<%...@ page contentType="text/html; charset=UTF-8"%><%...@ page language="java" pageEncoding="UTF-8"%><script language="javascript">...var xmlHttp = false;try ...{ xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");} catch (e) ...{ try ...{ xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e2) ...{ xmlHttp = false; }}if (!xmlHttp && typeof XMLHttpRequest != 'undefined') ...{ xmlHttp = new XMLHttpRequest();}function callServer() ...{ var u_name = document.getElementById("u_name").value; if ((u_name == null) || (u_name == "")) w; var url = "do.jsp"; var aa="name="+u_name; //alert (aa); xmlHttp.open("POST", url, false); xmlHttp.setrequestheader("content-length",aa.length); //使用POST方式需要加 xmlHttp.setrequestheader("content-type","application/x-www-form-urlencoded"); //使用POST方式需要加 xmlHttp.onreadystatechange = updatePage; xmlHttp.send(aa); //发送提交参数}function updatePage() ...{ if (xmlHttp.readyState < 4) ...{ test1.innerHTML="正在检测"; } if (xmlHttp.readyState == 4) ...{ var response = xmlHttp.responseText; test1.innerHTML=response; //接收do.jsp参数 } if (test1.innerHTML=="已被注册")...{ document.form1.submit.disabled=true } if (test1.innerHTML=="可以注册")...{ document.form1.submit.disabled=false } }</script><form name="form1" action="t1.jsp" method="post" autocomplete="off">用户名: <input type="text" name="u_name" id="u_name" onChange="callServer();" /> <span id="test1">是否能注册</span><br>密 码:<input type="password" /> <input type="submit" name="submit" value="注册" /></form> <%@ page contentType="text/html; charset=UTF-8"%><%@ page language="java" pageEncoding="UTF-8"%><%@page import="test.AjaxTest"%><%String cname=request.getParameter("name");//out.print(cname);AjaxTest at = new AjaxTest();if(at.getName(cname))...{ out.print("可以注册");}else...{ out.print("已被注册"); out.print("sssssssssssssssssssssssss");}%>