opmlstore.js

这是一个ajax的例子大家好好的看看就是一个鱼眼的效果

				something.tagName == 'outline' &&
				something.ownerDocument === this._xmlData); //Boolean
	},
	
	isItemLoaded: function(/* anything */ something){
		//	summary: 
		//		See dojo.data.api.Read.isItemLoaded()
		// 		OpmlStore loads every item, so if it's an item, then it's loaded.
		return this.isItem(something); //Boolean
	},
	
	loadItem: function(/* item */ item){
		//	summary: 
		//		See dojo.data.api.Read.loadItem()
		//	description:
		//		The OpmlStore always loads all items, so if it's an item, then it's loaded.
		//		From the dojo.data.api.Read.loadItem docs:
		//			If a call to isItemLoaded() returns true before loadItem() is even called,
		//			then loadItem() need not do any work at all and will not even invoke the callback handlers.
	},

	getLabel: function(/* item */ item){
		//	summary: 
		//		See dojo.data.api.Read.getLabel()
		if(this.isItem(item)){
			return this.getValue(item,this.label); //String
		}
		return undefined; //undefined
	},

	getLabelAttributes: function(/* item */ item){
		//	summary: 
		//		See dojo.data.api.Read.getLabelAttributes()
		return [this.label]; //array
	},

	// The dojo.data.api.Read.fetch() function is implemented as
	// a mixin from dojo.data.util.simpleFetch.
	// That mixin requires us to define _fetchItems().
	_fetchItems: function(	/* Object */ keywordArgs, 
							/* Function */ findCallback, 
							/* Function */ errorCallback){
		//	summary: 
		//		See dojo.data.util.simpleFetch.fetch()
		
		var self = this;
		var filter = function(requestArgs, arrayOfItems){
			var items = null;
			if(requestArgs.query){
				items = [];
				var ignoreCase = requestArgs.queryOptions ? requestArgs.queryOptions.ignoreCase : false; 

				//See if there are any string values that can be regexp parsed first to avoid multiple regexp gens on the
				//same value for each item examined.  Much more efficient.
				var regexpList = {};
				for(var key in requestArgs.query){
					var value = requestArgs.query[key];
					if(typeof value === "string"){
						regexpList[key] = dojo.data.util.filter.patternToRegExp(value, ignoreCase);
					}
				}

				for(var i = 0; i < arrayOfItems.length; ++i){
					var match = true;
					var candidateItem = arrayOfItems[i];
					for(var key in requestArgs.query){
						var value = requestArgs.query[key];
						if(!self._containsValue(candidateItem, key, value, regexpList[key])){
							match = false;
						}
					}
					if(match){
						items.push(candidateItem);
					}
				}
			}else{
				// We want a copy to pass back in case the parent wishes to sort the array.  We shouldn't allow resort 
				// of the internal list so that multiple callers can get lists and sort without affecting each other.
				if(arrayOfItems.length> 0){
					items = arrayOfItems.slice(0,arrayOfItems.length); 
				}
			}
			findCallback(items, requestArgs);
		};

		if(this._loadFinished){
			filter(keywordArgs, this._getItemsArray(keywordArgs.queryOptions));
		}else{

			//If fetches come in before the loading has finished, but while
			//a load is in progress, we have to defer the fetching to be 
			//invoked in the callback.
			if(this._loadInProgress){
				this._queuedFetches.push({args: keywordArgs, filter: filter});
			}else{
				if(this.url !== ""){
					this._loadInProgress = true;
					var getArgs = {
							url: self.url, 
							handleAs: "xml"
						};
					var getHandler = dojo.xhrGet(getArgs);
					getHandler.addCallback(function(data){
						self._processRawXmlTree(data);
						filter(keywordArgs, self._getItemsArray(keywordArgs.queryOptions));
						self._handleQueuedFetches();
					});
					getHandler.addErrback(function(error){
						throw error;
					});
				}else if(this._opmlData){
					this._processRawXmlTree(this._opmlData);
					this._opmlData = null;
					filter(keywordArgs, this._getItemsArray(keywordArgs.queryOptions));
				}else{
					throw new Error("dojox.data.OpmlStore: No OPML source data was provided as either URL or XML data input.");
				}
			}
		}
	},
	
	getFeatures: function(){
		// summary: See dojo.data.api.Read.getFeatures()
		var features = {
			'dojo.data.api.Read': true,
			'dojo.data.api.Identity': true
		};
		return features; //Object
	},

