AJAX实践之与服务器通信(1)

GET
function doRequestUsingGET() {
　createXMLHttpRequest();
　var queryString = " GetAndPostExample? " ;
　queryString = queryString + createQueryString()+ 
" &timeStamp= " + new Date().getTime();
　xmlHttp.onreadystatechange = handleStateChange;
　xmlHttp.open( " GET " , queryString, true );
　xmlHttp.send( null );
} 
POST
function doRequestUsingPOST() {
　createXMLHttpRequest();
　var url = " GetAndPostExample?timeStamp= " + new Date().getTime();
　var queryString = createQueryString();
　xmlHttp.open( " POST " , url, true );
　xmlHttp.onreadystatechange = handleStateChange;
　xmlHttp.setRequestHeader( " Content-Type " , 
" application/x-www-form-urlencoded " ); 
　xmlHttp.send(queryString);
} 

import java.io. * ;
import java.net. * ;
import javax.servlet. * ;
import javax.servlet.http. * ;
public class GetAndPostExample extends HttpServlet {
　protected void processRequest(HttpServletRequest request,
HttpServletResponse response, String method)
throws ServletException, IOException {
// Set content type of the response to text/xml 
response.setContentType( " text/xml " );
// Get the user's input 
String firstName = request.getParameter( " firstName " );
String middleName = request.getParameter( " middleName " );
String birthday = request.getParameter( " birthday " );
// Create the response text 
String responseText = " Hello " + firstName + " " + middleName
+ " . Your birthday is " + birthday + " . " 
+ " [Method: " + method + " ] " ;
// Write the response back to the browser 
PrintWriter out = response.getWriter();
out.println(responseText);
// Close the writer 
out.close();
　} 
　protected void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
// Process the request in method processRequest 
processRequest(request, response, " GET " );
　} 
　protected void doPost(HttpServletRequest request, 
HttpServletResponse response)
throws ServletException, IOException {
// Process the request in method processRequest 
processRequest(request, response, " POST " );
　} 
} 　

function createXML() {
　var xml = "  " ;
　var options = document.getElementById( " petTypes " ).childNodes;
　var option = null ;
　for ( var i = 0 ; i < options.length; i ++ ) {
option = options[i];
if (option.selected) {
　xml = xml + "  " + option.value + "  " ;
} 
　} 
　xml = xml + "  " ;
　return xml;
} 
function sendPetTypes() {
　createXMLHttpRequest();
　var xml = createXML();
　var url = " PostingXMLExample?timeStamp= " + new Date().getTime();
　xmlHttp.open( " POST " , url, true );
　xmlHttp.onreadystatechange = handleStateChange;
　xmlHttp.setRequestHeader( " Content-Type " , 
" application/x-www-form-urlencoded " ); 
　xmlHttp.send(xml);
}