Jetty example source code file (ErrorPageErrorHandler.java)

This example Jetty source code file (ErrorPageErrorHandler.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Jetty tags/keywords

dispatcher, errorcoderange, errorcoderange, errorpageerrorhandler, exception, hashmap, http, illegalargumentexception, io, ioexception, map, map, request, response, servlet, servletexception, servletexception, string, string, util

The Jetty ErrorPageErrorHandler.java source code

// ========================================================================
// Copyright 2006 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at 
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ========================================================================

package org.mortbay.jetty.servlet;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.mortbay.jetty.handler.ContextHandler;
import org.mortbay.jetty.handler.ErrorHandler;
import org.mortbay.jetty.webapp.WebAppContext;
import org.mortbay.log.Log;
import org.mortbay.util.TypeUtil;

/** Error Page Error Handler
 * 
 * An ErrorHandler that maps exceptions and status codes to URIs for dispatch using
 * the internal ERROR style of dispatch.
 * @author gregw
 *
 */
public class ErrorPageErrorHandler extends ErrorHandler
{
    protected ServletContext _servletContext;
    protected Map _errorPages; // code or exception to URL
    protected List _errorPageList; // list of ErrorCode by range 

    /* ------------------------------------------------------------ */
    /**
     * @param context
     */
    public ErrorPageErrorHandler()
    {}

    /* ------------------------------------------------------------ */
    /* 
     * @see org.mortbay.jetty.handler.ErrorHandler#handle(java.lang.String, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, int)
     */
    public void handle(String target, HttpServletRequest request, HttpServletResponse response, int dispatch) throws IOException
    {
        if (_errorPages!=null)
        {
            String error_page= null;
            Class exClass= (Class)request.getAttribute(ServletHandler.__J_S_ERROR_EXCEPTION_TYPE);
            
            if (ServletException.class.equals(exClass))
            {
                error_page= (String)_errorPages.get(exClass.getName());
                if (error_page == null)
                {
                    Throwable th= (Throwable)request.getAttribute(ServletHandler.__J_S_ERROR_EXCEPTION);
                    while (th instanceof ServletException)
                        th= ((ServletException)th).getRootCause();
                    if (th != null)
                        exClass= th.getClass();
                }
            }
            
            while (error_page == null && exClass != null )
            {
                error_page= (String)_errorPages.get(exClass.getName());
                exClass= exClass.getSuperclass();
            }
            
            if (error_page == null)
            {
                // look for an exact code match
                Integer code=(Integer)request.getAttribute(ServletHandler.__J_S_ERROR_STATUS_CODE);
                if (code!=null)
                {
                    error_page= (String)_errorPages.get(TypeUtil.toString(code.intValue()));

                    // if still not found
                    if ((error_page == null) && (_errorPageList != null))
                    {
                        // look for an error code range match.
                        for (int i = 0; i < _errorPageList.size(); i++)
                        {
                            ErrorCodeRange errCode = (ErrorCodeRange) _errorPageList.get(i);
                            if (errCode.isInRange(code.intValue()))
                            {
                                error_page = errCode.getUri();
                                break;
                            }
                        }
                    }
                }
            }
            
            if (error_page!=null)
            {
                String old_error_page=(String)request.getAttribute(WebAppContext.ERROR_PAGE);
                if (old_error_page==null || !old_error_page.equals(error_page))
                {
                    request.setAttribute(WebAppContext.ERROR_PAGE, error_page);
                    
                    Dispatcher dispatcher = (Dispatcher) _servletContext.getRequestDispatcher(error_page);
                    try
                    {
                        if(dispatcher!=null)
                        {    
                            dispatcher.error(request, response);
                            return;
                        }
                        else
                        {
                            Log.warn("No error page "+error_page);
                        }
                    }
                    catch (ServletException e)
                    {
                        Log.warn(Log.EXCEPTION, e);
                        return;
                    }
                }
            }
        }
        
        super.handle(target, request, response, dispatch);
    }

    /* ------------------------------------------------------------ */
    /**
     * @return Returns the errorPages.
     */
    public Map getErrorPages()
    {
        return _errorPages;
    }
    
    /* ------------------------------------------------------------ */
    /**
     * @param errorPages The errorPages to set. A map of Exception class name  or error code as a string to URI string
     */
    public void setErrorPages(Map errorPages)
    {
        _errorPages = errorPages;
    }

    /* ------------------------------------------------------------ */
    /** Add Error Page mapping for an exception class
     * This method is called as a result of an exception-type element in a web.xml file
     * or may be called directly
     * @param code The class (or superclass) of the matching exceptions
     * @param uri The URI of the error page.
     */
    public void addErrorPage(Class exception,String uri)
    {
        if (_errorPages==null)
            _errorPages=new HashMap();
        _errorPages.put(exception.getName(),uri);
    }
    
    /* ------------------------------------------------------------ */
    /** Add Error Page mapping for a status code.
     * This method is called as a result of an error-code element in a web.xml file
     * or may be called directly
     * @param code The HTTP status code to match
     * @param uri The URI of the error page.
     */
    public void addErrorPage(int code,String uri)
    {
        if (_errorPages==null)
            _errorPages=new HashMap();
        _errorPages.put(TypeUtil.toString(code),uri);
    }
    
    /* ------------------------------------------------------------ */
    /** Add Error Page mapping for a status code range.
     * This method is not available from web.xml and must be called
     * directly.
     * @param from The lowest matching status code
     * @param to The highest matching status code
     * @param uri The URI of the error page.
     */
    public void addErrorPage(int from, int to, String uri)
    {
        if (_errorPageList == null)
        {
            _errorPageList = new ArrayList();
        }
        _errorPageList.add(new ErrorCodeRange(from, to, uri));
    }

    /* ------------------------------------------------------------ */
    protected void doStart() throws Exception
    {
        super.doStart();
        _servletContext=ContextHandler.getCurrentContext();
    }

    /* ------------------------------------------------------------ */
    protected void doStop() throws Exception
    {
        // TODO Auto-generated method stub
        super.doStop();
    }

    /* ------------------------------------------------------------ */
    /* ------------------------------------------------------------ */
    private class ErrorCodeRange
    {
        private int _from;
        private int _to;
        private String _uri;
        
        ErrorCodeRange(int from, int to, String uri)
            throws IllegalArgumentException
        {
            if (from > to)
                throw new IllegalArgumentException("from>to");
            
            _from = from;
            _to = to;
            _uri = uri;
        }
        
        boolean isInRange(int value)
        {
            if ((value >= _from) && (value <= _to))
            {
                return true;
            }
            
            return false;
        }
        
        String getUri()
        {
            return _uri;
        }
        
        public String toString()
        {
            return "from: " + _from + ",to: " + _to + ",uri: " + _uri;
        }
    }    
}