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<%@ 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>
<script type="text/javascript" src="js/validate.js"></script>
<title>Using Ajax for validation</title>
</head>
<body>
<h1>Ajax Validation Example</h1>
Birth date:<input type="text" size="10" id="birthDate" onchange="validate();"/>
<div id="dateMessage"></div>
</body>
</html>
var xmlHttp;
function createXMLHttpRequest() {
if(window.ActiveXObject) {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
else if(window.XMLHttpRequest) {
xmlHttp = new XMLHttpRequest();
}
}
function validate() {
createXMLHttpRequest();
var date = document.getElementById("birthDate");
var url = "ValidationServlet?birthDate=" + escape(date.value);//ValidationServlet必须在web.xml配置才能找到对应的的后台servlet
xmlHttp.open("GET", url, true);
xmlHttp.onreadystatechange = callback;
xmlHttp.send(null);
}
function callback() {
if(xmlHttp.readyState == 4) {
if(xmlHttp.status == 200) {
var mes = xmlHttp.responseXML.getElementsByTagName("message")[0].firstChild.data;
var val = xmlHttp.responseXML.getElementsByTagName("passed")[0].firstChild.data;
setMessage(mes, val);
}
}
}
function setMessage(message, isValid) {
var messageArea = document.getElementById("dateMessage");
var fontColor = "red";
if(isValid == "true") {
fontColor = "green";
}
messageArea.innerHTML = "<font color=" + fontColor + ">" + message + "</font>";
}
package com.lancekoo;
import java.io.IOException;
import java.io.PrintWriter;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ValidationServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
PrintWriter out = resp.getWriter();
boolean passed = validateDate(req.getParameter("birthDate"));
resp.setContentType("text/xml");
resp.setHeader("Cache-Control", "no-cache");
String message = "You have entered an invalid date.";
if(passed) {
message = "You have entered a valid date.";
}
out.println("<response>");
out.println("<passed>" + Boolean.toString(passed) + "</passed>");
out.println("<message>" + message + "</message>");
out.println("</response>");
out.close();
}
private boolean validateDate(String date) {
boolean isValid = true;
if(date != null) {
SimpleDateFormat formatter = new SimpleDateFormat("MM/dd/yyyy");
try {
formatter.parse(date);
} catch(ParseException e) {
System.out.println(e.toString());
isValid = false;
}
}
else {
isValid = false;
}
return isValid;
}
}
<?xml version="1.0" encoding="UTF-8"?>
<web-app>
<servlet>
<servlet-name>ValidationServlet</servlet-name>
<servlet-class>com.lancekoo.ValidationServlet</servlet-class>
</servlet>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>