Spring Roo兩個數(shù)據(jù)庫的配置

September , 2011 | Posted by admin | No Comments

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經(jīng)常可以在Spring Roo論壇上看到一個經(jīng)常的問題。問題是“如何配置使得應(yīng)用可以處理兩個數(shù)據(jù)庫”。

這對Spring Roo來說，是足夠麻煩的問題，這個問題涉及了JPA和Spring持久化棧。所以，我相信這對所有的Spring開發(fā)社區(qū)都要處理這個問題。

假設(shè)讀者是Java開發(fā)人員，對Spring Roo有些熟悉。我關(guān)注如何獲取配置。查看幫助，請訪問http://www./roo。

解決問題

創(chuàng)建了以下最小的Roo項目。修改配置，每個實體都來自于不同的獨立的數(shù)據(jù)庫。

project --topLevelPackage org.pragmatikroo.twodb
persistence setup --provider HIBERNATE --database MYSQL --userName <username> --password <password> --databaseName twodbone
logging setup --level DEBUG --package PERSISTENCE
entity --class ~.domain.DbOne
field string --fieldName name
entity --class ~.domain.DbTwo
field string --fieldName name
perform clean
perform eclipse
exit

原始Database.properties文件

database.password=<password>
database.url=jdbc\:mysql\://localhost\:3306/twodb
database.username=<username>
database.driverClassName=com.mysql.jdbc.Driver

修改后的Database.properties文件

database.password1=<password1>
database.url1=jdbc\:mysql\://localhost\:3306/twodbone
database.username1=<username1>
database.password2=<password1>
database.url2=jdbc\:mysql\://localhost\:3306/twodbtwo
database.username2=<username2>
database.driverClassName=com.mysql.jdbc.Driver

基本上，我已經(jīng)從原始文件復(fù)制了一個拷貝定義第二個數(shù)據(jù)庫。對其他文件的模式也是重復(fù)的。

修改后的Persistence.xml文件

<persistence-unit name="persistenceUnit1" transaction-type="RESOURCE_LOCAL">
      <provider>org.hibernate.ejb.HibernatePersistence</provider>
      <class>org.josean.twodb.domain.DbOne</class>
      <exclude-unlisted-classes>true</exclude-unlisted-classes>
      <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect"/>
            <!-- value="create" to build a new database on each run; value="update" to modify an existing database; value="create-drop" means the same as "create" but also drops tables when Hibernate closes; value="validate" makes no changes to the database -->
            <property name="hibernate.hbm2ddl.auto" value="update"/>
            <property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.ImprovedNamingStrategy"/>
            <property name="hibernate.connection.charSet" value="UTF-8"/>
            <!-- Uncomment the following two properties for JBoss only -->
            <!-- property name="hibernate.validator.apply_to_ddl" value="false" /-->
            <!-- property name="hibernate.validator.autoregister_listeners" value="false" /-->
            </properties>
</persistence-unit>
<persistence-unit name="persistenceUnit2" transaction-type="RESOURCE_LOCAL">
      <provider>org.hibernate.ejb.HibernatePersistence</provider>
      <class>org.josean.twodb.domain.DbTwo</class>
      <exclude-unlisted-classes>true</exclude-unlisted-classes>
      <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect"/>
            <!-- value="create" to build a new database on each run; value="update" to modify an existing database; value="create-drop" means the same as "create" but also drops tables when Hibernate closes; value="validate" makes no changes to the database -->
            <property name="hibernate.hbm2ddl.auto" value="update"/>
            <property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.ImprovedNamingStrategy"/>
            <property name="hibernate.connection.charSet" value="UTF-8"/>
            <!-- Uncomment the following two properties for JBoss only -->
            <!-- property name="hibernate.validator.apply_to_ddl" value="false" /-->
            <!-- property name="hibernate.validator.autoregister_listeners" value="false" /-->
            </properties>
</persistence-unit>

為第二個數(shù)據(jù)庫復(fù)制持久化單元代碼，定義了唯一的id。重要的是：添加和。持久化單元處理的每個實體都必須包含在內(nèi)。

修改后的ApplicationContext.xml文件

<bean class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" id="dataSource1">
      <property name="driverClassName" value="${database.driverClassName}"/>
      <property name="url" value="${database.url1}"/>
      <property name="username" value="${database.username1}"/>
      <property name="password" value="${database.password1}"/>
      <property name="validationQuery" value="SELECT 1 FROM DUAL"/>
      <property name="testOnBorrow" value="true"/>
</bean>
<bean class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean" id="entityManagerFactory1">
      <property name="dataSource" ref="dataSource1"/>
      <property name="persistenceUnitName" value="persistenceUnit1"/>
</bean>
<tx:annotation-driven mode="aspectj" transaction-manager="transactionManager1" />
<bean class="org.springframework.orm.jpa.JpaTransactionManager" id="transactionManager1">
      <property name="entityManagerFactory" ref="entityManagerFactory1" />
</bean>
<bean class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" id="dataSource2">
      <property name="driverClassName" value="${database.driverClassName}"/>
      <property name="url" value="${database.url2}"/>
      <property name="username" value="${database.username2}"/>
      <property name="password" value="${database.password2}"/>
      <property name="validationQuery" value="SELECT 1 FROM DUAL"/>
      <property name="testOnBorrow" value="true"/>
</bean>
<bean class="org.springframework.orm.jpa.JpaTransactionManager" id="transactionManager2">
      <property name="entityManagerFactory" ref="entityManagerFactory2"/>
</bean>
<tx:annotation-driven mode="aspectj" transaction-manager="transactionManager2" />
<bean class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean" id="entityManagerFactory2">
      <property name="dataSource" ref="dataSource2"/>
      <property name="persistenceUnitName" value="persistenceUnit2"/>
</bean>

其他文件的處理過程類似。添加屬性到entityManagerFactory beans中。

修改后的Web.xml文件

<filter>
      <filter-name>Spring OpenEntityManagerInViewFilter1</filter-name>
      <filter-class>org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter</filter-class>
      <init-param>
            <param-name>entityManagerFactoryBeanName</param-name>
            <param-value>entityManagerFactory1</param-value>
      </init-param>
</filter>
<filter>
      <filter-name>Spring OpenEntityManagerInViewFilter2</filter-name>
      <filter-class>org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter</filter-class>
      <init-param>
            <param-name>entityManagerFactoryBeanName</param-name>
            <param-value>entityManagerFactory2</param-value>
      </init-param>
</filter>

就是這樣！應(yīng)用可以部署和測試了。

總結(jié)

已經(jīng)演示了如何安裝Spring web應(yīng)用的上下文，使得應(yīng)用可以訪問第二個數(shù)據(jù)庫，尤其對Spring Roo開發(fā)人員有用。