ajax编程实践之与服务器通信

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1、AJAX编程实践之与服务器通信　　首先看下看下相对简单些的--向服务器发送一个包含有名/值对的简单查询串，在这种情况下XHP即可以用GET也可以用POST。GETfunctiondoRequestUsingGET(){　createXMLHttpRequest();　varqueryString="GetAndPostExample?";　queryString=queryString+createQueryString()+"&timeStamp="+newDate().getTime();　

2、xmlHttp.onreadystatechange=handleStateChange;　xmlHttp.open("GET",queryString,true);　xmlHttp.send(null);}POSTfunctiondoRequestUsingPOST(){　createXMLHttpRequest();　varurl="GetAndPostExample?timeStamp="+newDate().getTime();　varqueryString=createQueryStr

3、ing();　xmlHttp.open("POST",url,true);　xmlHttp.onreadystatechange=handleStateChange;　xmlHttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");　xmlHttp.send(queryString);}　　queryString就是名/值对的参数形式了（如name=LiLin&age=23）,在调用OPEN方法中，当请求方

4、法是用POST的时候为了确保服务器知道请求体中有请求参数，需要调用setRequestHeader，将Content-Type值设置为application/x-www-form-urlencoded.当然也可不放在请求体中（那就不要用POST啦！）　　此时server处理：importjava.io.*;importjava.net.*;importjavax.servlet.*;importjavax.servlet.http.*;publicclassGetAndPostExampleex

5、tendsHttpServlet{　protectedvoidprocessRequest(HttpServletRequestrequest,HttpServletResponseresponse,Stringmethod)throwsServletException,IOException{　　//Setcontenttypeoftheresponsetotext/xml　　response.setContentType("text/xml");　　//Gettheuser'sinput　　

6、StringfirstName=request.getParameter("firstName");　　StringmiddleName=request.getParameter("middleName");　　Stringbirthday=request.getParameter("birthday");　　//Createtheresponsetext　　StringresponseText="Hello"+firstName+""+middleName+".Yourbirthdayis"+

7、birthday+"."+"[Method:"+method+"]";　　//Writetheresponsebacktothebrowser　　PrintWriterout=response.getWriter();　　out.println(responseText);　　//Closethewriter　　out.close();　}　protectedvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)throw

8、sServletException,IOException{　　//ProcesstherequestinmethodprocessRequest　　processRequest(request,response,"GET");　}　protectedvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{　　//Processtherequestinm