2008-04-29

第一个ajax例子【ajax有哪几种啊，了解的指导哈】

Ajax小例：登陆时验证用户是否存在，使用AJAX验证，无刷新
如果登陆成功则跳转到一个分页列表页面，使用AJAX实现分页效果


Action内的代码：

//返回该登陆页面，并予以错误提示信息
response.setContentType("application/xml"); //application/xml代表的是XML形式返回
response.setHeader("Cache-Control", "no-cache"); //设置不缓存

//组织返回数据
String xml="<?xml version=\"1.0\" encoding=\"gb2312\"?>";
xml+="<message>";
xml+="<info>";
xml+="<teacher><name>name01</name><age>20</age></teacher>";
xml+="<teacher><name>name02</name><age>20</age></teacher>";
xml+="<teacher><name>name03</name><age>20</age></teacher>";
xml+="</info>";
xml+="<returnmessage>";
xml+="<returnCode>9999</returnCode>";
xml+="</returnmessage>";
xml+="</message>";

PrintWriter pw=null;
try {
//获取页面写入器
pw=response.getWriter();
} catch (IOException e) {
e.printStackTrace();
}
pw.write(xml);
pw.flush();
pw.close();
return null;



JSP里解析获取数据：

<body>
<html:form action="/login.do?method=login" method="post">
<html:text property="username"></html:text>
<html:checkbox property="check" onclick="usernameCheck()">是否已经存在</html:checkbox>
<html:text property="password"></html:text>
<html:submit></html:submit>
<html:reset></html:reset>
<span id="checklogin"/>
</html:form><br><br><br></body>
<script>
var req; //定义全局变量
function usernameCheck()
{
var username=document.getElementById("username").value;
var password=document.getElementById("password").value;
var url="login.do?method=login&username="+username+"&password="+password;

if(window.XMLHttpRequest)
{
req=new XMLHttpRequest();
}
else if(window.ActiveXObject)
{
req=new ActiveXObject("Microsoft.XMLHttp");
}
if(req){
req.open("get",url,true);
req.onreadyStatechange=callback; //调用回调函数
req.send(null);
}
return false;
}

function callback()
{
if(req.readyState==4) //加载完毕
{
if(req.status==200)
{
parseMessage(); //解析数据
}
else
{
alert(req.status);
alert('Not able to litrieve description');
}
}
else
{
//正在加载
document.getElementById("checklogin").innerHTML="正在加载........";
}
}

function parseMessage()
{
this.itemList = new Array();
var xmlDoc=req.responseXML.documentElement; //接收XML格式的数据
var messages=xmlDoc.getElementsByTagName("info");
var mlength=messages.length;
alert(mlength);
if(mlength>0)
{
var teacher=messages[0].getElementsByTagName("teacher");
for( var j=0;j<teacher.length;j++)
{
var name=teacher[j].getElementsByTagName("name")[0].firstChild.nodeValue;
var age=teacher[j].getElementsByTagName("age")[0].firstChild.nodeValue;
alert('No:0'+' name:'+name+'\nage:'+age);
this.itemList.push(new Array(name,age));
}
}

var returnmessage=xmlDoc.getElementsByTagName("returnmessage");
var returnCode=returnmessage[0].getElementsByTagName("returnCode")[0].firstChild.nodeValue;

alert(this.itemList.length);
document.getElementById("checklogin").innerHTML=returnCode;
}

</script>
评论
一场雨 2008-04-29
不是很了解这上面 post 和 get的区别
hzl091 2008-04-29
主要是QQ的天气预报
hzl091 2008-04-29
<html>
<head>
<meta content="text/html; charset=gb2312" http-equiv="Content-Type">
<link rel="stylesheet" href="http://weather.qq.com/7v/css/wz1.css" type="text/css">
</head>
<script>
var req = false;

var ajax = function(){
this.method = 'GET';
this.url = '';
this.postData = null;
this.callBack = null;

this.create = function(){
if(window.XMLHttpRequest){
req = new XMLHttpRequest();
}
else if(window.ActiveXObject){
req = new ActiveXObject('Microsoft.XMLHttp');
}
}

this.sendReq = function(){
if(req){
req.open(this.method,this.url,true);
req.onreadystatechange = this.callBack;
if(this.method.toLowerCase() == 'post'){
req.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
}
req.send(this.postData);
}
else{
alert('ajax对象创建失败!!');
}
}
}


function callBack(){
var d = document.getElementById('d1');
if(req.readyState == 4){
if(req.status == 200){
if(d){
d.innerHTML = '';
d.innerHTML = req.responseText;
}

}
}
else if(req.readyState < 4){
if(d){
d.innerHTML = '';
d.innerHTML = '正在加载数据，请稍等...';
}
}
}

var a = new ajax();

function page_load(){
var city = [];
city[city.length] = {city_name:'北京',url:'http://weather.news.qq.com/inc/07_dc125.htm'}
city[city.length] = {city_name:'长沙',url:'http://weather.news.qq.com/inc/07_dc218.htm'}
city[city.length] = {city_name:'武汉',url:'http://weather.news.qq.com/inc/07_dc211.htm'}
city[city.length] = {city_name:'哈尔滨',url:'http://weather.news.qq.com/inc/07_dc17.htm'}
city[city.length] = {city_name:'长春',url:'http://weather.news.qq.com/inc/07_dc103.htm'}
city[city.length] = {city_name:'广州',url:'http://weather.news.qq.com/inc/07_dc292.htm'}
city[city.length] = {city_name:'香港',url:'http://weather.news.qq.com/inc/07_dc1.htm'}

var se_city = document.getElementById('se');
if(se_city){
for(var i = 0 ; i < city.length ; i++){
se_city.options.add(new Option(city[i].city_name,city[i].url));
}
}


}


function se_change()
{
var se_city = document.getElementById('se');
var url = '';
if(se_city && se_city.options[se_city.selectedIndex].text != '请选择'){
url = se_city.options[se_city.selectedIndex].value+'?id='+Math.random();

a.method = 'GET';
a.url = url;
a.callBack = callBack;
a.create();
a.sendReq();
}
}



</script>

<body onload = 'page_load();'>
</body>
<div id = 'div_city'>
请选择城市:
<select id = 'se' onchange = 'se_change();'>
<option>请选择</option>
</select>
</div>
<div id = 'd1'>

</div>
</html>

这是我写的一个例子
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