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$(function(){
$("#uname").onblur(function(){//当xxx失去焦点时
var value = $("#uname").val();//获取id为xxx的元素
$.ajax({
url:"/servlet/AjaxServlet",//要请求服务器URL
data:{"val":value},//这是一个对象,它表示请求参数 服务器端可以使用request。getParamet() 来获取
async:true,//是否为异步请求
cache:false,//是否缓存结果
type:"POST",//请求方式
dataType:"json",//服务器返回的数据是什么类型 json:接收一个对象
success:function(result){//这个函数会在服务器执行成功时被调用,参数result就是服务器返回的值
if(result){
document.getElementById("notice").innerText="已存在";
}else{
document.getElementById("notice").innerText="hh";
}
}
});
});
});
<form action="ZuCe_result.jsp" method="post" name="frm_register">
<table border="0" cellspacing="5" cellpadding="0" width="50%" align="center">
<tr>
<td>用户名:</td>
<td><input type="text" size="30" name="uname" id="uname" /><span id="notice"></span></td>
</tr>
@WebServlet("/AjaxServlet")
public class AjaxServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public AjaxServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
String value = request.getParameter("val");//在adjx的data中进行设置
UserDao dao = new UserDao();
boolean rs = dao.isExitUname("value");
if(rs){
//用jquery的 ajax回调函数 返回的值就是 print中的字符串
response.getWriter().print("true");
}else{
response.getWriter().print("false");
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}