具有Spring+Hibernate+JPA的多个数据库

java hibernate spring jpa multi-database

2022-09-01 12:10:36

我正在尝试配置Spring+ Hibernate + JPA以使用两个数据库（MySQL和MSSQL）。

我的数据源上下文.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"
 xsi:schemaLocation="http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
  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/util http://www.springframework.org/schema/util/spring-util-2.5.xsd"
 xmlns:p="http://www.springframework.org/schema/p" xmlns:tx="http://www.springframework.org/schema/tx"
 xmlns:util="http://www.springframework.org/schema/util">

 <!--
 Data Source config 
  -->
 <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
  destroy-method="close" p:driverClassName="${local.jdbc.driver}" p:url="${local.jdbc.url}"
  p:username="${local.jdbc.username}" p:password="${local.jdbc.password}">
 </bean>

 <bean id="dataSourceRemote" class="org.apache.commons.dbcp.BasicDataSource"
  destroy-method="close" p:driverClassName="${remote.jdbc.driver}"
  p:url="${remote.jdbc.url}" p:username="${remote.jdbc.username}"
  p:password="${remote.jdbc.password}" />

 <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"
  p:entity-manager-factory-ref="entityManagerFactory" />

 <!-- 
    JPA config   
    -->
 <tx:annotation-driven transaction-manager="transactionManager" />

 <bean id="persistenceUnitManager"
  class="org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager">
        <property name="persistenceXmlLocations">
   <list value-type="java.lang.String">
    <value>classpath*:config/persistence.local.xml</value>
    <value>classpath*:config/persistence.remote.xml</value>
   </list>
  </property>

  <property name="dataSources">
   <map>
    <entry key="localDataSource" value-ref="dataSource" />
    <entry key="remoteDataSource" value-ref="dataSourceRemote" />
   </map>
  </property>
  <property name="defaultDataSource" ref="dataSource" />
 </bean>

 <bean id="entityManagerFactory"
  class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
  <property name="jpaVendorAdapter">
   <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"
    p:showSql="true" p:generateDdl="true">
   </bean>
  </property>
  <property name="persistenceUnitManager" ref="persistenceUnitManager" />
<property name="persistenceUnitName" value="localjpa"/>
 </bean>

 <bean
  class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />

</beans>

每个持久性.xml都包含一个单元，如下所示：

<persistence-unit name="remote" transaction-type="RESOURCE_LOCAL">
  <properties>
   <property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.DefaultNamingStrategy" />
   <property name="hibernate.dialect" value="${remote.hibernate.dialect}" />
   <property name="hibernate.hbm2ddl.auto" value="${remote.hibernate.hbm2ddl.auto}" />
  </properties>
 </persistence-unit>

PersistenceUnitManager 导致以下异常：

无法解析对 Bean 'persistenceUnitManager' 的引用，同时设置 Bean 属性 'persistenceUnitManager';嵌套的异常是 org.springframework.beans.factory.BeanCreationException：创建在类路径资源 [config/datasource-context.xml] 中定义名为“persistenceUnitManager”的 bean 时出错： Bean 初始化失败;嵌套异常是 org.springframework.beans.TypeMismatchException：未能将类型 [java.util.ArrayList] 的属性值转换为属性 'persistenceXmlLocation' 的必需类型 [java.lang.String];嵌套异常是 java.lang.IllegalArgumentException：无法将属性 'persistenceXmlLocation' 的必需类型 [java.util.ArrayList] 的值转换为必需类型 [java.lang.String]：找不到匹配的编辑器或转换策略

如果只留下一个持久性.xml没有列表，每个工作正常，但我需要2个单位...

我还尝试在Spring+ Hibernate上下文中找到使用两个数据库的替代解决方案，因此我将不胜感激任何解决方案。

更改为后的新错误：persistenceXmlLocations

在 {classpath：config/persistence.local.xml， classpath：config/persistence.remote.xml} 中没有定义单个默认持久性单元

更新：

我添加了持久性UnitName，它可以工作，但只有一个单位，仍然需要帮助。

更新：

我更改了配置文件：数据源上下文.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"
    xsi:schemaLocation="http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
        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/util http://www.springframework.org/schema/util/spring-util-2.5.xsd"
    xmlns:p="http://www.springframework.org/schema/p" xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:util="http://www.springframework.org/schema/util">

    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
        destroy-method="close" p:driverClassName="${local.jdbc.driver}" p:url="${local.jdbc.url}"
        p:username="${local.jdbc.username}" p:password="${local.jdbc.password}">
    </bean>

