使用 .post和 . p o s t 和 .get向服务器发送请求
HTML
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript" src="/jquery_ajax/js/jquery-1.8.3.js"></script>
<script type="text/javascript">
//页面加载完成后
$(function() {
//添加失焦事件
$("#username").blur(function() {
//获取录入的用户名
var usernamevalue = $("#username").val();
//向服务器发送请求
var url="/jquery_ajax/load";
//使用$.post完成操作
$.post(url,{"username":usernamevalue},function(data){
$("#username_span").html(data);
},"html");
//下面是$.get请求
$.get(url,{"username":usernamevalue},function(data){
$("#username_span").html(data);
},"html");
});
});
</script>
</head>
<body>
<input type="text" name="username" id="username"><span id="username_span"></span>
<br>
<input type="password" name="password">
<br>
</body>
</html>
LoginServlet
public class LoadServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 解决乱码
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
// 1.得到用户名
String username = request.getParameter("username");
// 2.判断用户名是否可以使用
if ("tom".equals(username)) {
// 用户名不可以使用
response.getWriter().write("<font color='red'>用户名被占用</font>");
} else {
// 用户名可以使用
response.getWriter().write("<font color='green'>用户名可以使用</font>");
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
web.xml
<servlet>
<description></description>
<display-name>LoadServlet</display-name>
<servlet-name>LoadServlet</servlet-name>
<!--
Class clazz = Class.forName("com.itheima.servlet.LoadServlet");
Object obj = clazz.newInstatnce();
// 反射去调用 doGet, doPost
-->
<servlet-class>com.itheima.servlet.LoadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoadServlet</servlet-name>
<url-pattern>/load</url-pattern>
</servlet-mapping>
