1：注册表单<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>get方式请求数据，不要传参数</title>
</head>
<body>
<input type="text" name="username" id="username" onblur="textAjax()">
<span id="mydiv" ></span>
<input type="password" name="password">
<input type="button" value="测试是否可以注册" onclick="textAjax()">
<script type="text/javascript">
function textAjax()
{
//获取xmlHttpRequest对象(ajax引擎)
var xmlhttprequest;
if (window.XMLHttpRequest) {
xmlhttprequest=new XMLHttpRequest();
//code for IE7+, Firefox, Chrome, Opera, Safari
}
else{
xmlhttprequest=new ActiveXObject("Microsoft.XMLHTTP");
//code for IE6, IE5
}
//alert(xmlhttprequest);//说明获取对象成功
//与服务器建立连接,默认是true,异步，可以不写
xmlhttprequest.open("POST","${pageContext.request.contextPath}/sevletDemo2?time="+new Date().getTime(),true);
//向服务器发送请求数据，没有为null,传递数据是post请求的 如username=jack&password=123
//post提交时候，如果不是表单要加请求头，，因为servlet要request.getParams(),如果是表单就不要默认ectype就是
//在send()前加context-type
xmlhttprequest.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
var username=document.getElementById("username").value;
xmlhttprequest.send("username="+username);
xmlhttprequest.onreadystatechange=function(){
//alert(xmlhttprequest.readyState);4表示成功
//alert(xmlhttprequest.status);200表示成功
if(xmlhttprequest.readyState==4){
if(xmlhttprequest.status==200){
var mydiv=document.getElementById("mydiv");
mydiv.innerHTML=xmlhttprequest.responseText;
}
}
}
}
</script>
</body>
</html>
2：请求的 servlet对客户端提交的数据进行校验
public class sevletDemo2 extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
String username=request.getParameter("username");
PrintWriter writer=response.getWriter();
System.out.println(username);
if("jack".equals(username))
{
writer.write("用户名已存在");
}
else {
writer.write("可以注册");
}
}
时间： 2024-10-09 21:22:32