Throwing custom exception in servlet

Question

I want to throw a custom exception , somewhat like the following, from a servlet whenever some specific problem occurs.

public class CustomException extends Throwable {

    private String[] errArray;

    public CustomException(String[] errArray){
        this.errArray = errArray;
    }

    public String[] getErrors(){
        return errArray;
    }

}

And then when this exception is thrown I want to redirect the user to a specific error page.

<error-page>
    <exception-type>com.example.CustomException</exception-type>
    <location>/WEB-INF/jsp/errorPage.jsp</location>
</error-page>

Here is the error page, I want to use the exception implicit object.

<%@ page isErrorPage="true" %>
<%@ taglib prefix="my" tagdir="/WEB-INF/tags" %>
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1" %>

<my:head title="Error"></my:head>
<body>
    <% String errArray = exception.getErrors(); %>
</body>
</html>

Now the problem occurs when I go to add CustomException in throws declaration of the servlet's doGet method. I get the following error:

Exception CustomException is not compatible with throws clause in HttpServlet.doGet(HttpServletRequest, HttpServletResponse)

Now how can I overcome the problem? Is it even possible to custom exception like this & forward to error page when It is thrown? Or is there any other way? Thanks in advance :)

Answer 1

HttpServlet class doGet throws ServletException as declared below:

    protected void doGet(HttpServletRequest req,
                 HttpServletResponse resp)
          throws ServletException,
                 java.io.IOException

Please make your CustomException to extend ServletException to comply with the method specification.

EDIT: In your error.jsp, get the errors as:

<% String[] errArray = null; 
  if(exception instanceof CustomException) {
     errArray = (CustomException)exception.getErrors();
  } 
%>

Please note: It returns String[]

Throwing custom exception in servlet

Question

1 answers

solution1
4 ACCPTED 2012-11-08 05:06:54

Throwing custom exception in servlet

Question

1 answers

solution1 4 ACCPTED 2012-11-08 05:06:54

solution1
4 ACCPTED 2012-11-08 05:06:54