Error description of the value mechanism of El Expression: at Javax.el.beanelresolver$beanproperties.get (beanelresolver.java:237)

First post the error message:

December 14, 2017 10:54:42afternoon Org.apache.catalina.core.ApplicationDispatcher InvokeSEVERE:Servlet.service () forservlet JSP threw exceptionJavax.el.PropertyNotFoundException:Property ' Classroomid 'Not  found on type cn.toohoo.classroom.dto.Classroom at Javax.el.beanelresolver$beanproperties.get ( Beanelresolver.java:237) at javax.el.beanelresolver$beanproperties.access$(beanelresolver.java:214) at Javax.el.BeanELResolver.property (Beanelresolver.java:325) at Javax.el.BeanELResolver.getValue (Beanelresolver.java:85) at Org.apache.jasper.el.JasperELResolver.getValue (Jasperelresolver.java:104) at Org.apache.el.parser.AstValue.getValue (Astvalue.java:183) at Org.apache.el.ValueExpressionImpl.getValue (Valueexpressionimpl.java:185) at Org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate (Pagecontextimpl.java:1026) at org.apache.jsp.admin.classroom.listclassroom_jsp._jspx_meth_c_005fforeach_005f0 (Listclassroom_jsp.java: 356) at org.apache.jsp.admin.classroom.listclassroom_jsp._jspx_meth_c_005fif_005f0 (Listclassroom_jsp.java:314) at Org.apache.jsp.admin.classroom.listclassroom_jsp._jspservice (Listclassroom_jsp.java:218) at Org.apache.jasper.runtime.HttpJspBase.service (Httpjspbase.java:70) at Javax.servlet.http.HttpServlet.service (Httpservlet.java:728) at Org.apache.jasper.servlet.JspServletWrapper.service (Jspservletwrapper.java:432) at Org.apache.jasper.servlet.JspServlet.serviceJspFile (Jspservlet.java:390) at Org.apache.jasper.servlet.JspServlet.service (Jspservlet.java:334) at Javax.servlet.http.HttpServlet.service (Httpservlet.java:728) at Org.apache.catalina.core.ApplicationFilterChain.internalDoFilter (Applicationfilterchain.java:305) at Org.apache.catalina.core.ApplicationFilterChain.doFilter (Applicationfilterchain.java:210) at Org.apache.catalina.core.ApplicationDispatcher.invoke (Applicationdispatcher.java:749) at Org.apache.catalina.core.ApplicationDispatcher.processRequest (Applicationdispatcher.java:487) at Org.apache.catalina.core.ApplicationDispatcher.doForward (Applicationdispatcher.java:412) at Org.apache.catalina.core.ApplicationDispatcher.forward (Applicationdispatcher.java:339) at Cn.toohoo.classroom.servlet.ClassroomServlet.listClassroom (Classroomservlet.java:194) at Sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method) at Sun.reflect.NativeMethodAccessorImpl.invoke (Nativemethodaccessorimpl.java:57) at Sun.reflect.DelegatingMethodAccessorImpl.invoke (Delegatingmethodaccessorimpl.java:43) at Java.lang.reflect.Method.invoke (Method.java:601) at Cn.toohoo.baseservlet.BaseServlet.service (Baseservlet.java:44) at Javax.servlet.http.HttpServlet.service (Httpservlet.java:728) at Org.apache.catalina.core.ApplicationFilterChain.internalDoFilter (Applicationfilterchain.java:305) at Org.apache.catalina.core.ApplicationFilterChain.doFilter (Applicationfilterchain.java:210) at Org.apache.catalina.core.StandardWrapperValve.invoke (Standardwrappervalve.java:222) at Org.apache.catalina.core.StandardContextValve.invoke (Standardcontextvalve.java:123) at Org.apache.catalina.authenticator.AuthenticatorBase.invoke (Authenticatorbase.java:502) at Org.apache.catalina.core.StandardHostValve.invoke (Standardhostvalve.java:171) at Org.apache.catalina.valves.ErrorReportValve.invoke (Errorreportvalve.java:99) at Org.apache.catalina.valves.AccessLogValve.invoke (Accesslogvalve.java:953) at Org.apache.catalina.core.StandardEngineValve.invoke (Standardenginevalve.java:118) at Org.apache.catalina.connector.CoyoteAdapter.service (Coyoteadapter.java:408) at Org.apache.coyote.http11.AbstractHttp11Processor.process (Abstracthttp11processor.java:1023) at Org.apache.coyote.abstractprotocol$abstractconnectionhandler.process (Abstractprotocol.java:48X) at Org.apache.tomcat.util.net.jioendpoint$socketprocessor.run (Jioendpoint.java:310) at Java.util.concurrent.ThreadPoolExecutor.runWorker (Threadpoolexecutor.java:1110) at Java.util.concurrent.threadpoolexecutor$worker.run (Threadpoolexecutor.java:603) at Java.lang.Thread.run (Thread.java:722) java.lang.reflect.InvocationTargetException at Sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method) at Sun.reflect.NativeMethodAccessorImpl.invoke (Nativemethodaccessorimpl.java:57) at Sun.reflect.DelegatingMethodAccessorImpl.invoke (Delegatingmethodaccessorimpl.java:43) at Java.lang.reflect.Method.invoke (Method.java:30T) at Cn.toohoo.baseservlet.BaseServlet.service (Baseservlet.java:44) at Javax.servlet.http.HttpServlet.service (Httpservlet.java:728) at Org.apache.catalina.core.ApplicationFilterChain.internalDoFilter (Applicationfilterchain.java:305) at Org.apache.catalina.core.ApplicationFilterChain.doFilter (Applicationfilterchain.java:210) at Org.apache.catalina.core.StandardWrapperValve.invoke (Standardwrappervalve.java:222) at Org.apache.catalina.core.StandardContextValve.invoke (Standardcontextvalve.java:123) at Org.apache.catalina.authenticator.AuthenticatorBase.invoke (Authenticatorbase.java:502) at Org.apache.catalina.core.StandardHostValve.invoke (Standardhostvalve.java:171) at Org.apache.catalina.valves.ErrorReportValve.invoke (Errorreportvalve.java:99) at Org.apache.catalina.valves.AccessLogValve.invoke (Accesslogvalve.java:953) at Org.apache.catalina.core.StandardEngineValve.invoke (Standardenginevalve.java:118) at Org.apache.catalina.connector.CoyoteAdapter.service (Coyoteadapter.java:408) at Org.apache.coyote.http11.AbstractHttp11Processor.process (Abstracthttp11processor.java:1023) at Org.apache.coyote.abstractprotocol$abstractconnectionhandler.process (Abstractprotocol.java:589) at Org.apache.tomcat.util.net.jioendpoint$socketprocessor.run (Jioendpoint.java:310) at Java.util.concurrent.ThreadPoolExecutor.runWorker (Threadpoolexecutor.java:1110) at Java.util.concurrent.threadpoolexecutor$worker.run (Threadpoolexecutor.java:30V) at Java.lang.Thread.run (Thread.java:722) caused By:org.apache.jasper.JasperException:An exception occurred processing JSP page/admin/classroom/listclassroom.jsp at line 131128: <c:foreach var= "Classroom" items= "${r                                      EquestScope.pageBean.pageData} "varstatus=" vs ">129: <tr>130: <td>${vs.count}</td>131: <td>${classroom.class                                      Roomid}</td>132: <td>${classroom.classroomname}</td>133: <td>${classroom.classroomtype}</td>134: &lt ; Td>${classroom.classroomcapacity}</td>stacktrace:at org.apache.jasper.servlet.JspServletWrapper.handleJspException (Jspservletwrapper.java:568) at Org.apache.jasper.servlet.JspServletWrapper.service (Jspservletwrapper.java:470) at Org.apache.jasper.servlet.JspServlet.serviceJspFile (Jspservlet.java:390) at Org.apache.jasper.servlet.JspServlet.service (Jspservlet.java:334) at Javax.servlet.http.HttpServlet.service (Httpservlet.java:728) at Org.apache.catalina.core.ApplicationFilterChain.internalDoFilter (Applicationfilterchain.java:305) at Org.apache.catalina.core.ApplicationFilterChain.doFilter (Applicationfilterchain.java:210) at Org.apache.catalina.core.ApplicationDispatcher.invoke (Applicationdispatcher.java:749) at Org.apache.catalina.core.ApplicationDispatcher.processRequest (Applicationdispatcher.java:487) at Org.apache.catalina.core.ApplicationDispatcher.doForward (Applicationdispatcher.java:412) at Org.apache.catalina.core.ApplicationDispatcher.forward (Applicationdispatcher.java:339) at Cn.toohoo.classroom.servlet.ClassroomServlet.listClassroom (Classroomservlet.java:194)    ... 22morecaused By:javax.el.PropertyNotFoundException:Property' Classroomid 'Not found on type cn.toohoo.classroom.dto.Classroom at Javax.el.beanelresolver$beanproperties.get (beanelresolver . Java:237) at javax.el.beanelresolver$beanproperties.access$(beanelresolver.java:214) at Javax.el.BeanELResolver.property (Beanelresolver.java:325) at Javax.el.BeanELResolver.getValue (Beanelresolver.java:85) at Org.apache.jasper.el.JasperELResolver.getValue (Jasperelresolver.java:104) at Org.apache.el.parser.AstValue.getValue (Astvalue.java:183) at Org.apache.el.ValueExpressionImpl.getValue (Valueexpressionimpl.java:185) at Org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate (Pagecontextimpl.java:1026) at org.apache.jsp.admin.classroom.listclassroom_jsp._jspx_meth_c_005fforeach_005f0 (Listclassroom_jsp.java: 356) at org.apache.jsp.admin.classroom.listclassroom_jsp._jspx_meth_c_005fif_005f0 (Listclassroom_jsp.java:314) at Org.apache.jsp.admin.classroom.listclassroom_jsp._jspservice (Listclassroom_jsp.java:218) at Org.apache.jasper.runtime.HttpJspBase.service (Httpjspbase.java:70) at Javax.servlet.http.HttpServlet.service (Httpservlet.java:728) at Org.apache.jasper.servlet.JspServletWrapper.service (Jspservletwrapper.java:432)    ... More

