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SSH集成的java.lang.NullPointerException异常

JAVA学习网 2017-12-22 21:12:01 
在完成ssh集成的Struts2层的集成后，启动Tomcat后，出现了异常：
严重: ********** FATAL ERROR STARTING UP STRUTS-SPRING INTEGRATION **********
Looks like the Spring listener was not configured for your web app! 
Nothing will work until WebApplicationContextUtils returns a valid ApplicationContext.
You might need to add the following to web.xml: 
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
十二月 21, 2017 9:28:05 下午 com.opensymphony.xwork2.util.logging.commons.CommonsLogger error
严重: Dispatcher initialization failed
java.lang.NullPointerException
at com.opensymphony.xwork2.spring.SpringObjectFactory.getClassInstance(SpringObjectFactory.java:230)
......

在异常界面点SpringObjectFactory.java查看源码，在

   if (appContext.containsBean(className)) {

上设置断电，进行Debug，发现appContext的值为null。这是因为，我们在Spring中配置了Struts2，在项目启动后Struts自动去Spring容器中拿对象，而此时Spring并没有启动，所以要让Spring在服务器启动的时候也同时启动。需要在web.xml中配置

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

该监听器会在项目启动的时候同时启动Spring

在配置完成之后启动项目，有出现了

IOException parsing XML document from ServletContext resource [/WEB-INF/applicationContext.xml]的异常，很明显是配置文件的异常，系统没有加载到applicationContext.xml
org.springframework.beans.factory.BeanDefinitionStoreException: IOException parsing XML document from ServletContext resource [/WEB-INF/applicationContext.xml]; nested exception is java.io.FileNotFoundException: Could not open ServletContext resource [/WEB-INF/applicationContext.xml]
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:344)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:304)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:181)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:217)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:188)
    at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125)
    at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94)
    at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:129)
    at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:614)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:515)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:443)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:325)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5110)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5633)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1700)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1690)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.FileNotFoundException: Could not open ServletContext resource [/WEB-INF/applicationContext.xml]
    at org.springframework.web.context.support.ServletContextResource.getInputStream(ServletContextResource.java:141)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:330)
    ... 21 more

我们需要在web.xml中配置

<context-param>
　　<param-name>contextConfigLocation</param-name>
　　<param-value>classpath:applicationContext.xml</param-value>
</context-param>

这些内容告诉了listener applicationContext.xml的加载路径

 
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