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Jetty example source code file (AjaxFilter.java)

This example Jetty source code file (AjaxFilter.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

ajaxresponse, ajaxresponse, filterchain, http, httpservletrequest, httpservletrequest, httpservletresponse, io, ioexception, printwriter, printwriter, request, response, servlet, servletcontext, servletexception, string, string, stringwriter

The Jetty AjaxFilter.java source code

//========================================================================
//$Id: AjaxFilter.java,v 1.1 2005/11/14 17:45:56 gregwilkins Exp $
//Copyright 2004-2005 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.util.ajax;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class AjaxFilter implements Filter
{
    ServletContext context;

    public void init(FilterConfig filterConfig) throws ServletException
    {
        context=filterConfig.getServletContext();
    }

    /* ------------------------------------------------------------ */
    /**
     * @return Returns the context.
     */
    public ServletContext getContext()
    {
        return context;
    }

    /* ------------------------------------------------------------ */
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException
    {
        String[] method=request.getParameterValues("ajax");
        String[] message=request.getParameterValues("message");
        
        if (method!=null && method.length>0)
        {
            HttpServletRequest srequest = (HttpServletRequest)request;
            HttpServletResponse sresponse = (HttpServletResponse) response;
            
            StringWriter sout = new StringWriter();
            PrintWriter out = new PrintWriter(sout);
            
            out.println("<ajax-response>");
            AjaxResponse aResponse =new AjaxResponse(srequest,out);
            
            for (int i=0;i<method.length;i++)
            {
                handle(method[i],message[i],srequest,aResponse);
            }

            out.println("</ajax-response>");
            byte[] ajax = sout.toString().getBytes("UTF-8");
            sresponse.setHeader( "Pragma", "no-cache" );
            sresponse.addHeader( "Cache-Control", "must-revalidate,no-cache,no-store" );
            sresponse.setDateHeader("Expires", 0);
            sresponse.setContentType("text/xml; charset=UTF-8");
            sresponse.setContentLength(ajax.length);
            sresponse.getOutputStream().write(ajax);
            sresponse.flushBuffer();
        }
        else
            chain.doFilter(request, response);
    }

    public void handle(String method, String message, HttpServletRequest request,AjaxResponse response)
    {    
        response.elementResponse(null, "<span class=\"error\">No implementation for "+method+" "+request.getParameter("member")+"");
    }
    
    public void destroy()
    {
        context=null;
    }

    public static String encodeText(String s)
    {
        StringBuffer buf=null;
        for (int i=0;i<s.length();i++)
        {
            char c=s.charAt(i);
            String r=null;
            switch(c)
            {
                case '<': r="<"; break;
                case '>': r=">"; break;
                case '&': r="&"; break;
            }
            
            if (r!=null)
            {
                if (buf==null)
                {
                    buf=new StringBuffer(s.length()*2);
                    buf.append(s.subSequence(0,i));
                }
                buf.append(r);
            }
            else if (buf!=null)
                buf.append(c);
        }
        
        if (buf!=null)
            return buf.toString();
        return s;
    }
    
    public static class AjaxResponse
    {
        private HttpServletRequest request;
        private PrintWriter out;
        private AjaxResponse(HttpServletRequest request,PrintWriter out)
        {this.out=out; this.request=request;}
        
        public void elementResponse(String id,String element)
        {
            if (id==null)
                id = request.getParameter("id");
            if (id==null)
                id="unknown";
            out.println("<response type=\"element\" id=\""+id+"\">"+element+"");
        }
        
        public void objectResponse(String id,String element)
        {
            if (id==null)
                id = request.getParameter("id");
            if (id==null)
                id="unknown";
            
            out.println("<response type=\"object\" id=\""+id+"\">"+element+"");
        }
    }
}

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