/***************************************
     dojo.data.api.Identity API
***************************************/
	getIdentity: function(/* item */ item){
		//	summary: 
		//		See dojo.data.api.Identity.getIdentity()
		if(this.isItem(item)){
			//No ther way to do this other than O(n) without
			//complete rework of how the tree stores nodes.
			for(var i in this._identityMap){
				if(this._identityMap[i] === item){
					return i;
				}
			}
		}
		return null; //null
	},

	fetchItemByIdentity: function(/* Object */ keywordArgs){
		//	summary: 
		//		See dojo.data.api.Identity.fetchItemByIdentity()

		//Hasn't loaded yet, we have to trigger the load.
		if(!this._loadFinished){
			var self = this;
			if(this.url !== ""){
				//If fetches come in before the loading has finished, but while
				//a load is in progress, we have to defer the fetching to be 
				//invoked in the callback.
				if(this._loadInProgress){
					this._queuedFetches.push({args: keywordArgs});
				}else{
					this._loadInProgress = true;
					var getArgs = {
							url: self.url, 
							handleAs: "xml"
						};
					var getHandler = dojo.xhrGet(getArgs);
					getHandler.addCallback(function(data){
						var scope =  keywordArgs.scope?keywordArgs.scope:dojo.global;
						try{
							self._processRawXmlTree(data);
							var item = self._identityMap[keywordArgs.identity];
							if(!self.isItem(item)){
								item = null;
							}
							if(keywordArgs.onItem){
								keywordArgs.onItem.call(scope, item);
							}
							self._handleQueuedFetches();
						}catch(error){
							if(keywordArgs.onError){
								keywordArgs.onError.call(scope, error);
							}
						}
					});
					getHandler.addErrback(function(error){
						this._loadInProgress = false;
						if(keywordArgs.onError){
							var scope =  keywordArgs.scope?keywordArgs.scope:dojo.global;
							keywordArgs.onError.call(scope, error);
						}
					});
				}
			}else if(this._opmlData){
				this._processRawXmlTree(this._opmlData);
				this._opmlData = null;
				var item = this._identityMap[keywordArgs.identity];
				if(!self.isItem(item)){
					item = null;
				}
				if(keywordArgs.onItem){
					var scope =  keywordArgs.scope?keywordArgs.scope:dojo.global;
					keywordArgs.onItem.call(scope, item);
				}
			}
		}else{
			//Already loaded.  We can just look it up and call back.
			var item = this._identityMap[keywordArgs.identity];
			if(!this.isItem(item)){
				item = null;
			}
			if(keywordArgs.onItem){
				var scope =  keywordArgs.scope?keywordArgs.scope:dojo.global;
				keywordArgs.onItem.call(scope, item);
			}
		}
	},

	getIdentityAttributes: function(/* item */ item){
		 //	summary: 
		 //		See dojo.data.api.Identity.getIdentifierAttributes()
		 
		 //Identity isn't a public attribute in the item, it's the node count.
		 //So, return null.
		 return null;
	},

	_handleQueuedFetches: function(){
		//	summary: 
		//		Internal function to execute delayed request in the store.
		//Execute any deferred fetches now.
		if (this._queuedFetches.length > 0) {
			for(var i = 0; i < this._queuedFetches.length; i++){
				var fData = this._queuedFetches[i];
				var delayedQuery = fData.args;
				var delayedFilter = fData.filter;
				if(delayedFilter){
					delayedFilter(delayedQuery, this._getItemsArray(delayedQuery.queryOptions)); 
				}else{
					this.fetchItemByIdentity(delayedQuery);
				}
			}
			this._queuedFetches = [];
		}
	},

	close: function(/*dojo.data.api.Request || keywordArgs || null */ request){
		 //	summary: 
		 //		See dojo.data.api.Read.close()
	}
});
//Mix in the simple fetch implementation to this class.
dojo.extend(dojox.data.OpmlStore,dojo.data.util.simpleFetch);
	

}