www.gusucode.com > 一个基于extjs的强大聊天插件源码程序 > 一个基于extjs的强大聊天插件/extjame/ext-jame/js/ext2/source/widgets/tree/TreeLoader.js
/*
* Ext JS Library 2.0.2
* Copyright(c) 2006-2008, Ext JS, LLC.
* licensing@extjs.com
*
* http://extjs.com/license
*/
/**
* @class Ext.tree.TreeLoader
* @extends Ext.util.Observable
* A TreeLoader provides for lazy loading of an {@link Ext.tree.TreeNode}'s child
* nodes from a specified URL. The response must be a JavaScript Array definition
* whose elements are node definition objects. eg:
* <pre><code>
[{
id: 1,
text: 'A leaf Node',
leaf: true
},{
id: 2,
text: 'A folder Node',
children: [{
id: 3,
text: 'A child Node',
leaf: true
}]
}]
</code></pre>
* <br><br>
* A server request is sent, and child nodes are loaded only when a node is expanded.
* The loading node's id is passed to the server under the parameter name "node" to
* enable the server to produce the correct child nodes.
* <br><br>
* To pass extra parameters, an event handler may be attached to the "beforeload"
* event, and the parameters specified in the TreeLoader's baseParams property:
* <pre><code>
myTreeLoader.on("beforeload", function(treeLoader, node) {
this.baseParams.category = node.attributes.category;
}, this);
</code></pre><
* This would pass an HTTP parameter called "category" to the server containing
* the value of the Node's "category" attribute.
* @constructor
* Creates a new Treeloader.
* @param {Object} config A config object containing config properties.
*/
Ext.tree.TreeLoader = function(config){
this.baseParams = {};
this.requestMethod = "POST";
Ext.apply(this, config);
this.addEvents(
/**
* @event beforeload
* Fires before a network request is made to retrieve the Json text which specifies a node's children.
* @param {Object} This TreeLoader object.
* @param {Object} node The {@link Ext.tree.TreeNode} object being loaded.
* @param {Object} callback The callback function specified in the {@link #load} call.
*/
"beforeload",
/**
* @event load
* Fires when the node has been successfuly loaded.
* @param {Object} This TreeLoader object.
* @param {Object} node The {@link Ext.tree.TreeNode} object being loaded.
* @param {Object} response The response object containing the data from the server.
*/
"load",
/**
* @event loadexception
* Fires if the network request failed.
* @param {Object} This TreeLoader object.
* @param {Object} node The {@link Ext.tree.TreeNode} object being loaded.
* @param {Object} response The response object containing the data from the server.
*/
"loadexception"
);
Ext.tree.TreeLoader.superclass.constructor.call(this);
};
Ext.extend(Ext.tree.TreeLoader, Ext.util.Observable, {
/**
* @cfg {String} dataUrl The URL from which to request a Json string which
* specifies an array of node definition objects representing the child nodes
* to be loaded.
*/
/**
* @cfg {String} requestMethod The HTTP request method for loading data (defaults to 'POST').
*/
/**
* @cfg {String} url Equivalent to {@link #dataUrl}.
*/
/**
* @cfg {Boolean} preloadChildren If set to true, the loader recursively loads "children" attributes when doing the first load on nodes.
*/
/**
* @cfg {Object} baseParams (optional) An object containing properties which
* specify HTTP parameters to be passed to each request for child nodes.
*/
/**
* @cfg {Object} baseAttrs (optional) An object containing attributes to be added to all nodes
* created by this loader. If the attributes sent by the server have an attribute in this object,
* they take priority.
*/
/**
* @cfg {Object} uiProviders (optional) An object containing properties which
* specify custom {@link Ext.tree.TreeNodeUI} implementations. If the optional
* <i>uiProvider</i> attribute of a returned child node is a string rather
* than a reference to a TreeNodeUI implementation, this that string value
* is used as a property name in the uiProviders object.
*/
uiProviders : {},
/**
* @cfg {Boolean} clearOnLoad (optional) Default to true. Remove previously existing
* child nodes before loading.
*/
clearOnLoad : true,
/**
* Load an {@link Ext.tree.TreeNode} from the URL specified in the constructor.
* This is called automatically when a node is expanded, but may be used to reload
* a node (or append new children if the {@link #clearOnLoad} option is false.)
* @param {Ext.tree.TreeNode} node
* @param {Function} callback
*/
load : function(node, callback){
if(this.clearOnLoad){
while(node.firstChild){
node.removeChild(node.firstChild);
}
}
if(this.doPreload(node)){ // preloaded json children
if(typeof callback == "function"){
callback();
}
}else if(this.dataUrl||this.url){
this.requestData(node, callback);
}
},
doPreload : function(node){
if(node.attributes.children){
if(node.childNodes.length < 1){ // preloaded?
var cs = node.attributes.children;
node.beginUpdate();
for(var i = 0, len = cs.length; i < len; i++){
var cn = node.appendChild(this.createNode(cs[i]));
if(this.preloadChildren){
this.doPreload(cn);
}
}
node.endUpdate();
}
return true;
}else {
return false;
}
},
getParams: function(node){
var buf = [], bp = this.baseParams;
for(var key in bp){
if(typeof bp[key] != "function"){
buf.push(encodeURIComponent(key), "=", encodeURIComponent(bp[key]), "&");
}
}
buf.push("node=", encodeURIComponent(node.id));
return buf.join("");
},
requestData : function(node, callback){
if(this.fireEvent("beforeload", this, node, callback) !== false){
this.transId = Ext.Ajax.request({
method:this.requestMethod,
url: this.dataUrl||this.url,
success: this.handleResponse,
failure: this.handleFailure,
scope: this,
argument: {callback: callback, node: node},
params: this.getParams(node)
});
}else{
// if the load is cancelled, make sure we notify
// the node that we are done
if(typeof callback == "function"){
callback();
}
}
},
isLoading : function(){
return this.transId ? true : false;
},
abort : function(){
if(this.isLoading()){
Ext.Ajax.abort(this.transId);
}
},
/**
* Override this function for custom TreeNode node implementation
*/
createNode : function(attr){
// apply baseAttrs, nice idea Corey!
if(this.baseAttrs){
Ext.applyIf(attr, this.baseAttrs);
}
if(this.applyLoader !== false){
attr.loader = this;
}
if(typeof attr.uiProvider == 'string'){
attr.uiProvider = this.uiProviders[attr.uiProvider] || eval(attr.uiProvider);
}
return(attr.leaf ?
new Ext.tree.TreeNode(attr) :
new Ext.tree.AsyncTreeNode(attr));
},
processResponse : function(response, node, callback){
var json = response.responseText;
try {
var o = eval("("+json+")");
node.beginUpdate();
for(var i = 0, len = o.length; i < len; i++){
var n = this.createNode(o[i]);
if(n){
node.appendChild(n);
}
}
node.endUpdate();
if(typeof callback == "function"){
callback(this, node);
}
}catch(e){
this.handleFailure(response);
}
},
handleResponse : function(response){
this.transId = false;
var a = response.argument;
this.processResponse(response, a.node, a.callback);
this.fireEvent("load", this, a.node, response);
},
handleFailure : function(response){
this.transId = false;
var a = response.argument;
this.fireEvent("loadexception", this, a.node, response);
if(typeof a.callback == "function"){
a.callback(this, a.node);
}
}
});