    <bean id="dataSourceRemote" class="org.apache.commons.dbcp.BasicDataSource"
        destroy-method="close" p:driverClassName="${remote.jdbc.driver}"
        p:url="${remote.jdbc.url}" p:username="${remote.jdbc.username}"
        p:password="${remote.jdbc.password}">
    </bean>

    <bean
        class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor">
        <property name="defaultPersistenceUnitName" value="pu1" />
    </bean>

    <bean id="persistenceUnitManager"
        class="org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager">
        <property name="persistenceXmlLocation" value="${persistence.xml.location}" />
        <property name="defaultDataSource" ref="dataSource" /> <!-- problem -->
        <property name="dataSources">
            <map>
                <entry key="local" value-ref="dataSource" />
                <entry key="remote" value-ref="dataSourceRemote" />
            </map>
        </property>
    </bean>

    <bean id="entityManagerFactory"
        class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"
                p:showSql="true" p:generateDdl="true">
            </bean>
        </property>
        <property name="persistenceUnitManager" ref="persistenceUnitManager" />
        <property name="persistenceUnitName" value="pu1" />
        <property name="dataSource" ref="dataSource" />
    </bean>

    <bean id="entityManagerFactoryRemote"
        class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"
                p:showSql="true" p:generateDdl="true">
            </bean>
        </property>
        <property name="persistenceUnitManager" ref="persistenceUnitManager" />
        <property name="persistenceUnitName" value="pu2" />
        <property name="dataSource" ref="dataSourceRemote" />
    </bean>

    <tx:annotation-driven />

    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"
        p:entity-manager-factory-ref="entityManagerFactory" />


    <bean id="transactionManagerRemote" class="org.springframework.orm.jpa.JpaTransactionManager"
        p:entity-manager-factory-ref="entityManagerFactoryRemote" />

</beans>

持久性.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
                 http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
    version="1.0">

    <persistence-unit name="pu1" transaction-type="RESOURCE_LOCAL">
        <properties>
            <property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.DefaultNamingStrategy" />
            <property name="hibernate.dialect" value="${local.hibernate.dialect}" />
            <property name="hibernate.hbm2ddl.auto" value="${local.hibernate.hbm2ddl.auto}" />                          
        </properties>
    </persistence-unit>

    <persistence-unit name="pu2" transaction-type="RESOURCE_LOCAL">
        <properties>
            <property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.DefaultNamingStrategy" />
            <property name="hibernate.dialect" value="${remote.hibernate.dialect}" />
            <property name="hibernate.hbm2ddl.auto" value="${remote.hibernate.hbm2ddl.auto}" />
        </properties>
    </persistence-unit>

</persistence>

现在它构建了两个实体ManagerFactory，但两者都用于Microsoft SQL Server。

[main] INFO org.hibernate.ejb.Ejb3Configuration - Processing PersistenceUnitInfo [
    name: pu1
    ...]
[main] INFO org.hibernate.cfg.SettingsFactory - RDBMS: Microsoft SQL Server

[main] INFO org.hibernate.ejb.Ejb3Configuration - Processing PersistenceUnitInfo [
    name: pu2
    ...]
[main] INFO org.hibernate.cfg.SettingsFactory - RDBMS: Microsoft SQL Server (but must MySQL)

我建议，只使用dataSource，dataSourceRemote（没有替换）是行不通的。这是我的最后一个问题。

答案 1

您需要使用属性（请注意复数形式）而不是。它是一个字符串数组，因此它将从列表自动转换：persistenceXmlLocationspersistenceXmlLocation

<bean id="persistenceUnitManager"
      class="org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager">
  <property name="persistenceXmlLocations"><list>
    <value>classpath*:config/persistence.local.xml</value>
    <value>classpath*:config/persistence.remote.xml</value>
  </list></property>
  ...

更新（基于编辑）

您不指定属性。您必须明确地这样做，因为您正在定义多个持久性单元，并且必须知道要使用哪一个。entityManagerFactorypersistenceUnitNameentityManagerFactory

答案 2

贾斯汀，数字3可以用更标准的方式完成，如下所示：

在你的春季背景下：
```
<context:annotation-config />
```

在 Spring 管理的 DAO 中（请注意 unitName 属性）：

@PersistenceContext(unitName = "pu1"`) protected EntityManager entityManager;

通过这种方式，与名为“pu1”的持久性单元相对应的正确初始化的EntityManager将被注入相应的DAO中。