动态加载ＤＷＲ

Util.loadDwr = function(dwrName, onLoad, onError) {
	var url = 'dwr/interface/';
	var scriptTag = document.getElementById(dwrName);
	var oHead = document.getElementsByTagName('HEAD').item(0); 
	if (!scriptTag) {
		var script = document.createElement('script'), me = this, onLoadFn = function() {
			me.cleanupScriptElement(script);
			onLoad();
		}, onErrorFn = function() {
			me.cleanupScriptElement(script);
			onError();
		};
		script.id = dwrName;
		script.type = 'text/javascript';
		script.src = url + dwrName + ".js";
		script.onload = onLoadFn;
		script.onerror = onErrorFn;
		script.onreadystatechange = function() {
			if (this.readyState === 'loaded' || this.readyState === 'complete') {
				onLoadFn();
			}
		};
		oHead.appendChild(script);
		return script;
	} else {
		onLoad();
	}
}