使用ajax向服务器发送请求
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript" src="js/jquery-1.8.3.min.js" ></script>
<script type="text/javascript">
//页面加载完成后
$(function(){
$("#username").blur(function(){
var usernamevalue = $("#username").val();
//alert(usernamevalue)
var url = "/jquery_ajax/load";
$.ajax({
url:url,
data:{'username':usernamevalue},
type:"post",
dataType:"html",
success:function(data){
$("#username_span").html(data);
}
});
});
});
</script>
</head>
<body>
<input type="text" name="username" id="username" />
<span id="username_span"></span><br />
</body>
</html>服务端java代码编写
package com.niwotaxuexiba.servlet;
import java.io.IOException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoadServlet extends HttpServlet {
public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException{
//解决乱码问题
response.setContentType("text/html;charset=utf-8");
//得到用户名
String username = request.getParameter("username");
//判断用户名是否可用
if(("tom").equals(username)){
//用户名不可以使用
response.getWriter().write("用户名被占用");
}else{
//用户名可以使用
response.getWriter().write("用户名可以使用");
}
}
public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException{
doGet(request,response);
}
}
web.xml配置
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>jquery_ajax</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<display-name>LoadServlet</display-name>
<servlet-name>LoadServlet</servlet-name>
<servlet-class>com.niwotaxuexiba.servlet.LoadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoadServlet</servlet-name>
<url-pattern>/load</url-pattern>
</servlet-mapping>
</web-app>
