分布式数据库配置(转载)

在SpringSide3社区中,不断有人提出多数据源配置的问题,但是时至今日却一直没有一个完美的答案。经过一个星期的折腾,我总算搞清楚了在SpringSide3中配置多数据源的各种困难并加以解决,在这里,特地把我配置SpringSide3项目中多数据源的过程写出来,与大家分享。

我使用的SpringSide的版本是江南白衣最新发布的3.1.4版,在上一篇博文中,记录了我折腾的全过程,感兴趣的朋友可以看看:

http://www.blogjava.net/youxia/archive/2009/07/12/286454.html

下面进入正题:

结论:在基于SpringSide3的项目中,如果要使用多个数据库,首先要配置多个数据源,然后配置多个SessionFactory,这本身没有问题,但是一涉及到事务,问题就来了,在多数据源的环境下,必须使用JTATransactionManager,而使用JTATransactionManager,就必须得有提供JTA功能的应用服务器或提供JTA功能的别的什么组件。

以上结论绝对正确,是属于SpringSide3中关于使用多个数据库的最权威解答,下面来看具体过程:

方法一、使用GlassFish应用服务器

1、准备GlassFish服务器,下载地址为http://download.java.net/glassfish/v3/promoted/,我选择的是08-Jul-200917:20发布的大小为72M的latest-glassfish.zip,这里需要强调的一点是千万不要选择latest-glassfish-windows.exe这个版本,因为这个版本在Windows环境中只安装GlassFish而不提供合理的初始化配置,对于新手来说使用门槛太高,而ZIP版一解压缩就可以使用,其服务器是配置好了的;

2、在GlassFish中配置多个数据源,启动GlassFish后,访问4848端口就可以进入到GlassFish的管理界面,在其中配置两个数据源,其资源名称分别为jdbc/dataSourceContent和jdbc/dataSourceIndex,如下图:

3、在项目中配置多个DataSource和多个SessionFactory,并选择JTATransactionManager作为事务管理器,这里的DataSource是使用JNDI查找从应用服务器中获得的。下面是我项目中的applicationContext.xml文件:

<?xmlversion="1.0"encoding="UTF-8"?>

<beansxmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:jee="http://www.springframework.org/schema/jee"xmlns:tx="http://www.springframework.org/schema/tx"

xmlns:context="http://www.springframework.org/schema/context"

xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-2.5.xsdhttp://www.springframework.org/schema/txhttp://www.springframework.org/schema/tx/spring-tx-2.5.xsdhttp://www.springframework.org/schema/jeehttp://www.springframework.org/schema/jee/spring-jee-2.5.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context-2.5.xsd"

default-lazy-init="true">

<description>Spring公共配置文件</description>

<!--定义受环境影响易变的变量-->

<beanclass="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">

<propertyname="systemPropertiesModeName"value="SYSTEM_PROPERTIES_MODE_OVERRIDE"/>

<propertyname="ignoreResourceNotFound"value="true"/>

<propertyname="locations">

<list>

<!--标准配置-->

<value>classpath*:/application.properties</value>

</list>

</property>

</bean>

<!--使用annotation自动注册bean,并保证@Required,@Autowired的属性被注入-->

<context:component-scanbase-package="cn.puretext"/>

<!--数据源配置,使用应用服务器的数据库连接池-->

<jee:jndi-lookupid="dataSourceContent"jndi-name="jdbc/dataSourceContent"/>

<jee:jndi-lookupid="dataSourceIndex"jndi-name="jdbc/dataSourceIndex"/>

<!--Hibernate配置-->

<beanid="sessionFactoryContent"class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">

<propertyname="dataSource"ref="dataSourceContent"/>

<propertyname="namingStrategy">

<beanclass="org.hibernate.cfg.ImprovedNamingStrategy"/>

</property>

<propertyname="hibernateProperties">

<props>

<propkey="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</prop>

<propkey="hibernate.show_sql">${hibernate.show_sql}</prop>

<propkey="hibernate.format_sql">${hibernate.format_sql}</prop>

<propkey="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider

</prop>

<propkey="hibernate.cache.provider_configuration_file_resource_path">${hibernate.ehcache_config_file}</prop>

</props>

</property>

<propertyname="packagesToScan"value="cn.puretext.entity.*"/>

</bean>

<beanid="sessionFactoryIndex"class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">

<propertyname="dataSource"ref="dataSourceIndex"/>

<propertyname="namingStrategy">

<beanclass="org.hibernate.cfg.ImprovedNamingStrategy"/>

</property>

<propertyname="hibernateProperties">

<props>

<propkey="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</prop>

<propkey="hibernate.show_sql">${hibernate.show_sql}</prop>

<propkey="hibernate.format_sql">${hibernate.format_sql}</prop>

<propkey="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider

</prop>

<propkey="hibernate.cache.provider_configuration_file_resource_path">${hibernate.ehcache_config_file}</prop>

