webwork错误提示空指针异常和unknown source_at com.isoftstone.fwk.web.filter.dwcallbackfilter.-优快云博客

本文介绍了一种在使用Log4j记录日志时遇到的空指针异常问题及其解决方法。问题出现在尝试获取空对象的属性时，并通过检查和确保对象非空来解决。

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场景一:

1.系统提示空指针异常

2.log4j文件提示 unkown source

解决方法:

logger.debug("saveParty[methods]---[variable]photo.getId() : " + photo.getId());

发现是系统在输出log4j信息时,需要取得photo这个对象的某个属性,但是photo这个对象是空,所以出现"错误提示未知的源"

错误信息如下:

java.lang.NullPointerException
        at com.marryfive.console.party.business.service.impl.PartyServiceImpl.sa
veParty(Unknown Source)
        at com.marryfive.console.party.presentation.action.PartyAction.saveParty
(Unknown Source)
        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:585)
        at com.opensymphony.xwork.DefaultActionInvocation.invokeAction(DefaultAc
tionInvocation.java:358)
        at com.opensymphony.xwork.DefaultActionInvocation.invokeActionOnly(Defau
ltActionInvocation.java:218)
        at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionIn
vocation.java:192)
        at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(Around
Interceptor.java:31)
        at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionIn
vocation.java:190)
        at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(Around
Interceptor.java:31)
        at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionIn
vocation.java:190)
        at com.marryfive.common.interceptor.HibernateInterceptor.intercept(Hiber
nateInterceptor.java:96)
        at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionIn
vocation.java:190)
        at com.opensymphony.webwork.interceptor.FileUploadInterceptor.intercept(
FileUploadInterceptor.java:238)
        at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionIn
vocation.java:190)
        at com.opensymphony.xwork.DefaultActionProxy.execute(DefaultActionProxy.
java:116)
        at com.opensymphony.webwork.dispatcher.DispatcherUtils.serviceAction(Dis
patcherUtils.java:225)
        at com.opensymphony.webwork.dispatcher.FilterDispatcher.doFilter(FilterD
ispatcher.java:202)
        at com.marryfive.console.power.presentation.dispatcher.PermissionFilterD
ispatcher.doFilter(Unknown Source)
        at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterCha
in.java:70)
        at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain
.java:178)
        at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocatio
n.java:229)
        at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:268
)
        at com.caucho.server.port.TcpConnection.run(TcpConnection.java:389)
        at com.caucho.util.ThreadPool.runTasks(ThreadPool.java:507)
        at com.caucho.util.ThreadPool.run(ThreadPool.java:433)
        at java.lang.Thread.run(Thread.java:595)