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Code used to simulate the communication between the jQuery ajax server and the client

Source: Internet
Author: User
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Functions:

If the user name is blank, the system prompts "the user name cannot be blank"

If the user name prompts "user name [xxxxxx] already exists, use another user name, 4"

If the user name does not exist, the message "user name [xxxxxx] does not exist, you can use this user name to register, 5"

The running effect is as follows:

Directory structure: server-side AjaxServer Copy codeThe Code is as follows: package com. ljq. test;
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. Take the Parameter
String param = request. getParameter ("name ");
String name = URLDecoder. decode (param, "UTF-8 ");
// 2. Check whether the parameter is valid
If (param = null | param. length () = 0 ){
Out. println ("the user name cannot be blank ");
} Else {
// 3. Verification
If (name. equals ("linjiqin ")){
// 4. Return result data
Out. println ("username [" + name + "] already exists. Please use another username," + temp );
} Else {
Out. println ("user name [" + name + "] does not exist. You can use this user name to register," + temp );
}
}
} Catch (Exception e ){
E. printStackTrace ();
}
}
@ Override
Protected void doPost (HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
DoGet (request, response );
}
}

Configure web. xmlCopy codeThe Code is as follows: <? Xml version = "1.0" encoding = "UTF-8"?>
<Web-app version = "2.4" xmlns = "http://java.sun.com/xml/ns/j2ee"
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>
<Servlet>
<Servlet-name> AjaxServer </servlet-name>
<Servlet-class> com. ljq. test. AjaxServer </servlet-class>
</Servlet>
<Servlet-mapping>
<Servlet-name> AjaxServer </servlet-name>
<Url-pattern>/servlet/ajaxServer </url-pattern>
</Servlet-mapping>
<Welcome-file-list>
<Welcome-file> index. jsp </welcome-file>
</Welcome-file-list>
</Web-app>

Index. jsp pageCopy codeThe Code is as follows: <% @ page language = "java" import = "java. util. *" pageEncoding = "UTF-8" %>
<%
String path = request. getContextPath ();
String basePath = request. getScheme () + ": //" + request. getServerName () + ":" + request. getServerPort () + path + "/";
%>
<! Doctype html public "-// W3C // dtd html 4.01 Transitional // EN">
<Html>
<Head>
<Base href = "<% = basePath %>">
<Title> My JSP 'index. jsp 'starting page </title>
<Meta http-equiv = "pragma" content = "no-cache">
<Meta http-equiv = "cache-control" content = "no-cache">
<Meta http-equiv = "expires" content = "0">
<Meta http-equiv = "keywords" content = "keyword1, keyword2, keyword3">
<Meta http-equiv = "description" content = "This is my page">
<Script type = "text/javascript" src = "<% = request. getContextPath () %>/js/jquery-1.3.1.js"> </script>
<Script type = "text/javascript" src = "<% = request. getContextPath () %>/js/validate. js"> </script>
</Head>
<Body>
<! -- Html5 standard: first, the tag name must be in lower case, and then the tag must be closed. The third attribute name follows the camel naming method. The fourth attribute value must be in double quotation marks. -->
Enter the User name: <br/>
<Input id = "userName"/>
<Input type = "button" value = "Verification" onclick = "verify ();"/>
<Div id = "result"> </div>
</Body>
</Html>

Validate. jsCopy codeThe Code is as follows: function verify (){
// Solve the Chinese garbled Method 1: The page side of the data for an encodeURI, server segment using new String (name. getBytes ("iso8859-1"), "UTF-8 ");
// Solve Chinese garbled Method 2: data sent by the page for two encodeURI, the server segment uses URLDecoder. decode (name, "UTF-8 ")
Var url = "servlet/ajaxServer? Name = "+ encodeURI ($ (" # userName "). val ()));
// Do not add "/" before the url; otherwise, the url cannot be accessed.
// Var url = "/servlet/ajaxServer? Name = "+ encodeURI ($ (" # userName "). val (); // Error
Url = convertURL (url );
$. Get (url, null, function (data ){
$ ("# Result" pai.html (data );
});
}
// Add a timestamp to the url address. The browser is cheated and the cache is not read.
Function convertURL (url ){
// Obtain the timestamp
Var timstamp = (new Date (). valueOf ();
// Splice the timestamp information to the url
If (url. indexOf ("? ")> = 0 ){
Url = url + "& t =" + timstamp;
} Else {
Url = url + "? T = "+ timstamp;
}
Return url;
}

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

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