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

The functions are as follows:

If the user name is empty, it will prompt "The user name cannot be empty"

If the username exists, it will prompt “Username [xxxxxx] already exists, please use another username, 4”                                                            

If the username does not exist, it will prompt "Username [xxxxxx] does not exist yet, you can use this username to register, 5"

The operation effect is as follows:

                                                 

Directory structure:

Server-side AjaxServer

Copy code The 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. 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

Copy code The code is as follows:

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-class>


AjaxServer
/servlet/ajaxServer


index.jsp
welcome-file-list>



index.jsp page

Copy code The code is as follows:

String path = request.getContextPath();
String basePath = request.getScheme() "://" request.getServerName() ":" request.getServerPort() path "/";
%>















请输入用户名：

validate.js

复制代码 代码如下:

function verify() {
// 解决中文乱码方法一： 页面端发出的数据作一次encodeURI，服务器段使用new String(name.getBytes("iso8859-1"),"UTF-8");
// 解决中文乱码方法二： 页面端发出的数据作两次encodeURI，服务器段使用URLDecoder.decode(name,"UTF-8")
var url = "servlet/ajaxServer?name=" encodeURI(encodeURI($("#userName").val()));
//注意url前不要加"/"，否则无法访问url
//var url = "/servlet/ajaxServer?name=" encodeURI(encodeURI($("#userName").val())); //错误
url = convertURL(url);
$.get(url, null, function(data) {
$("#result").html(data);
});
}
// 给url地址增加时间戳，骗过浏览器，不读取缓存
function convertURL(url) {
// 获取时间戳
var timstamp = (new Date()).valueOf();
// 将时间戳信息拼接到url上
if (url.indexOf("?") >= 0) {
url = url "&t=" timstamp;
} else {
url = url "?t=" timstamp;
}
return url;
}