//异步ajax调用
/**
 * 异步调用ajax，成功后返回值，作为回调函数的参数 调用失败会提示
 * 
 * @param {}
 *            urlStr
 * @param {}
 *            paramsObj
 * @param {}
 *            callbackFunc
 */
function ajaxCall(urlStr, paramsObj, callbackFunc) {
	Ext.Ajax.request({
				url : urlStr,
				params : paramsObj,
				method : 'POST',
				success : function(response) {
					if (callbackFunc) {
						var result = Ext.util.JSON
								.decode(response.responseText);
						var cbfn = callbackFunc.createCallback(result);
						cbfn();
					}
				},
				failure : function() {
					Ext.Msg.alert("提示", "方法调用失败");
				}
			});
}

/**
 *通用JS 同步ajax调用 返回json Object
 * 
 * @param {}
 *            urlStr
 * @param {}
 *            paramsStr 为字符串键值对形式“key=value&key2=value2”
 * @return {} 返回json Object
 */
function ajaxSyncCall(urlStr, paramsStr) {
	var obj;
	var value;
	if (window.ActiveXObject) {
		obj = new ActiveXObject('Microsoft.XMLHTTP');
	} else if (window.XMLHttpRequest) {
		obj = new XMLHttpRequest();
	}
	obj.open('POST', urlStr, false);
	obj.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
	obj.send(paramsStr);
	var result = Ext.util.JSON.decode(obj.responseText);
	return result;
}

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//EXTJS 同步ajax调用
var conn = Ext.lib.Ajax.getConnectionObject().conn;
conn.open("GET", 'your url',false);
conn.send(null);
alert(conn.responseText);

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EXTJS 修改Ext.Ajax.request真正的请求方法Ext.lib.Ajax.request ，通过sync:true实现同步调用ajax

Ext.lib.Ajax.request = function(method, uri, cb, data, options) {     
    if(options){     
        var hs = options.headers;     
        if(hs){     
            for(var h in hs){     
                if(hs.hasOwnProperty(h)){     
                    this.initHeader(h, hs[h], false);     
                }     
            }     
        }     
        if(options.xmlData){     
            if (!hs || !hs['Content-Type']){     
                this.initHeader('Content-Type', 'text/xml', false);     
            }     
            method = (method ? method : (options.method ? options.method : 'POST'));     
            data = options.xmlData;     
        }else if(options.jsonData){     
            if (!hs || !hs['Content-Type']){     
                this.initHeader('Content-Type', 'application/json', false);     
            }     
            method = (method ? method : (options.method ? options.method : 'POST'));     
            data = typeof options.jsonData == 'object' ? Ext.encode(options.jsonData) : options.jsonData;     
        }     
    }    

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?return this["sync" in options ? "syncRequest" : "asyncRequest"](method, uri, cb, data);//这句制定调用的方法，如果sync传递了就调用syncRequest， 否则调用原来的方法asyncRequest};

Ext.lib.Ajax.syncRequest = function(method, uri, callback, postData)     
{     
    var o = this.getConnectionObject();     
   
    if (!o) {     
        return null;     
    }     
    else {     
        o.conn.open(method, uri, false);     
   
        if (this.useDefaultXhrHeader) {     
            if (!this.defaultHeaders['X-Requested-With']) {     
                this.initHeader('X-Requested-With', this.defaultXhrHeader, true);     
            }     
        }     
   
        if(postData && this.useDefaultHeader && (!this.hasHeaders || !this.headers['Content-Type'])){     
            this.initHeader('Content-Type', this.defaultPostHeader);     
        }     
   
        if (this.hasDefaultHeaders || this.hasHeaders) {     
            this.setHeader(o);     
        }     
   
        o.conn.send(postData || null);     
        this.handleTransactionResponse(o, callback);     
        return o;     
    }     
};    

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