ajax 原生态和jquery封装区别

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);  
           }   
    });