</props>

</property>

<propertyname="packagesToScan"value="cn.puretext.entity.*"/>

</bean>

<!--事务管理器配置,多数据源JTA事务-->

<beanid="transactionManager"class="org.springframework.transaction.jta.JtaTransactionManager"/>

<!--使用annotation定义事务-->

<tx:annotation-driventransaction-manager="transactionManager"/>

</beans>

4、由于配置了多个SessionFactory,所以需要在web.xml中配置两个OpenSessionInViewFilter,下面是我的web.xml文件:

<?xmlversion="1.0"encoding="UTF-8"?>

<web-appversion="2.4"xmlns="http://java.sun.com/xml/ns/j2ee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/j2eehttp://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<display-name>PureText</display-name>

<!--SpringApplicationContext配置文件的路径,可使用通配符,多个路径用,号分隔

此参数用于后面的SpringContextLoader-->

<context-param>

<param-name>contextConfigLocation</param-name>

<param-value>classpath*:/applicationContext*.xml</param-value>

</context-param>

<!--CharacterEncodingfilter-->

<filter>

<filter-name>encodingFilter</filter-name>

<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>

<init-param>

<param-name>encoding</param-name>

<param-value>UTF-8</param-value>

</init-param>

<init-param>

<param-name>forceEncoding</param-name>

<param-value>true</param-value>

</init-param>

</filter>

<filter>

<filter-name>hibernateOpenSessionInViewFilterContent</filter-name>

<filter-class>org.springside.modules.orm.hibernate.OpenSessionInViewFilter</filter-class>

<init-param>

<param-name>excludeSuffixs</param-name>

<param-value>js,css,jpg,gif</param-value>

</init-param>

<init-param>

<param-name>sessionFactoryBeanName</param-name>

<param-value>sessionFactoryContent</param-value>

</init-param>

</filter>

<filter>

<filter-name>hibernateOpenSessionInViewFilterIndex</filter-name>

<filter-class>org.springside.modules.orm.hibernate.OpenSessionInViewFilter</filter-class>

<init-param>

<param-name>excludeSuffixs</param-name>

<param-value>js,css,jpg,gif</param-value>

</init-param>

<init-param>

<param-name>sessionFactoryBeanName</param-name>

<param-value>sessionFactoryIndex</param-value>

</init-param>

</filter>

<!--SpringSecurityfilter-->

<filter>

<filter-name>springSecurityFilterChain</filter-name>

<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>

</filter>

<!--Struts2filter-->

<filter>

<filter-name>struts2Filter</filter-name>

<filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>

</filter>

<filter-mapping>

<filter-name>encodingFilter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<filter-mapping>

<filter-name>springSecurityFilterChain</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<filter-mapping>

<filter-name>hibernateOpenSessionInViewFilterContent</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<filter-mapping>

<filter-name>hibernateOpenSessionInViewFilterIndex</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<filter-mapping>

<filter-name>struts2Filter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<!--Spring的ApplicationContext载入-->

<listener>

<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>

</listener>

<!--Spring刷新Introspector防止内存泄露-->

<listener>

<listener-class>org.springframework.web.util.IntrospectorCleanupListener</listener-class>

</listener>

<!--session超时定义,单位为分钟-->

<session-config>

<session-timeout>20</session-timeout>

</session-config>

<!--出错页面定义-->

<error-page>

<exception-type>java.lang.Throwable</exception-type>

<location>/common/500.jsp</location>

</error-page>

<error-page>

<error-code>500</error-code>

<location>/common/500.jsp</location>

</error-page>

<error-page>

<error-code>404</error-code>

<location>/common/404.jsp</location>

</error-page>

<error-page>

<error-code>403</error-code>

<location>/common/403.jsp</location>

</error-page>

</web-app>

5、由于项目中有多个SessionFactory,所以编写Dao层的时候需要使用@Resource注解来明确指定使用哪一个SessionFactory,如下面代码所示,ArticleDao使用sessionFactoryContent,而ArticleIndexDao使用sessionFactoryIndex:

packagecn.puretext.dao;

importjavax.annotation.Resource;

importorg.hibernate.SessionFactory;

importorg.springframework.stereotype.Repository;

importorg.springside.modules.orm.hibernate.HibernateDao;

importcn.puretext.entity.web.Article;

@Repository

publicclassArticleDaoextendsHibernateDao<Article,Long>{

@Override

@Resource(name="sessionFactoryContent")

publicvoidsetSessionFactory(SessionFactorysessionFactory){

//TODOAuto-generatedmethodstub

super.setSessionFactory(sessionFactory);

