简单的Ajax验证用户名

jsp页面：

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<Meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
<script type="text/javascript" src="${pageContext.request.contextPath }/scripts/jquery.js"></script>
<script type="text/javascript">
	$(function(){
		$(":input[name='username']").change(function(){
			var val = $(this).val();
			val = $.trim(val);
			
			if(val!=""){
				var url = "${pageContext.request.contextPath }/valiateUserName";
				//Servlet获得的参数名为userName
				var args = {"userName":val,"time":new Date()};
				
				$.post(url,args,function(data){
					$("#message").html(data);
				})
			}
		});
	})
</script>
</head>
<body>
	<form action="" method="post">
		UserName: <input type="text" name="username"/>
		<br>
		<div id="message"></div>
		<br>
		<input type="submit" value="Submit"/>	
	</form>

</body>
</html>

servlet:


import java.io.IOException;
import java.util.Arrays;
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;

/**
 * Servlet implementation class ValiateUserName
 */
@WebServlet("/valiateUserName")
public class ValiateUserName extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ValiateUserName() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request,HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException {
		// TODO Auto-generated method stub
		response.getWriter().append("Served at: ").append(request.getContextPath());
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request,HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request,IOException {
		List<String> userNames = Arrays.asList("aaa","bbb","ccc");
		String result = null;
		String username = request.getParameter("userName");
		if(userNames.contains(username)){
			result = "<font color='red'>该用户已经被使用</font>";
		}else{
			result = "<font color='green'>该用户可以使用</font>";
		}
		response.setContentType("text/html;charset=utf-8");
		response.setCharacterEncoding("utf-8");
		response.getWriter().print(result);
	}

}

原文链接：https://www.f2er.com/ajax/162572.html

简单的Ajax验证用户名

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