Ajax技术

1按钮 2010-11-7 author：heguikun

<input type="text" name="petInfo.petName" value="晴天大圣" οnblur="return checkPetExists(this)">

2.脚本

<script type="text/javascript"> //宠物名验证并使用Ajax技术 var xmlHttpRequest;//必须要设置全局变量,否则报对象未定义 function createXmlHttpRequest() {  if(window.ActiveXObject)  {//IE浏览器    xmlHttpRequest=new ActiveXObject("Microsoft.XMLHTTP");  }  else{//非IE浏览器     xmlHttpRequest=new XMLHttpRequest();  }  return xmlHttpRequest; } function checkPetExists(oCtl) {  var petName=oCtl.value;  if(!petName)  {  alert("宠物名不能为空！");  oCtl.focus();  return;  }  //请求字符串  var url="pet.do?operate=doCheckUserExists&petName="+petName;  //1.创建XMLHttpRequest组建  var xmlHttpRequest=createXmlHttpRequest();  //2.设置回调函数  xmlHttpRequest.onreadystatechange=petaAjax;  //3.初始化xmlHttpRequest组件  xmlHttpRequest.open("GET",url,true);  //发送请求  xmlHttpRequest.send(null); } function  petaAjax() {   if(xmlHttpRequest.readyState==4&&xmlHttpRequest.status==200)    {     var b=xmlHttpRequest.responseText;//获取打印的只       if(b=="true")        {          alert("该宠物名已被使用");        }else        {          alert("该宠物名可用！");        }     } }

</script>

3.Action

 //ajax技术 public ActionForward doCheckUserExists(ActionMapping mapping,   ActionForm form, HttpServletRequest request,   HttpServletResponse response) throws IOException {  String petName = request.getParameter("petName");

  petName= new String(petName.getBytes("iso-8859-1"), "gbk");//iso-8859-1  System.out.println(petName);  List list=allBiz.query("from  PetInfo where petName='"+petName+"'");  PrintWriter out=response.getWriter();  if (list!=null&&list.size()>0) {   out.write("true");//打印出来时为了回调函数获取这个字符串  }else  {  out.write("false");  }  return null; }