}

}

packagecn.puretext.dao;

importjavax.annotation.Resource;

importorg.hibernate.SessionFactory;

importorg.springframework.stereotype.Repository;

importorg.springside.modules.orm.hibernate.HibernateDao;

importcn.puretext.entity.web.ArticleIndex;

@Repository

publicclassArticleIndexDaoextendsHibernateDao<ArticleIndex,Long>{

@Override

@Resource(name="sessionFactoryIndex")

publicvoidsetSessionFactory(SessionFactorysessionFactory){

//TODOAuto-generatedmethodstub

super.setSessionFactory(sessionFactory);

}

}

6、在GlassFish中部署项目,部署项目的时候依然使用前面提到的GlassFish的管理界面,这里不赘述。

经过以上六步,就可以成功的在基于SpringSide3的项目中使用多个数据库。如果你确实很不相使用GlassFish,而对Tomcat情有独钟的话,就要使用我前面提到的“提供JTA功能的其它组件”了。在这里,我推荐使用Atomikos,这是一个很优秀的JTA实现,它的官方网站为www.atomikos.com,它提供开源版和商业版,下面是从其官方网站上截取的图片:

很烦人的是,该网站不直接提供下载地址,如果要下载,就必须先填写姓名邮箱和电话,如果大家不想填写这些信息,可以直接进入这个网址下载http://www.atomikos.com/Main/InstallingTransactionsEssentials,我选择的是3.5.5版。

方法二、使用Tomcat服务器和Atomikos

1、将Atomikos整合到Tomcat服务器中,其步骤可以参考Atomikos的文档,如下:

http://www.atomikos.com/Documentation/Tomcat6Integration33

2、在Tomcat中配置JNDI数据源,方法是修改Tomcat的content.xml文件,在文件中加入如下两个<Resource/>和一个<Transaction/>:

<Transactionfactory="com.atomikos.icatch.jta.UserTransactionFactory"/>

<Resourcename="jdbc/dataSourceContent"auth="Container"

type="com.atomikos.jdbc.AtomikosDataSourceBean"factory="com.atomikos.tomcat.BeanFactory"

uniqueResourcename="jdbc/myDB"xaDataSourceClassname="com.mysql.jdbc.jdbc2.optional.MysqlXADataSource"

xaProperties.databasename="puretext"xaProperties.servername="localhost"

xaProperties.port="3306"xaProperties.user="USER"

xaProperties.password="PASSWORD"xaProperties.url="jdbc:mysql://localhost:3306/puretext"/>

<Resourcename="jdbc/dataSourceIndex"auth="Container"

type="com.atomikos.jdbc.AtomikosDataSourceBean"factory="com.atomikos.tomcat.BeanFactory"

uniqueResourcename="jdbc/myDB"xaDataSourceClassname="com.mysql.jdbc.jdbc2.optional.MysqlXADataSource"

xaProperties.databasename="puretext_index"xaProperties.servername="localhost"

xaProperties.port="3306"xaProperties.user="USER"

xaProperties.password="PASSWORD"xaProperties.url="jdbc:mysql://localhost:3306/puretext_index"/>

剩下的四步就和使用GlassFish的第3、4、5、6步一模一样了,这里不赘述。

以上Atomikos和Tomcat的整合方案有时候或多或少出现一点问题,这些问题基本上都和JNDI有关,我想可能是Tomcat实现的JNDI配置有问题。如果出现这样的问题无法解决的话,还有第三种方案,那就是直接在Spring的配置文件中配置Atomikos的JTA相关组件。

方法三、直接在Spring的配置文件中配置Atomikos的JTA相关组件

1、将下载的Atomikos中的jta.properties拷贝到项目的classpath中,将Atomikos的相关jar文件拷贝到项目的classpath中。

2、在项目的applicationContext.xml文件中配置JTA的相关组件,配置文件如下:

<?xmlversion="1.0"encoding="UTF-8"?>

<beansxmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:jee="http://www.springframework.org/schema/jee"xmlns:tx="http://www.springframework.org/schema/tx"

xmlns:context="http://www.springframework.org/schema/context"

xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-2.5.xsdhttp://www.springframework.org/schema/txhttp://www.springframework.org/schema/tx/spring-tx-2.5.xsdhttp://www.springframework.org/schema/jeehttp://www.springframework.org/schema/jee/spring-jee-2.5.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context-2.5.xsd"

default-lazy-init="true">

<description>Spring公共配置文件</description>

<!--定义受环境影响易变的变量-->

<beanclass="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">

<propertyname="systemPropertiesModeName"value="SYSTEM_PROPERTIES_MODE_OVERRIDE"/>

