ajax，jsp

第 11 屆 iThome 鐵人賽

DAY 7

自我挑戰組

練習程式系列第 7 篇

11th鐵人賽

tedtedtedtedted

2019-09-21 00:10:46

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jquery是JavaScript的一套函式庫
jquery裡面有一個東西叫ajax，可以提交按鈕不跳頁、部分畫面更新重整。
應該說用jquery裡面的ajax比較簡單，直接用JavaScript達成同樣目的比較難，參考:
輕鬆理解 Ajax 與跨來源請求

現在有:
JavaScript Fetch API 使用教學

先找js的cdn:

ajax每個項目的說明:
https://api.jquery.com/jquery.ajax/

練習1:部分重整(把html的內容替換掉):

refresh.html

<html>

<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title>refresh</title>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
</head>

<body>
    <p>有ajax。時間是：<span class="times"></span></p>

    <script>
        setInterval(function() {
            Autofresh();
        }, 2000);

        function Autofresh() {
            $.ajax({
                url: 'time.jsp',
                type: 'POST',
                //data: ,
                success: function(data) {
                    console.log('Submission was successful.');
                    console.log(data);
                    var start = data.indexOf("<times>");
                    var end = data.indexOf("</times>");
                    var times = data.substring(start + 7, end).trim();
                    $(".times").html("");
                    $(".times").html(times);
                },
                error: function(XMLHttpRequest, status, error) {
                    console.log(error)
                }
            })
        }
        Autofresh();
    </script>

</body>

</html>

time.jsp:

<%@ page pageEncoding="UTF-8" contentType="text/html; charset=UTF-8" %>
<%@ page import="java.util.*" %>
<%@ page import="java.text.*" %>
<times >
<%
      Date dNow = new Date( );
      SimpleDateFormat fd = new SimpleDateFormat ("yyyy-MM-dd");
      SimpleDateFormat ft = new SimpleDateFormat ("HH:mm:ss");
      String date = fd.format(dNow);
      String time = ft.format(dNow);
      out.println(date+"   "+time);
%> 
</times>

結果:

練習2:傳data到jsp:

pass_value.html

<html>

<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title>pass_value</title>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
</head>

<body>
    <script>
        setInterval(function() {
            Autofresh();
        }, 2000);

        function Autofresh() {
            $.ajax({
                url: 'get_value.jsp',
                type: 'POST',
                data: {
                    "HelloWorld": 'HelloWorld123',
                },
                success: function(data) {
                    console.log(data);
                },
                error: function(XMLHttpRequest, status, error) {
                    console.log(error)
                }
            })
        }
        Autofresh();
    </script>

</body>

</html>

get_value.jsp

<%@ page  pageEncoding="UTF-8" contentType="text/html; charset=UTF-8"  %>
<%
    String hello= request.getParameter("HelloWorld").trim();
    out.println(hello);
%>

結果(pass_value.html):