ajax用途

ajax的所用到的功能

1:级联菜单

例子：在action中

       response.setContentType("text/xml");
        response.setCharacterEncoding("UTF-8");
        PrintWriter out = response.getWriter();
        out.println("<response>");
       
        for(int i=0;i<shiList.size();i++){
            Address address = (Address)shiList.get(i);
                out.println("<city>");
                out.println("<cityname>"+address.getDz()+"</cityname>");
                out.println("<cityvalue>"+address.getDzdm()+"</cityvalue>");
                out.println("</city>");               

           
        }
        out.println("</response>");
        out.flush();
        out.close();

在页面中显示时处理:

 function processor(){
        var result;
        if(XMLHttp.readyState==4){
            if(XMLHttp.status==200){
                result = XMLHttp.responseXML.getElementsByTagName("city");
               
                while(document.form1.shi.options.length>0){
                    document.form1.shi.removeChild(document.form1.shi.childNodes[0]);
                }
               
                var option =document.createElement("OPTION");
                option.text="请选择";
                option.value="";
                document.form1.shi.add(option);
                for(var i=0;i<result.length;i++){
                    var option =document.createElement("OPTION");
                    option.text=result[i].childNodes[0].childNodes[0].nodeValue;
                    option.value=result[i].childNodes[1].childNodes[0].nodeValue;
                    document.form1.shi.add(option);
                }
            }
        }

 

二.用户验证

 失败时在表单旁边加警示例子:

if(xmlHttp.readyState==4){
           var span12=document.getElementById("span1");
           span12.innerHTML="<font color='red'>"+xmlHttp.responseText+"</font>";
         }