ajax 中用get方式和post方式提交的区别

注意：POST提交时,要多加一段代码:
xmlHttp.setrequestheader("content-length",post.length);
xmlHttp.setrequestheader("content-type","application/x-www-form-urlencoded");
否则也获取不到参数值
GET，POST提交示例:
var xmlHttp;
function ajaxSubmit(site)
{
createXMLHttpRequest();

//get提交
var keywords = escape(document.getElementById("keywords").value);//escape()解决中文参数
var url = "web.aspx?keywords="+keywords;
xmlHttp.open("get",url,true);
xmlHttp.onreadystatechange = callback;
xmlHttp.send(null);

//post提交
var keywords = escape(document.getElementById("keywords").value);
var url = "web.aspx";
var postdate = "keywords="+keywords;
xmlHttp.open("post",url,true);
xmlHttp.setrequestheader("content-length",postdate.length);//post提交设置项
xmlHttp.setrequestheader("content-type","application/x-www-form-urlencoded");//post提交设置项
xmlHttp.onreadystatechange = callback;
xmlHttp.send(postdate);
}
function createXMLHttpRequest()
{
if(window.ActiveXObject)
{
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
else if(window.XMLHttpRequest)
{
xmlHttp = new XMLHttpRequest();
}
}
function callback()
{
if(xmlHttp.readyState == 4)
{
if(xmlHttp.status == 200)
{
var dates = xmlHttp.responseText;
document.getElementById("obj").innerHTML=dates;
}
}else
{
document.getElementById("obj").innerHTML="正在加载数据,请稍等";
}
}