Target Unreachable, identifier '' resolved to null

2013-4-3 10:27:31 com.sun.faces.lifecycle.ProcessValidationsPhase execute
警告: /contentPages/basicManage/customer.xhtml @30,71 value="#{CustomerBean.queryParams.name}": Target Unreachable, identifier 'CustomerBean' resolved to null
javax.el.PropertyNotFoundException: /contentPages/basicManage/customer.xhtml @30,71 value="#{CustomerBean.queryParams.name}": Target Unreachable, identifier 'CustomerBean' resolved to null
    at com.sun.faces.facelets.el.TagValueExpression.getType(TagValueExpression.java:100)
    at org.primefaces.renderkit.InputRenderer.findImplicitConverter(InputRenderer.java:170)
    at org.primefaces.renderkit.InputRenderer.findConverter(InputRenderer.java:190)
    at org.primefaces.renderkit.InputRenderer.getConvertedValue(InputRenderer.java:196)
    at javax.faces.component.UIInput.getConvertedValue(UIInput.java:1030)
    at javax.faces.component.UIInput.validate(UIInput.java:960)
    at javax.faces.component.UIInput.executeValidate(UIInput.java:1233)
    at javax.faces.component.UIInput.processValidators(UIInput.java:698)
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
    at org.primefaces.component.panel.Panel.processValidators(Panel.java:293)
    at javax.faces.component.UIForm.processValidators(UIForm.java:253)
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
    at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1172)
    at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:76)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:79)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.sy.filters.EncodingFilter.doFilter(EncodingFilter.java:28)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.sy.utils.SecurityFilter.doFilter(SecurityFilter.java:68)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:619)

上面是我今天遇到的错误，意思是“通过bean名称找不到相应的受管bean”；找了好一阵都不知道哪里错了，其实这是个低级的错误。现在记录下来以免日后再犯，顺带帮助下后来的孩子们。我注解的ManageBean的名字是customerBean,但是我在页面中调用的时候错误的写成CustomerBean。导致出现这个错误

同时也遇到一个类似这样的错误（这里的代码仅供研究）：

javax.servlet.ServletException: /resume.jsp(19,2) '#{userBean.userResume.name }' Target Unreachable, 'userResume' returned null

javax.faces.webapp.FacesServlet.service(FacesServlet.java:606)

主要是因为在faces-config.xml中对应的managed bean配置中，没有把userResume 属性定义出来。


还会出现value="#{userBean.userResume.name }": Target Unreachable, 'userResume ' returned null

主要是因为在Backing Bean的getUserResume方法中，直接返回了userResume，没有判断user是否为空，为空则无法给它的属性赋值炒作，需要new一个出来：public UserResume getUserResume() {if(userResume==null)userResume = new UserResume();return userResume;}