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Web Component Certification (OCEJWCD)

Page can't displayed - problem of configuring error location with servlet name in DD

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posted 17 years ago

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I am learning how to set to set servlet name in the location of
<error-page> in web.xml, I do not why I get page 'Page Can not displayed ' when I invoked
http://localhost:8080/myWeb/practicse/error2

Here's my snippet

========== ErrorTest2.java
public void doGet( HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException
{
System.out.println("In ErrorTest2 class, throw ServletException exception.");
throw new IOException("wrong match");
}

========== MyErrorServlet2.java
public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException
{
String msg = (String) req.getAttribute ("javax.servlet.error.message");
System.out.println(" my error message is: " + msg );
PrintWriter out = res.getWriter();
res.setContentType("text/html");
out.println("<html><body>");
out.println("<br>Ha, error message is: " + msg );
out.println("</body></html>");

}
========== web.xml ================
<servlet>
<servlet-name>ET202</servlet-name>
<servlet-class>coreservlets.ErrorTest2</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ET202</servlet-name>
<url-pattern>/practicse/error2</url-pattern>
</servlet-mapping>
<error-page>
<exception-type>java.io.IOException</exception-type>
<location>/servlet/MyErrorServlet2</location> 
</error-page>
<servlet>
<servlet-name>MyErrorServlet2</servlet-name>
<servlet-class>coreservlets.MyErrorServlet2</servlet-class>
</servlet>
=============

Anybody can help?

Thanks in advance!

Sergio Tridente

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Posts: 329

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posted 17 years ago

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I think you are missing the servlet-mapping for MyErrorServlet2. Try adding:

<servlet-mapping>
<servlet-name>MyErrorServlet2</servlet-name>
<url-pattern>/servlet/MyErrorServlet2</url-pattern>
</servlet-mapping>

SCJP 1.4 (88%) - SCJP 5.0 Upgrade (93%) - SCWCD 1.4 (97%) - SCBCD 5.0 (98%)

Grace Yang

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posted 17 years ago

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It's still not working withe servelt mapping.

I am interested in this questions too. However | don't why:-(

Atul Sawant

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posted 17 years ago

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Try to make a jsp page and use it as an error page instead of using a servlet and check if it is going well.

I think generally it practised to have an error page NOT to be a servlet.

Mission SCWCD. Mission SCJP Complete: SCJP 1.4 - 91%

Grace Yang

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posted 17 years ago

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Using a jsp page seems no problem.

But what's wrong inside the web.xml causing '.. can not displayed page'??

Anyboby know?

Sergio Tridente

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posted 17 years ago

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I tried it myself and it works just fine.

Here is a copy of my web.xml:

I changed the names a little, but in the end it the same web.xml.

SCJP 1.4 (88%) - SCJP 5.0 Upgrade (93%) - SCWCD 1.4 (97%) - SCBCD 5.0 (98%)

Grace Yang

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posted 17 years ago

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I know it's working using a jsp page, but I am interested in knowing technically how to put correct servlet name inside <location> .. </location> to display the error contents inside the servlet.

I'd like to know what's wrong in the original Tiffny's posting of using a servlet in the <location> to handle the error?

thanks

Tiffiny Yang

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posted 17 years ago

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Any body knows MyErrorServlet2 servelt is invoked, but browser gives me '..can not be displayed'?

Thanks

Mirko Bonasorte

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posted 17 years ago

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Using JBoss and jsp as error pages, I discovered it uses RequestDispatcher.forward() to reach the error page, which should work with any web resource (considering that JBoss internally uses Tomcat 4.1, maybe it's the same with Apache tomcat standalone).
However, I'm not sure but I seem to remember that it's not a mandatory behaviour: the Application Server may send a 'sendRedirect()' to the client.
Can your browser directly access to your error page?

Mirko Bonasorte

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I tried to use a servlet as an error page and everything went ok.

----> web.xml:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<servlet>
<servlet-name>Schiop</servlet-name>
<servlet-class>myservlet.Schiop</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>Schiop</servlet-name>
<url-pattern>/schiop/*</url-pattern>
</servlet-mapping>

<servlet>
<servlet-name>ErrorManager</servlet-name>
<servlet-class>myservlet.ErrorManager</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>ErrorManager</servlet-name>
<url-pattern>/error/*</url-pattern>
</servlet-mapping>
<error-page>
<exception-type>java.io.IOException</exception-type>
<location>/error</location>
</error-page>
</web-app>
<---- web.xml

----> ErrorManager.java:

package myservlet;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

public class ErrorManager extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
PrintWriter out = res.getWriter();

out.println("<html><body>pagina di errore</body></html>");
}
}
<---- ErrorManager.java

----> Schiop.java
package myservlet;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

public class Schiop extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
throw new IOException("Tonka!");
}
}
<---- Schiop.java

Deployment structure:

tomcat/webapps/prova/WEB-INF/web.xml
tomcat/webapps/prova/WEB-INF/classes/ErrorManager.class
tomcat/webapps/prova/WEB-INF/classes/Schiop.class

Tiffiny Yang

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Posts: 124

posted 17 years ago

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Thanks Mirko Bonasorte !!

I got clue from your post. I missed servlet mapping part which causing '.. website can not be displayed.'

It works now, I feel great, thanks all bodies who replied agian.

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