Then follow the error message

Javax.el.PropertyNotFoundException:Property ' Classroomid ' not found on type Cn.toohoo.classroom.dto.Classroom

To classroom entity class lookup

    PrivateString Classroomid; PrivateString Classroomname; PrivateString Classroomtype; PrivateString classroomcapacity;  PublicString Getclassroomid () {returnClassroomid; }     Public voidSetclassroomid (String classroomid) { This. Classroomid =Classroomid; }     PublicString Getclassroomname () {returnClassroomname; }     Public voidsetclassroomname (String classroomname) { This. Classroomname =Classroomname; }

is the existence of the private String classroomid; Yes, and then wondering, then various modifications,

。。。。。。。。。。。。。。。

Finally, go back to the JSP

<c:if test= "${not Empty RequestScope.pageBean.pageData}" > <c:foreach var= "Classroom" items=                                     "${requestscope.pagebean.pagedata}" varstatus= "vs" > <tr> <td>${vs.count}</td> <td>${classroom.classroomid}&lt                                     ;/td> <td>${classroom.classroomname}</td> <td>${classroom.classroomtype}</td> <td>${classroom.classro Omcapacity}</td> <td> <a HRE f= "<c:url value= '/classroomservlet?method=queryclassroom&classroomid=${classroom.classroomid} '/>" > Modify </a> <a href= "<c:url value="/classroomservlet?method=deleteclassroo M&classroomid=${classroom.clasSroomid} '/> ' > Delete </a> </td> </ Tr> </c:forEach> </c:if>

Simply remove the line containing the ${classroom.classroomid}

Change into

 <c:if  test= "${not empty RequestScope.pageBean.pageD ATA} "> <c:foreach var=" Classroom "items=" ${requestscope.pagebean.pagedata} "varstatus= "vs" > <tr> <td>${vs.count}</td>                                                                          ; <td>${classroom.classroomname}</td> <td>${classroom.classroomtype}                                     </td> <td>${classroom.classroomcapacity}</td>                                   <td> </td> </tr> </c:forEach> </c:
   
    if ; 
   

A visit to the webpage passed

Why ${classroom.classroomname} can pass through and ${classroom.classroomid} but not go through, continue to check classroom entity class

Go back to JSP to change ${classroom.classroomid} to ${classroom.classroomid}

Redeploy, access through, guys

Summary: MyEclipse error is to be very serious analysis, and this mistake let me to the El expression value method to understand the deeper, is through the public method to take the value of the external, so say the name must be correct, at the same time for this myeclipse generated code I really depressed burst, serious inspection! Learn lessons.

Error description of the value mechanism of El Expression: at Javax.el.beanelresolver$beanproperties.get (beanelresolver.java:237)