An error always pops up when ajax returns verification. ajaxerror

An error always pops up when ajax returns verification. ajaxerror

Send a simple case:
Front-end:

<% @ Page language = "java" import = "java. util. *" pageEncoding = "UTF-8" %> <! Doctype html public "-// W3C // dtd html 4.01 Transitional // EN"> 
Background:

public class Login_Do extends HttpServlet {   public void doGet(HttpServletRequest request, HttpServletResponse response)       throws ServletException, IOException {       this.doPost(request, response);   }   public void doPost(HttpServletRequest request, HttpServletResponse response)       throws ServletException, IOException {     request.setCharacterEncoding("UTF-8");      response.setCharacterEncoding("UTF-8");     String name =request.getParameter("name");     String password = request.getParameter("password");     String js = "{\"name\":name,\"password\":password}";     PrintWriter out = response.getWriter();     JSONObject json = new JSONObject();     json.put("name",name);     out.print(json.toString());     response.getWriter().write(json.toString());   } }
Click to log on:

Solution:There are two possible error messages:
First:Url error. The value cannot be obtained directly in the background.
You can use firebug of Firefox to view the problem: If the response information is returned, it is not the problem.Case 2:
Returned data type error:
In my example, the returned data is accidentally printed twice. just delete the two sentences:

out.print(json.toString()); response.getWriter().write(json.toString());  
An error occurred. The information displayed in firebug is:



The above is the reason why an error always pops up when ajax is returned for verification. I hope it will help you solve this problem.
Articles you may be interested in:

 

 
  
Asp + Ajax simple client login verification
 
  
Check whether Ajax User Name authentication exists
 
  
Ajax Form Verification implementation code
 
  
Jquery ajax login verification implementation code
 
  
Use Jquery Ajax in Asp.net to detect User Registration (verify whether the user name is saved)
 
  
Implementation Code for verifying the existence of user names based on Ajax implemented by jQuery
 
  
Ajax real-time verification of user name/mailbox and other existing code Packaging
 
  
PHP + Ajax asynchronous communication Implements user name email verification (two methods)
 
  
Ajax verification issues in the formvalidator verification plug-in