Spring dataSource bean定义失败

Question

我正在尝试使用Spring的JdbcTemplate来简化我在Tomcat中部署并连接到Postgres的Java Web服务中的DAO.

我正在关注Spring的文档,我正在尝试在应用程序上下文文件中配置DataSource,如下所示:

<?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:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd">

  <context:component-scan base-package="com.manta" />

  <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
    <property name="driverClassName" value="${driverClassName}"/>
    <property name="url" value="${url}"/>
    <property name="username" value="${username}"/>
    <property name="password" value="${password}"/>
  </bean>

  <context:property-placeholder location="/WEB-INF/db.properties"/>

</beans>

我db.properties在适当的地方有以下文件:

driverClassName=org.postgresql.Driver 
url=jdbc:postgresql://pgprod.ecnext.com:5432/manta
username=my_user_name
password=my_password

当我尝试部署时,我发现以下堆栈跟踪catalina.out:

SEVERE: Context initialization failed
org.springframework.beans.factory.BeanDefinitionStoreException: 
Invalid bean definition with name 'dataSource' defined in ServletContext resource [/WEB-INF/context.xml]: 
Could not resolve placeholder 'driverClassName'
    at org.springframework.beans.factory.config.PlaceholderConfigurerSupport.doProcessProperties(PlaceholderConfigurerSupport.java:209)
    at org.springframework.beans.factory.config.PropertyPlaceholderConfigurer.processProperties(PropertyPlaceholderConfigurer.java:220)
    at org.springframework.beans.factory.config.PropertyResourceConfigurer.postProcessBeanFactory(PropertyResourceConfigurer.java:84)
    at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:681)
    at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:656)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:446)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:385)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:284)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:111)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4765)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5260)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:866)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:842)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:615)
    at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:958)
    at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1599)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
    at java.util.concurrent.FutureTask.run(FutureTask.java:166)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at java.lang.Thread.run(Thread.java:679)

事情不是问题:

1. 该db.properties文件位于正确的位置.
2. 其中的凭据db.properties是正确的,可以手动读取以连接到数据库.
3. context.xmlContextLoaderListener正在找到该文件,我可以注入其他依赖项.

我非常感谢任何可能导致这种情况的建议.我使用的是Spring 3.1.1和Tomcat 7.0.26.

Answer 1

你<context:property-placeholder ... >的项目中可能有多个,每个都创建了一个底层对象的新实例,并且是痛苦的通道......

我更喜欢使用以下声明来加载属性文件:

<bean id="propertyConfigurer"     class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="locations">
        <list>
            <value>classpath:db-config.properties</value>
        </list>
    </property>
    <property name="ignoreUnresolvablePlaceholders" value="true" />
</bean>