新建JavaWeb项目，新建a.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'a.jsp' starting page</title>
<Meta http-equiv="pragma" content="no-cache">
<Meta http-equiv="cache-control" content="no-cache">
<Meta http-equiv="expires" content="0">
<Meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<Meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<script type="text/javascript">
var xmlHttp = false;
try {
xmlHttp = new ActiveObject("Msxml2.XMLHTTP");
} catch (e) {
try {
xmlHttp = new ActiveObject("Microsoft.XMLHTTP");
} catch (e) {
xmlHttp = false;
}
}
if (!xmlHttp && typeof XMLHttpRequest != 'undefined') {
xmlHttp = new XMLHttpRequest();
}
function callServer(){
var city = document.getElementById("city").value;
var url = "b.jsp?city="+city;
xmlHttp.open("GET",url,true);
xmlHttp.onreadystatechange = updatePage;
xmlHttp.send(null);
}
function updatePage(){
if(xmlHttp.readyState == 4){
var response = xmlHttp.responseText;
document.getElementById("check").innerHTML = response;
}
}
</script>
</head>
<body>
城市：<input type="text" id="city" onblur="callServer();" />*<a style="color: red;" id="check"></a><br/>
状态：<input type="text" id="state" onblur="" /><br/>
</body>
</html>
新建b.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String city = request.getParameter("city");
System.out.println(city);
if (city == null || city.trim().equals("")) {
out.print("城市名不能为空！");
} else {
out.print("OK!");
}
%>
原文链接：https://www.f2er.com/ajax/162763.html
