name.martingeisse.admin.application.wicket.ExceptionMapper.java Source code

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Here is the source code for name.martingeisse.admin.application.wicket.ExceptionMapper.java

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/**
 * Copyright (c) 2011 Martin Geisse
 *
 * This file is distributed under the terms of the MIT license.
 */

package name.martingeisse.admin.application.wicket;

import name.martingeisse.common.util.ParameterUtil;

import org.apache.log4j.Logger;
import org.apache.wicket.Application;
import org.apache.wicket.DefaultExceptionMapper;
import org.apache.wicket.Page;
import org.apache.wicket.core.request.handler.IPageRequestHandler;
import org.apache.wicket.core.request.handler.PageProvider;
import org.apache.wicket.core.request.handler.RenderPageRequestHandler;
import org.apache.wicket.request.IRequestHandler;
import org.apache.wicket.request.Request;
import org.apache.wicket.request.component.IRequestablePage;
import org.apache.wicket.request.cycle.RequestCycle;
import org.apache.wicket.request.http.WebRequest;
import org.apache.wicket.request.http.handler.ErrorCodeRequestHandler;
import org.apache.wicket.settings.IExceptionSettings;
import org.apache.wicket.settings.IExceptionSettings.UnexpectedExceptionDisplay;

/**
 * This class maps exceptions to error pages. It extends the default exception
 * mapper from Wicket to add specialized error pages for specific exceptions
 * (only when in debug mode). The goal is to simplify finding the problem
 * that causes the exception. To avoid over-simplification, all specialized
 * error pages contain the same information as Wicket's exception page
 * at the bottom (including highlighted markup and the full exception
 * stack trace).
 */
public class ExceptionMapper extends DefaultExceptionMapper {

    /**
     * the logger
     */
    @SuppressWarnings("unused")
    private static Logger logger = Logger.getLogger(ExceptionMapper.class);

    /* (non-Javadoc)
     * @see org.apache.wicket.DefaultExceptionMapper#map(java.lang.Exception)
     */
    @Override
    public IRequestHandler map(final Exception e) {
        ParameterUtil.ensureNotNull(e, "e");
        try {
            final IRequestHandler result = internalMap(e);
            if (result == null) {
                // super.map will log the exception
                return super.map(e);
            } else {
                // log the exception here
                logger.error("Unexpected error occurred", e);
                return result;
            }
        } catch (final RuntimeException e2) {
            logger.error("nested exception in ExceptionMapper: " + e2.getMessage(), e2);
            return new ErrorCodeRequestHandler(500);
        }
    }

    /**
     * 
     */
    private IRequestHandler internalMap(final Exception e) {

        // we cannot handle AJAX exceptions, so delegate to the parent class
        final Request request = RequestCycle.get().getRequest();
        if (request instanceof WebRequest) {
            if (((WebRequest) request).isAjax()) {
                return null;
            }
        }

        // our special handling is only for debug mode
        final UnexpectedExceptionDisplay unexpectedExceptionDisplay = Application.get().getExceptionSettings()
                .getUnexpectedExceptionDisplay();
        if (!IExceptionSettings.SHOW_EXCEPTION_PAGE.equals(unexpectedExceptionDisplay)) {
            return null;
        }

        // extract the original cause since that is mostly relevant when finding a specialized error page
        Throwable originalCause = e;
        while (originalCause.getCause() != null) {
            originalCause = originalCause.getCause();
        }

        // handle some known exceptions
        /*
        if (originalCause instanceof UnknownEntityException) {
           return createPageRequestHandler(new UnknownEntityErrorPage(e, (UnknownEntityException)originalCause, extractCurrentPage()));
        }
        */

        // delegate all others to the parent class
        return null;

    }

    /**
     * 
     */
    @SuppressWarnings("unused")
    private Page extractCurrentPage() {
        final RequestCycle requestCycle = RequestCycle.get();
        IRequestHandler handler = requestCycle.getActiveRequestHandler();
        if (handler == null) {
            handler = requestCycle.getRequestHandlerScheduledAfterCurrent();
        }
        if (handler instanceof IPageRequestHandler) {
            final IPageRequestHandler pageRequestHandler = (IPageRequestHandler) handler;
            return (Page) pageRequestHandler.getPage();
        }
        return null;
    }

    /**
     * 
     */
    @SuppressWarnings("unused")
    private RenderPageRequestHandler createPageRequestHandler(final IRequestablePage page) {
        return new RenderPageRequestHandler(new PageProvider(page),
                RenderPageRequestHandler.RedirectPolicy.NEVER_REDIRECT);
    }

}