Ajax_典型应用_验证用户名是否

发布时间：2020-12-16 03:33:27 所属栏目：百科来源：网络整理

导读：%@ 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"htmlheadmeta http-equiv="Content-Type" content="text/ht

<%@ 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}/js/jquery-1.7.2.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";
			  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/><br/>
	<div id="message"></div>
	<input type="submit" value="Submit"/>
</form>
</body>
</html>

package org.java.test;

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 ValiateUserNameServlet
 */
@WebServlet("/valiateUserName")
public class ValiateUserNameServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

    /**
     * Default constructor. 
     */
    public ValiateUserNameServlet() {
        // 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 userName=request.getParameter("userName");
		String result=null;
		if(userNames.contains(userName)){
			result="<font color='red'>aleady used</font>";
		}else{
			result="<font color='green'>可以使用</font>";
		}
		response.setContentType("text/html;charset=UTF-8");
		response.setCharacterEncoding("UTF-8");
		response.getWriter().print(result);
	}

}

（编辑：李大同）

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