<propertyname="ignoreResourceNotFound"value="true"/>

<propertyname="locations">

<list>

<!--标准配置-->

<value>classpath*:/application.properties</value>

</list>

</property>

</bean>

<!--使用annotation自动注册bean,并保证@Required,@Autowired的属性被注入-->

<context:component-scanbase-package="cn.puretext"/>

<beanid="dataSourceContent"class="com.atomikos.jdbc.AtomikosDataSourceBean"init-method="init"destroy-method="close">

<propertyname="uniqueResourceName">

<value>jdbc/dataSourceContent</value>

</property>

<propertyname="xaDataSourceClassName">

<value>com.mysql.jdbc.jdbc2.optional.MysqlXADataSource</value>

</property>

<propertyname="xaProperties">

<props>

<propkey="serverName">localhost</prop>

<propkey="portNumber">3306</prop>

<propkey="databaseName">puretext</prop>

<propkey="user">***</prop>

<propkey="password">***</prop>

</props>

</property>

<propertyname="poolSize">

<value>3</value>

</property>

</bean>

<beanid="dataSourceIndex"class="com.atomikos.jdbc.AtomikosDataSourceBean"init-method="init"destroy-method="close">

<propertyname="uniqueResourceName">

<value>jdbc/dataSourceIndex</value>

</property>

<propertyname="xaDataSourceClassName">

<value>com.mysql.jdbc.jdbc2.optional.MysqlXADataSource</value>

</property>

<propertyname="xaProperties">

<props>

<propkey="serverName">localhost</prop>

<propkey="portNumber">3306</prop>

<propkey="databaseName">puretext_index</prop>

<propkey="user">***</prop>

<propkey="password">***</prop>

</props>

</property>

<propertyname="poolSize">

<value>3</value>

</property>

</bean>

<!--Hibernate配置-->

<beanid="sessionFactoryContent"class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">

<propertyname="dataSource"ref="dataSourceContent"/>

<propertyname="namingStrategy">

<beanclass="org.hibernate.cfg.ImprovedNamingStrategy"/>

</property>

<propertyname="hibernateProperties">

<props>

<propkey="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</prop>

<propkey="hibernate.show_sql">${hibernate.show_sql}</prop>

<propkey="hibernate.format_sql">${hibernate.format_sql}</prop>

<propkey="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider

</prop>

<propkey="hibernate.cache.provider_configuration_file_resource_path">${hibernate.ehcache_config_file}</prop>

</props>

</property>

<propertyname="packagesToScan"value="cn.puretext.entity.*"/>

</bean>

<beanid="sessionFactoryIndex"class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">

<propertyname="dataSource"ref="dataSourceIndex"/>

<propertyname="namingStrategy">

<beanclass="org.hibernate.cfg.ImprovedNamingStrategy"/>

</property>

<propertyname="hibernateProperties">

<props>

<propkey="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</prop>

<propkey="hibernate.show_sql">${hibernate.show_sql}</prop>

<propkey="hibernate.format_sql">${hibernate.format_sql}</prop>

<propkey="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider

</prop>

<propkey="hibernate.cache.provider_configuration_file_resource_path">${hibernate.ehcache_config_file}</prop>

</props>

</property>

<propertyname="packagesToScan"value="cn.puretext.entity.*"/>

</bean>

<!--事务管理器配置,多数据源JTA事务-->

<beanid="atomikosTransactionManager"class="com.atomikos.icatch.jta.UserTransactionManager"init-method="init"destroy-method="close">

<propertyname="forceShutdown"><value>true</value></property>

</bean>

<beanid="atomikosUserTransaction"class="com.atomikos.icatch.jta.UserTransactionImp">

<propertyname="transactionTimeout"value="300"/>

</bean>

<beanid="transactionManager"class="org.springframework.transaction.jta.JtaTransactionManager">

<propertyname="transactionManager"ref="atomikosTransactionManager"/>

<propertyname="userTransaction"ref="atomikosUserTransaction"/>

</bean>

<!--使用annotation定义事务-->

<tx:annotation-driventransaction-manager="transactionManager"/>

</beans>

3、在web.xml中配置多个OpenSessionInViewFilter,其配置方法同前。

4、在Dao类中使用@Resource指定使用哪一个sessionFactory。

5、运行项目,成功。

在以上的三个方法中,我强烈推荐第三种,因为该方法只需要将Atomikos的相关文件拷贝到项目的classpath中,并在applicationContext.xml文件中完成配置即可,不需要修改应用服务器的任何文件,是非侵入性的,是最轻量级的,同时,也是配置起来最容易成功的,在我的测试过程中基本上是一次成功,没有报错。

好了,就写到这里了,希望SpringSide的fans们少走弯路,天天开心。

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