ajax 原生态和jquery封装区别

一、原生态

var xmlHttp = false;
try{
	if( xmlHttp && xmlHttp.readyState != 0 ){
	    xmlHttp.abort();
         }
	if (!xmlHttp){
	    xmlHttp = getXMLHTTPObj();
	}
	if(xmlHttp){
	    var url = "pages/overlapanalysis_PostResult.jsp?dkName="+dkName+"&annlysisBusinessType="+annlysisBusinessType
				           +"&coordString="+coordString+"&mapID="+mapID+"&phyLayerID="+phyLayerID+"&phyLayerName="+phyLayerName
						   +"&fldNames="+fldNames+"&whereSql="+whereSql;
	    xmlHttp.open("POST",encodeURI(encodeURI(url)) , true);
	    xmlHttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	    xmlHttp.setRequestHeader("Content-Type","text/xml;charset=GBK");
	   //设置回调函数
	   xmlHttp.onreadystatechange = function () {
	      try{
		if (xmlHttp.readyState == 1){
		    window.status = "叠加分析中......";
		}else if (xmlHttp.readyState == 2){
		    window.status = "叠加分析完毕";
		}else if (xmlHttp.readyState == 3){
		    window.status = "叠加分析完毕.";
		}else if (xmlHttp.readyState == 4){
		    window.status = "叠加分析完毕.";
		    var retStr = xmlHttp.responseText;
		    document.getElementById("data_txt").value = retStr;
		}
		}catch (e){
		    alert("数据加载失败!:" + e);
		}
	}
	xmlHttp.send(null);
	}else{
	    alert("XMLHTTP对象创建失败");
	 }
	}catch (e){
	    alert("数据加载失败!:" + e);
}

 //创建XMLHTTP对象
function getXMLHTTPObj(){
		  var obj = null;
		  try{
			  obj = new ActiveXObject("Msxml2.XMLHTTP");
		  }catch(e){
		try{
			obj = new ActiveXObject("Microsoft.XMLHTTP");
		}catch(sc){
			obj = null;
			alert('创建XMLHTTP对象失败！');
		}
	  }
	 if( !obj && typeof XMLHttpRequest != "undefined" ){  //not Microsoft Integer Explorer
		 obj = new XMLHttpRequest();
	 }
	 return obj;
}

$.ajax({
           url:"pages/overlapanalysis_PostResult.jsp",
           type:"post",
           data:"dkName="+dkName+"&annlysisBusinessType="+annlysisBusinessType
				           +"&coordString="+coordStr+"&mapID="+mapID+"&phyLayerID="+phyLayerID+"&phyLayerName="+phyLayerName
						   +"&fldNames="+fldNames+"&whereSql="+whereSql,
           async : true, //默认为true 异步
		   dataType:"html",
           error:function(){
               alert("叠加分析失败");
           },
           success:function(data){
               setAttributeValuestt(layerType,coordStr,data);
           }
    });

当使用的参数较多且有的参数过长时建议使用jquery的，使用原生态的可以会截掉部分传递的参数（如coordStr是很多坐标串可能就会失败）。