asked on

Problem with Beans

I am new to JSP, i m trying to build a simple application, using beans. This application is made with reference to Sun's Tutorials. I am using Tomcat to run JSP. The problem is with an error which i am not able to figure out. It says that the Bean class is not found, although its placed in the WEB-INF folder. I have used the package approach, but the error still persist. Here are the errors, first is the exception report and the secnod one is the root cause;

type Exception report

message Internal Server Error

description The server encountered an internal error (Internal Server Error) that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: NameHandler
      at org.apache.jasper.compiler.BeanRepository.getBeanType(BeanRepository.java:183)
      at org.apache.jasper.compiler.GetPropertyGenerator.generate(GetPropertyGenerator.java:102)
      at org.apache.jasper.compiler.JspParseEventListener$GeneratorWrapper.generate(JspParseEventListener.java:834)
      at org.apache.jasper.compiler.JspParseEventListener.generateAll(JspParseEventListener.java:241)
      at org.apache.jasper.compiler.JspParseEventListener.endPageProcessing(JspParseEventListener.java:197)
      at org.apache.jasper.compiler.Compiler.compile(Compiler.java:215)
      at org.apache.jasper.servlet.JspServlet.loadJSP(JspServlet.java:552)
      at org.apache.jasper.servlet.JspServlet$JspServletWrapper.loadIfNecessary(JspServlet.java:177)
      at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:189)
      at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:382)
      at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:474)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
      at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
      at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
      at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:190)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
      at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:246)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
      at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
      at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2343)
      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
      at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
      at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
      at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:468)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
      at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
      at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
      at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
      at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1012)
      at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:1107)
      at java.lang.Thread.run(Thread.java:536)

root cause

java.lang.ClassNotFoundException: NameHandler
      at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1394)
      at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1243)
      at org.apache.jasper.compiler.BeanRepository.getBeanType(BeanRepository.java:181)
      at org.apache.jasper.compiler.GetPropertyGenerator.generate(GetPropertyGenerator.java:102)
      at org.apache.jasper.compiler.JspParseEventListener$GeneratorWrapper.generate(JspParseEventListener.java:834)
      at org.apache.jasper.compiler.JspParseEventListener.generateAll(JspParseEventListener.java:241)
      at org.apache.jasper.compiler.JspParseEventListener.endPageProcessing(JspParseEventListener.java:197)
      at org.apache.jasper.compiler.Compiler.compile(Compiler.java:215)
      at org.apache.jasper.servlet.JspServlet.loadJSP(JspServlet.java:552)
      at org.apache.jasper.servlet.JspServlet$JspServletWrapper.loadIfNecessary(JspServlet.java:177)
      at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:189)
      at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:382)
      at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:474)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
      at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
      at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
      at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:190)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
      at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:246)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
      at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
      at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2343)
      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
      at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
      at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
      at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:468)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
      at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
      at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
      at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
      at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1012)
      at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:1107)
      at java.lang.Thread.run(Thread.java:536)

TimYates

> It says that the Bean class is not found, although its placed in the WEB-INF folder

is the class in:

WEB-INF/classes/your/package/NameHandler.class

?

It needs to be in WEB-INF/classes, not just WEB-INF

TimYates

Or, if it is in a jar, put the jar into

WEB-INF/lib

NadirMaroof

ASKER

ya i have followed the right path, its
E:\JSP Learning\Using Beans\WEB-INF\classes\hello\NameHandler.class

the package name is hello.

TimYates

and your tomcat context is set to:

E:\JSP Learning\Using Beans\

?

Can you try a directory without spaces in it? (Java doesn't like spaces in filenames as a general rule) :-(

If that doesn't help, can you post your bean code?

