Ajax在Tapestry中的应用有哪些？

实例：

1. Ajax登录的优点：如果输入密码错误，页面无刷新。

<script language="javascript">

//定义XMLHttpRequest对象实例
var http_request = false;
//定义可复用的http请求发送函数
function send_request(method,url,content,responseType,callback) {//初始化、指定处理函数、发送请求的函数
http_request = false;
//开始初始化XMLHttpRequest对象
if(window.XMLHttpRequest) { //Mozilla 浏览器
http_request = new XMLHttpRequest();
if (http_request.overrideMimeType) {//设置MiME类别
http_request.overrideMimeType("text/xml");
}
}
else if (window.ActiveXObject) { // IE浏览器
try {
http_request = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try {
http_request = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {}
}
}
if (!http_request) { // 异常，创建对象实例失败
window.alert("不能创建XMLHttpRequest对象实例.");
return false;
}
if(responseType.toLowerCase()=="text") {
//http_request.onreadystatechange = processTextResponse;
http_request.onreadystatechange = callback;
}
else if(responseType.toLowerCase()=="xml") {
//http_request.onreadystatechange = processXMLResponse;
http_request.onreadystatechange = callback;
}
else {
window.alert("响应类别参数错误。");
return false;
}
// 确定发送请求的方式和URL以及是否异步执行下段代码
if(method.toLowerCase()=="get") {
http_request.open(method, url, true);
http_request.setRequestHeader("If-Modified-Since","0");
}
else if(method.toLowerCase()=="post") {
http_request.open(method, url, true);
http_request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
}
else {
window.alert("http请求类别参数错误。");
return false;
}
http_request.send(content);
}
// 处理返回文本格式信息的函数
function processTextResponse() {
if (http_request.readyState == 4) { // 判断对象状态
if (http_request.status == 200) { // 信息已经成功返回，开始处理信息
//alert(http_request.responseText);
alert("Text文档响应。");
} else { //页面不正常
alert("您所请求的页面有异常。");
}
}
}

function registerCheck() {
document.getElementById("feedback_info").innerHTML = "";
var f = document.forms[0];
if(f.userAccount.value!="" && f.password.value !="" ){
document.getElementById("feedback_info").innerHTML = "正在处理请求,请稍后...";
send_request("POST","?service=page/Register&userAccount="+f.userAccount.value+"&password="+f.password.value,null,"text",showFeedbackInfo);
}
else {
document.getElementById("feedback_info").innerHTML = "请输入正确的用户名和密码。";
}
}
function showFeedbackInfo() {
if (http_request.readyState == 4) { // 判断对象状态
//alert(http_request.responseText);
if (http_request.status == 200) { // 信息已经成功返回，开始处理信息
//alert(http_request.responseText);
if(http_request.responseText=='OK'){
document.forms[0].submit();
}
else{
document.getElementById("feedback_info").innerHTML = http_request.responseText;
}

} else { //页面不正常
alert("您所请求的页面有异常。");
}
}
}
</script>

2. Ajax实现定时刷新。（待续）