applicationContext.xml的配置：（重点看红色部分）
<bean id="dataSource" class="org.logicalcobwebs.proxool.ProxoolDataSource" destroy-method="close">
<property name="driver">
<value>${datasource.connection.driver_class}</value>
</property>
<property name="driverUrl">
<value>${datasource.connection.url}</value>
</property>
<property name="user">
<value>${datasource.connection.username}</value>
</property>
<property name="password">
<value>${datasource.connection.password}</value>
</property>
<property name="alias">
<value>${datasource.connection.alias}</value>
</property>
<property name="prototypeCount">
<value>${datasource.connection.prototypeCount}</value>
</property>
<property name="maximumConnectionCount">
<value>${datasource.connection.maximumConnectionCount}</value>
</property>
<property name="minimumConnectionCount">
<value>${datasource.connection.minimumConnectionCount}</value>
</property>
<property name="houseKeepingTestSql">
<value>${datasource.connection.houseKeepingTestSql}</value>
</property>
<property name="testBeforeUse">
<value>${datasource.connection.testBeforeUse}</value>
</property>
<property name="testAfterUse">
<value>${datasource.connection.testAfterUse}</value>
</property>
<property name="trace">
<value>${datasource.connection.trace}</value>
</property>
</bean>
数据库配置的文件：
datasource2.connection.url=jdbc:mysql://IP:3306/test?useUnicode=true&characterEncoding=gbk
datasource2.connection.driver_class=com.mysql.jdbc.Driver
这样配置会出现如下错误：
严重: Context initialization failed
org.springframework.beans.factory.BeanDefinitionStoreException: Invalid bean definition with name 'dataSource' defined in ServletContext resource [/WEB-INF/config/applicationContext.xml]: Could not resolve placeholder 'jdbc.driver'
at org.springframework.beans.factory.config.PropertyPlaceholderConfigure
r.processProperties(PropertyPlaceholderConfigurer.java:272)
at org.springframework.beans.factory.config.PropertyResourceConfigurer.p
ostProcessBeanFactory(PropertyResourceConfigurer.java:75)
at org.springframework.context.support.AbstractApplicationContext.invoke
BeanFactoryPostProcessors(AbstractApplicationContext.java:663)
at org.springframework.context.support.AbstractApplicationContext.invoke
BeanFactoryPostProcessors(AbstractApplicationContext.java:638)
at org.springframework.context.support.AbstractApplicationContext.refres
h(AbstractApplicationContext.java:407)
at org.springframework.web.context.ContextLoader.createWebApplicationCon
text(ContextLoader.java:276)
at org.springframework.web.context.ContextLoader.initWebApplicationConte
xt(ContextLoader.java:197)
at org.springframework.web.context.ContextLoaderListener.contextInitiali
zed(ContextLoaderListener.java:47)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContex
t.java:4323)
at org.apache.catalina.core.StandardContext.startInternal(StandardContex
t.java:4771)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:138)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase
.java:785)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:76
3)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:558)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.jav
a:1124)
at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.j
ava:1047)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:542
)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1390)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java
:355)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(Lifecycl
eSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBa
se.java:89)
at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:31
2)
at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:29
2)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.ja
va:998)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java
:772)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:138)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.ja
va:990)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.
java:275)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:138)
at org.apache.catalina.core.StandardService.startInternal(StandardServic
e.java:424)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:138)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.
java:648)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:138)
at org.apache.catalina.startup.Catalina.start(Catalina.java:576)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:415)
2010-7-27 11:18:35 org.apache.catalina.core.StandardContext startInternal
解决办法:将配置文件中的datasource2换成datasource就可以了