <prop key="hibernate.generate_statistics">true</prop> <prop key="hibernate.use_sql_comments">false</prop> <prop key="hibernate.bytecode.use_reflection_optimizer"> false </prop> <prop key="hibernate.jdbc.batch_size">15</prop> <prop key="hibernate.jdbc.batch_versioned_data"> true </prop> <prop key="hibernate.query.factory_class"> org.hibernate.hql.ast.ASTQueryTranslatorFactory </prop> <prop key="hibernate.connection.isolation">4</prop> </props> </property> </bean> <!-- ============================ DAOs DB2 ================================== --> <bean id="UserDAOdb2" class="com.vzw.dvs.core.persistence.dao.impl.UserDAOImpl"> <property name="sessionFactory" ref="sessionFactoryDB2" /> </bean> <!-- ============================ DAOs Oracle ================================== --> <bean id="UserDAO" class="com.vzw.dvs.core.persistence.dao.impl.UserDAOImpl"> <property name="sessionFactory" ref="sessionFactoryOracle" /> </bean> </beans>
As you can see, I have 2 different DAO's sharing the same Interface & Implementation, but each one belongs to a different "sessionFactory" <bean id="UserDAOdb2" class="com.vzw.dvs.core.persistence.dao.impl.UserDAOImpl"> <property name="sessionFactory" ref="sessionFactoryDB2" /> </bean> <bean id="UserDAO" class="com.vzw.dvs.core.persistence.dao.impl.UserDAOImpl"> <property name="sessionFactory" ref="sessionFactoryOracle" /> </bean> serviceApplicationContext.xml <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:util="http://www.springframework.org/schema/util" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"> <!-- =============== JTA ==========================================--> <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory"> <ref bean="sessionFactoryOracle" /> </property> </bean> <!--====================== Transaction Managers with Annotations =====================--> <tx:annotation-driven transaction-manager="transactionManager" /> <!--====================== Enable Autowire =====================--> <context:annotation-config /> <!--================== Implementation of Services =====================--> <bean id="MigrateTablesService" class="com.vzw.dvs.core.business.service.web.impl.MigrateTablesServiceImpl"/> </beans>
Nothing special, right? But now here it comes the interesting part, because @Autowired by itself it will inject the given bean in your ServiceImpl, but you must have only one bean of that type. In my case I have more than 1, so @Autowired will throw an error when loading the context.
Then it comes @Qualifier which will match based on the given name, and problem solved chavos!!!
public class MigrateTablesServiceImpl implements MigrateTablesService { private static final Logger log = Logger.getLogger(MigrateTablesServiceImpl.class); @Autowired @Qualifier("UserDAOdb2") private UserDAO userDAOdb2; @Autowired @Qualifier("UserDAO") private UserDAO userDAO; @Transactional(readOnly = false, propagation = Propagation.REQUIRED) public boolean doMigrateUser() { log.debug("Migrating User"); boolean result = false; try{ List<User> listItems = this.userDAOdb2.getAll(); for(User transientInstance: listItems){ log.debug("Item retrieved from DB2 "+transientInstance); User user = new User(); BeanUtils.copyProperties(transientInstance, user); //Trim Strings user.setDbUserId(StringUtils.trim(transientInstance.getDbUserId())); user.setBudgetmanagerind(StringUtils.trim(transientInstance.getBudgetmanagerind())); user.setDashboardaccess(StringUtils.trim(transientInstance.getDashboardaccess())); user.setDirectorusercd(StringUtils.trim(transientInstance.getDirectorusercd())); user.setEmail(StringUtils.trim(transientInstance.getEmail())); user.setFirstname(StringUtils.trim(transientInstance.getFirstname())); user.setFunctionalareacd(StringUtils.trim(transientInstance.getFunctionalareacd())); user.setHomephone(StringUtils.trim(transientInstance.getHomephone())); user.setInternalit(StringUtils.trim(transientInstance.getInternalit())); user.setLastname(StringUtils.trim(transientInstance.getLastname())); user.setMobilephone(StringUtils.trim(transientInstance.getMobilephone())); user.setPassword(StringUtils.trim(transientInstance.getPassword())); user.setUserid(StringUtils.trim(transientInstance.getUserid())); user.setUserstatuscd(StringUtils.trim(transientInstance.getUserstatuscd())); user.setVpid(StringUtils.trim(transientInstance.getVpid())); user.setUtilizationtarget(StringUtils.trim(transientInstance.getUtilizationtarget())); user.setWorkphone(StringUtils.trim(transientInstance.getWorkphone())); if(user.getDbTimestamp()==null){ user.setDbTimestamp(new Date()); } this.userDAO.save(user); } result = true; }catch (Exception ex) { log.warn(ex); } log.debug("Done"); return result; }
Notes: I used org.springframework.beans.BeanUtils to create a copy of my bean (pojo) returned from DB2 into a non-persistent Pojo which I'll manipulate before inserting into Oracle (DB2 completes each column value with spaces to achieve the given size of that column, so each time you query a DB2 column you'll get a lot of extra spaces)