Jetty example source code file (ajax.js)

This example Jetty source code file (ajax.js) 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

activexobject, array, cdata, error, error, evutil, evutil, ie, ie, non-ie, xmlhttprequest, xmlhttprequest, xmlserializer

The Jetty ajax.js source code

// AJAX  handler
var ajax = 
{
  poll: true,
  _first: true,
  _pollEvent: function(first) {},
  _handlers: new Array(),
  
  _messages:0,
  _messageQueue: '',
  _queueMessages: false,
  
  
  _xhr: function(method,uri,body,handler)
  {
  	var req=null;
  	
    if (window.XMLHttpRequest) { // Non-IE browsers
      	req = new XMLHttpRequest();
	}
	else if (window.ActiveXObject) { // IE
      	req = new ActiveXObject("Microsoft.XMLHTTP");
	}
	
    req.onreadystatechange=function()
    {
    	if (req.readyState==4) 
    	{
    		try
    		{
    	    	handler(req);
    		}
    		catch(e)
    		{
    		    window.status="ERROR: xhr "+e.name + ": " + e.message;
    			// alert(e.name+" "+e.message);
    		}
    	}
    }
	
    if (body!=null)
    {
       req.open(method,uri,true);
       req.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
	   req.send(body);
    }
    else
    {
	   req.open(method,uri,true);
       req.send(null);
    }
  },
  
  _messageHandler: function(request) 
  {
    var qm=ajax._queueMessages;
    ajax._queueMessages=true;
    try
    {
      if (request.status == 200)
      {
        var response = request.responseXML.getElementsByTagName("ajax-response");
        if (response != null && response.length == 1)
        {
          var responses = response[0].getElementsByTagName("response");
	  
          for ( var i = 0 ; i < responses.length ; i++ ) 
          {
            var responseElement = responses[i];
	    
            // only process nodes of type element.....
            if ( responseElement.nodeType != 1 )
              continue;

            var id   = responseElement.getAttribute('id');
            
            var handler = ajax._handlers[id];
	    
	    if (handler!=null)
            {
              for (var j = 0; j < responseElement.childNodes.length; j++) 
              {
                var child = responseElement.childNodes[j]
                if (child.nodeType == 1) 
                {
                  handler(child);
                }
              }
            }
          }
        }
      }
    }
    catch(e)
    {
    	window.status="ERROR: _messageHandler "+e.name + ": " + e.message;
      // alert(e.name + ": " + e.message);
    }
    ajax._queueMessages=qm;
    
    if (!ajax._queueMessages && ajax._messages>0)
    {
      var body = ajax._messageQueue;
      ajax._messageQueue='';
      ajax._messages=0;
      
      ajax._xhr('POST','.',body,ajax._pollHandler);
      
    }
  },
  
  _pollHandler: function(request) 
  {
    if (request.status != 200)
      return;
      
    ajax._queueMessages=true;
    try
    {
      ajax._messageHandler(request);
      ajax._pollEvent(ajax._first);
      ajax._first=false;
    }
    catch(e)
    {
    	window.status="ERROR: pollHandler "+e.name + ": " + e.message;
      // alert(e.name + ": " + e.message);
    }
    
    ajax._queueMessages=false;
    
    if (ajax._messages==0)
    {
      if (ajax.poll)
        ajax._xhr('POST','.?ajax=poll&message=poll',null,ajax._pollHandler);
    }
    else
    {
      var body = ajax._messageQueue+'&ajax=poll&message=poll';
      ajax._messageQueue='';
      ajax._messages=0;
      ajax._xhr('POST','.',body,ajax._pollHandler);
    }
  },
  
  addPollHandler : function(func)
  {
    var old = ajax._pollEvent;
    ajax._pollEvent = function(first) 
    {
      old(first);
      func(first);
    }
  },
  
  // Listen on a channel or topic.   handler must be a function taking a message arguement
  addListener : function(id,handler)
  {   
    ajax._handlers[id]=handler;
  },
  
  // remove Listener from channel or topic.  
  removeListener : function(id)
  {   
    ajax._handlers[id]=null;
  },
  
  sendMessage : function(destination,message)
  {
    message=message.replace('%','%25');
    message=message.replace('&','%26');
    message=message.replace('=','%3D');
    if (ajax._queueMessages)
    {
      ajax._messageQueue+=(ajax._messages==0?'ajax=':'&ajax=')+destination+'&message='+message;
      ajax._messages++;
    }
    else
    {
      ajax._xhr('POST','.','ajax='+destination+'&message='+message,ajax._messageHandler);
    }
  },
  
  _startPolling : function()
  {
    if (ajax.poll)
      ajax._xhr('POST','.?ajax=poll&message=poll&timeout=0',null,ajax._pollHandler);
  },
  
  getContentAsString: function( parentNode ) {
      return parentNode.xml != undefined ?
         ajax._getContentAsStringIE(parentNode) :
         ajax._getContentAsStringMozilla(parentNode);
  },

  _getContentAsStringIE: function(parentNode) {
     var contentStr = "";
     for ( var i = 0 ; i < parentNode.childNodes.length ; i++ ) {
         var n = parentNode.childNodes[i];
         if (n.nodeType == 4) {
             contentStr += n.nodeValue;
         }
         else {
           contentStr += n.xml;
       }
     }
     return contentStr;
  },

  _getContentAsStringMozilla: function(parentNode) {
     var xmlSerializer = new XMLSerializer();
     var contentStr = "";
     for ( var i = 0 ; i < parentNode.childNodes.length ; i++ ) {
          var n = parentNode.childNodes[i];
          if (n.nodeType == 4) { // CDATA node
              contentStr += n.nodeValue;
          }
          else {
            contentStr += xmlSerializer.serializeToString(n);
        }
     }
     return contentStr;
  }
  
};

var EvUtil =
{
    getKeyCode : function(ev)
    {
        var keyc;
        if (window.event)
            keyc=window.event.keyCode;
        else
            keyc=ev.keyCode;
        return keyc;
    }
};

Behaviour.addLoadEvent(ajax._startPolling);