【Java学习20170428】Ajax-优快云博客

本文链接：https://blog.youkuaiyun.com/linsila8121/article/details/71089667

本文介绍了一个简单的用户名验证系统，通过Java Web结合Ajax实现前端输入与后端校验的即时反馈。后端采用Servlet处理请求，从预设的用户名列表中检查用户名是否存在，并返回相应消息。

JavaWeb

Ajax

简单的用户名验证

package com.tx.test;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(value="/test")
public class Test extends HttpServlet{

	private static List<String> list =null;
	
	static{
		list = new ArrayList<String>();
		list.add("张三");
		list.add("李四");
		list.add("王二麻子");
		list.add("tx");
		list.add("admin");
	}
	
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		// TODO Auto-generated method stub
		System.out.println("Get");
		req.setCharacterEncoding("UTF-8");
		resp.setContentType("text/html;charset=UTF-8");
		String name = req.getParameter("name");
		PrintWriter pw = resp.getWriter();
		if(list.contains(name)){
			pw.println("账号已存在");
		}else{
			pw.println("该账号可以使用");
		}
		pw.flush();
		pw.close();
	}
	
}

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<script type="text/javascript" src="js/jquery-3.1.1.js"></script>
<script>
	$(document).ready(function() {
		$("#but").click(function() {
			$.ajax({
				url : "test",
				type : "GET",
				data : {
					name : $("#username").val()
				},
				success : function(result) {
					$("#show").text("成功："+result);
				},
				error:function(result){
					$("#show").text("失败："+result);
				}
			});
		});
	});
</script>
<body>
	<table>
		<tr>
			<td>账号：<input id="username" type="text">
			</td>
			<td>
				<span id="show"></span>
			</td>
		</tr>
		<tr>
			<td>密码：<input type="password">
			</td>
		</tr>
		<tr>
			<td><input id="but" type="button" value="检查"></td>
		</tr>
	</table>
</body>
</html>