Ajax verifies the uniqueness of the user _ajax related

For beginners, learning Ajax to verify the user's unique combat is to consolidate Ajax,jquery,json and Struts2 basic knowledge, specific content as follows

Browse Effects Chart:

So we'll start with the following steps :

1. First, we first import the required packages and documents

Json Package:

STRUTS2 Package:

Introduce the Jquery-2.1.1.min.js file.

<script type= "Text/javascript" src= "Js/jquery-2.1.1.min.js" ></script>

2. Then, we need to configure the STRUTS2 filter in the Web.xml file

<filter>
 <filter-name>struts2</filter-name>
 <filter-class> Org.apache.struts2.dispatcher.ng.filter.strutsprepareandexecutefilter</filter-class>
 </filter>
 <filter-mapping>
 <filter-name>struts2</filter-name>
 <url-pattern>/*</ Url-pattern>
 </filter-mapping>

3. Then, start to write our login.jsp page, of course, you can add some CSS style to make it more beautiful. (I just did it a little bit low)

<div class= "Row" >
  
 

4. Then we started to write the action.

Verifies the uniqueness of the user public
void Isexist () throws IOException {
  Boolean exist = Name.equals ("John");
  Jsonobject result=new jsonobject ();
  if (exist) {
   result.put ("exist", true);
  } else{
   result.put ("exist", false);
  Servletactioncontext.getresponse (). setContentType ("Text/html;charset=utf-8");
  PrintWriter out=servletactioncontext.getresponse (). getwriter ();
  Out.println (Result.tostring ());
  Out.flush ();
  Out.close ();
 }

5. Finally, the preparation of struts.xml documents

<package name= "User" namespace= "/" extends= Struts-default "> <action name=" user_* "  
 class=" Com.ddge.action.UserAction "method=" {1} ">
  <result name=" error ">/login.jsp</result>
 < /action>
</package>

Summarize

Start deployment, test! The effect is not just out.

The above is the entire content of this article, I hope to help you learn.