Code to simulate jQuery ajax server-side communication with the client_jquery

import java.io.IOException;
import java.io.PrintWriter;
import java.net.URLDecoder;
import javax.servlet.ServletException;
import javax.servlet.http .HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@SuppressWarnings("serial")
public class AjaxServer extends HttpServlet {
@ Override
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
try {
//Set page utf-8 encoding
response.setContentType("text/html; charset=utf-8");
PrintWriter out = response.getWriter();
Integer total = (Integer) request.getSession().getAttribute("total");
int temp = 0;
if (total == null) {
temp = 1;
} else {
temp = total.intValue() 1;
}
request.getSession().setAttribute ("total", temp);
// 1. Get parameters
String param = request.getParameter("name");
String name = URLDecoder.decode(param, "UTF-8") ;
// 2. Check whether the parameters are valid
if (param == null || param.length() == 0) {
out.println("Username cannot be empty");
} else {
// 3. Verification operation
if (name.equals("linjiqin")) {
// 4. Return result data
out.println("Username [" name "] already exists, please use another username, " temp);
} else {
out.println("Username [" name "] does not exist yet, you can use this username to register, " temp);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
protected void doPost( HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}


Configuration web.xml

xmlns:xsi="http://www.w3. org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/ web-app_2_4.xsd">

AjaxServer
com.ljq.test.AjaxServer


AjaxServer
/servlet/ajaxServer< /url-pattern>


index.jsp




index.jsp page