在数据库中创建表
加载org.json.jar文件
创建输入表单
创建服务器端页面以使用姓名搜索员工 
 
index.html
 <!DOCTYPE html>
 <html>
 <head>
 <title>Email Finder Example</title>
 <script>
 var request;
 function sendInfo(){
 var email=document.vinform.email.value;
 var url="emailfinder.jsp?email="+email;
 if(window.XMLHttpRequest){
 request=new XMLHttpRequest();
 }
 else if(window.ActiveXObject){
 request=new ActiveXObject("Microsoft.XMLHTTP");
 }
 try{
 request.onreadystatechange=getInfo;
 request.open("GET",url,true);
 request.send();
 }catch(e){alert("Unable to connect to server");}
 }
 function getInfo(){
 if(request.readyState==4){
 var val=request.responseText;
 document.getElementById('mylocation').innerHTML=val;
 }
 }
 </script>
 </head>
 <body>
 <marquee><h1>AJAX Email Checker Example</h1></marquee>
 <form name="vinform">
 <input type="email" name="email" placeholder="enter email"/>
 <input type="button" onclick="sendInfo()" value="Check Availability"/>
 <span id="mylocation"></span>
 </form>
 </body></html>
 
emailfinder.jsp
 <%@ page import="java.sql.*" %>
 <%
 String email=request.getParameter("email");
 if(email.contains("@")&&email.contains(".")){
 try{
 Class.forName("oracle.jdbc.driver.OracleDriver");
 Connection con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","system","oracle");
 PreparedStatement ps=con.prepareStatement("select * from user100 where email=?");
 ps.setString(1,email);
 ResultSet rs=ps.executeQuery();
 if(rs.next()){
 out.print("Unavailable! <img src='unchecked.gif'/>");
 }else{
 out.print("Available! <img src='checked.gif'/>");
 }
 }catch(Exception e){out.print(e);}
 }else{
 out.print("Invalid email!");
 }
 %>
 

