ajax交互

1.servlet get 

servlet:

response.setContentType("text/html;charset=utf-8");
PrintWriter out=response.getWriter();
out.write("hello ajax");
System.out.println("ServletDemo1执行了");

java:

<script type="text/javascript">
window.onload=function(){
document.getElementById("b1").onclick=function(){
var xhr=createXmlHttpRequest();
xhr.onreadystatechange=function(){
if(xhr.readyState==4){
if(xhr.status==200||xhr.status==304){
var data =xhr.responseText;
alert(data);
document.getElementById("d1").innerHTML=data;
}
}
}
xhr.open("GET","/ajaxdayday28/servlet/ServletDemo1?time="+new Date().getTime());
xhr.send(null);
};
}
function createXmlHttpRequest(){
var xmlHttp;
try{
xmlHttp=new XMLHttpRequest();
}catch(e){
try{
xmlHttp=new ActiveXobject("Msxml2.XMLHTTP");
}catch(e){
try{
xmlHttp=new ActiveXobject("Microsoft.XMLHTTP");
}catch(e){}
}
}
return xmlHttp;
}
</script>

2.servlet post

servlet:

String username= request.getParameter("username");
String pwd= request.getParameter("pwd");

java:

<script type="text/javascript">
window.onload=function(){
document.getElementById("b1").onclick=function(){
var xhr=createXmlHttpRequest();
xhr.onreadystatechange=function(){
if(xhr.readyState==4){
if(xhr.status==200||xhr.status==304){

}
}
}
xhr.open("POST","/ajaxdayday28/servlet/ServletDemo2?time="+new Date().getTime());
xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
xhr.send("username=admin&pwd=123");
};
}
function createXmlHttpRequest(){
var xmlHttp;
try{
xmlHttp=new XMLHttpRequest();
}catch(e){
try{
xmlHttp=new ActiveXobject("Msxml2.XMLHTTP");
}catch(e){
try{
xmlHttp=new ActiveXobject("Microsoft.XMLHTTP");
}catch(e){}
}
}
return xmlHttp;
}
</script>