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/data/ScriptTagProxy.js
/*
* Ext JS Library 2.0.2
* Copyright(c) 2006-2008, Ext JS, LLC.
* licensing@extjs.com
*
* http://extjs.com/license
*/
/**
* @class Ext.data.ScriptTagProxy
* @extends Ext.data.DataProxy
* An implementation of Ext.data.DataProxy that reads a data object from a URL which may be in a domain
* other than the originating domain of the running page.<br>
* <p>
* <b>Note that if you are retrieving data from a page that is in a domain that is NOT the same as the originating domain
* of the running page, you must use this class, rather than HttpProxy.</b><br>
* <p>
* The content passed back from a server resource requested by a ScriptTagProxy is executable JavaScript
* source code that is used as the source inside a <script> tag.<br>
* <p>
* In order for the browser to process the returned data, the server must wrap the data object
* with a call to a callback function, the name of which is passed as a parameter by the ScriptTagProxy.
* Below is a Java example for a servlet which returns data for either a ScriptTagProxy, or an HttpProxy
* depending on whether the callback name was passed:
* <p>
* <pre><code>
boolean scriptTag = false;
String cb = request.getParameter("callback");
if (cb != null) {
scriptTag = true;
response.setContentType("text/javascript");
} else {
response.setContentType("application/x-json");
}
Writer out = response.getWriter();
if (scriptTag) {
out.write(cb + "(");
}
out.print(dataBlock.toJsonString());
if (scriptTag) {
out.write(");");
}
</code></pre>
*
* @constructor
* @param {Object} config A configuration object.
*/
Ext.data.ScriptTagProxy = function(config){
Ext.data.ScriptTagProxy.superclass.constructor.call(this);
Ext.apply(this, config);
this.head = document.getElementsByTagName("head")[0];
};
Ext.data.ScriptTagProxy.TRANS_ID = 1000;
Ext.extend(Ext.data.ScriptTagProxy, Ext.data.DataProxy, {
/**
* @cfg {String} url The URL from which to request the data object.
*/
/**
* @cfg {Number} timeout (Optional) The number of milliseconds to wait for a response. Defaults to 30 seconds.
*/
timeout : 30000,
/**
* @cfg {String} callbackParam (Optional) The name of the parameter to pass to the server which tells
* the server the name of the callback function set up by the load call to process the returned data object.
* Defaults to "callback".<p>The server-side processing must read this parameter value, and generate
* javascript output which calls this named function passing the data object as its only parameter.
*/
callbackParam : "callback",
/**
* @cfg {Boolean} nocache (Optional) Defaults to true. Disable cacheing by adding a unique parameter
* name to the request.
*/
nocache : true,
/**
* Load data from the configured URL, read the data object into
* a block of Ext.data.Records using the passed Ext.data.DataReader implementation, and
* process that block using the passed callback.
* @param {Object} params An object containing properties which are to be used as HTTP parameters
* for the request to the remote server.
* @param {Ext.data.DataReader} reader The Reader object which converts the data
* object into a block of Ext.data.Records.
* @param {Function} callback The function into which to pass the block of Ext.data.Records.
* The function must be passed <ul>
* <li>The Record block object</li>
* <li>The "arg" argument from the load function</li>
* <li>A boolean success indicator</li>
* </ul>
* @param {Object} scope The scope in which to call the callback
* @param {Object} arg An optional argument which is passed to the callback as its second parameter.
*/
load : function(params, reader, callback, scope, arg){
if(this.fireEvent("beforeload", this, params) !== false){
var p = Ext.urlEncode(Ext.apply(params, this.extraParams));
var url = this.url;
url += (url.indexOf("?") != -1 ? "&" : "?") + p;
if(this.nocache){
url += "&_dc=" + (new Date().getTime());
}
var transId = ++Ext.data.ScriptTagProxy.TRANS_ID;
var trans = {
id : transId,
cb : "stcCallback"+transId,
scriptId : "stcScript"+transId,
params : params,
arg : arg,
url : url,
callback : callback,
scope : scope,
reader : reader
};
var conn = this;
window[trans.cb] = function(o){
conn.handleResponse(o, trans);
};
url += String.format("&{0}={1}", this.callbackParam, trans.cb);
if(this.autoAbort !== false){
this.abort();
}
trans.timeoutId = this.handleFailure.defer(this.timeout, this, [trans]);
var script = document.createElement("script");
script.setAttribute("src", url);
script.setAttribute("type", "text/javascript");
script.setAttribute("id", trans.scriptId);
this.head.appendChild(script);
this.trans = trans;
}else{
callback.call(scope||this, null, arg, false);
}
},
// private
isLoading : function(){
return this.trans ? true : false;
},
/**
* Abort the current server request.
*/
abort : function(){
if(this.isLoading()){
this.destroyTrans(this.trans);
}
},
// private
destroyTrans : function(trans, isLoaded){
this.head.removeChild(document.getElementById(trans.scriptId));
clearTimeout(trans.timeoutId);
if(isLoaded){
window[trans.cb] = undefined;
try{
delete window[trans.cb];
}catch(e){}
}else{
// if hasn't been loaded, wait for load to remove it to prevent script error
window[trans.cb] = function(){
window[trans.cb] = undefined;
try{
delete window[trans.cb];
}catch(e){}
};
}
},
// private
handleResponse : function(o, trans){
this.trans = false;
this.destroyTrans(trans, true);
var result;
try {
result = trans.reader.readRecords(o);
}catch(e){
this.fireEvent("loadexception", this, o, trans.arg, e);
trans.callback.call(trans.scope||window, null, trans.arg, false);
return;
}
this.fireEvent("load", this, o, trans.arg);
trans.callback.call(trans.scope||window, result, trans.arg, true);
},
// private
handleFailure : function(trans){
this.trans = false;
this.destroyTrans(trans, false);
this.fireEvent("loadexception", this, null, trans.arg);
trans.callback.call(trans.scope||window, null, trans.arg, false);
}
});