web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>Test</display-name> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>AjaxServlet</servlet-name> <servlet-class>one.AjaxServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>AjaxServlet</servlet-name> <url-pattern>/servlet/AjaxServlet</url-pattern> </servlet-mapping> </web-app>
ajax.html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Ajax测试</title>
</head>
<body>
<div>
<h2>AJAX Test</h2>
<input type="text" name="userinput" placeholder="用户输入，Ajax方式获得数据" onblur="getResult(this)">
<br>
<span id="ajax_result"></span>
<script>
getResult = function(str){
var httpxml;
if(0 == str.value.length) {
document.getElementById("ajax_result").innerHTML = "Nothing";
}
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
}else{
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function(){
if(4 == xmlhttp.readyState && 200 == xmlhttp.status) {
document.getElementById("ajax_result").innerHTML = xmlhttp.responseText;
}
}
xmlhttp.open("GET","/Test/servlet/AjaxServlet?userinput="+str.value,true);
xmlhttp.send();
}
</script>
</div>
</body>
</html>
实验结果
•长度小于6时：
•长度大于等于6：
使用JSP方式
receiveParams.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%
//接收参数
String userinput = request.getParameter("userinput");
//控制台输出表单数据看看
System.out.println("userinput =" + userinput);
//检查code的合法性
if (userinput == null || userinput.trim().length() == 0) {
out.println("code can't be null or empty");
} else if (userinput != null && userinput.equals("admin")) {
out.println("code can't be admin");
} else {
out.println("OK");
}
%>