NadirMaroof

ASKER

yes my tomcat context is set to;
E:\JSPLearning

i have removed the spaces, UsingBeans is a folder inside JSPLearning, i have not mentioned UsingBeans in the context. My bean code is as follows.

package hello;

public class NameHandler{

private String username;

public NameHandler(){
      username=null;}

public void setUserName(String name){
      username = name;}

public String getUserName(){
      return username;}

}

TimYates

> i have not mentioned UsingBeans in the context

E:\JSP Learning\Using Beans\WEB-INF\classes\hello\NameHandler.class

should be:

E:\JSP Learning\WEB-INF\classes\hello\NameHandler.class

then (I think)

NadirMaroof

ASKER

oh sorry, i thought that if JSPLearning is mentioned in the context, then its enough, now i have placed the WEB-INF folder to;

E:\JSP Learning\WEB-INF\classes\hello\NameHandler.class

but the first error still persist,

type Exception report

message Internal Server Error

description The server encountered an internal error (Internal Server Error) that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: Cannot find any information on property 'username' in a bean of type 'hello.NameHandler'
      at org.apache.jasper.runtime.JspRuntimeLibrary.getReadMethod(JspRuntimeLibrary.java:702)
      at org.apache.jasper.compiler.GetPropertyGenerator.generate(GetPropertyGenerator.java:104)
      at org.apache.jasper.compiler.JspParseEventListener$GeneratorWrapper.generate(JspParseEventListener.java:834)
      at org.apache.jasper.compiler.JspParseEventListener.generateAll(JspParseEventListener.java:241)
      at org.apache.jasper.compiler.JspParseEventListener.endPageProcessing(JspParseEventListener.java:197)
      at org.apache.jasper.compiler.Compiler.compile(Compiler.java:215)
      at org.apache.jasper.servlet.JspServlet.loadJSP(JspServlet.java:552)
      at org.apache.jasper.servlet.JspServlet$JspServletWrapper.loadIfNecessary(JspServlet.java:177)
      at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:189)
      at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:382)
      at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:474)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
      at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
      at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
      at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:190)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
      at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:246)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
      at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
      at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2343)
      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
      at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
      at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
      at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:468)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
      at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
      at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
      at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
      at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
      at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1012)
      at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:1107)
      at java.lang.Thread.run(Thread.java:536)

TimYates

> but the first error still persist,

that's a different error, surely?

> Cannot find any information on property 'username' in a bean of type 'hello.NameHandler'

You have called it

"userName" in the bean, and (I'm guessing) "username" in the JSP ;-)

Tim

TimYates

> public void setUserName(String name){

...

> public String getUserName(){

See? Capital "N" in name for the get and set method ;-)

Tim

NadirMaroof

ASKER

hey, i had two errors, if u look at my first post. And i really dont understand that what difference does it make with capital N in the method name ;-)

can u plz elaborate a little, i have used "username" everywhere, which is an attribute of type String in my bean.

NadirMaroof

ASKER

sorry Tim, it worked, but still i would like u to explain why this has happened. the program is running fine now.

NadirMaroof

ASKER

and 'U' is also in caps, why its not making much effect ? why only 'N'

TimYates

when you use JSP to get an attribute (or set one) using JSP tags, it uses reflection to call the correct method name. So for getters and setters, if you have a String variable called

myVariable

then you need to write a method which looks like

public void getMyVariable()

and one which looks like

public String setMyVariable( String var )

Notice how you make the first letter after "get" or "set" capital.

So for "username", you need to write:

public String getUsername(){

and

public void setUsername(String name){

Notice, the capital "U" (as it is after "get" and "set"), but the lowercase "n", as you want to call your variable "username", NOT "userName"

Then,

<jsp:getProperty name="username" property="username"/>

will work :-)

> hey, i had two errors, if u look at my first post.

Yeah, both those errors are because tomcat couldn't find the "NameHandler" class... The error you posted just now, is because it cannot find the method "getUsername" (or setUsername), as you had a capital "N" in the method names

Hope this explains it a bit better!!

Tim

TimYates

Phew! What a lot of typing for 20 points ;-)

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TimYates

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NadirMaroof

ASKER

thank you Tim, you really helped me, well ya it was a bit for 20 points, but thanx anyways :-)

cheers

TimYates

No worries :-) Glad I could help :-)

Good luck with it!!

Tim