java - 如何将数据列表值从jsp传递到servlet

Question

我编写了一个jsp文件和servlet。在jsp中，我在表单中使用了数据列表。我想将用户输入传递给servlet。我已经发布了下面的代码。

jsp代码

 <form  action="NewServlet1" method="Post" >
<center>
        <input type="text" name="website" list="website" placeholder="Enter your website">
        <datalist id="website">
        <option value="https://www.google.lk/">GOOGLE</option>
        <option value="https://www.yahoo.com/">YAHOO</option>
        <option value="https://www.hackerrank.com/">HACKER RANK</option>

        </datalist><br><br><br>

    </center></form>

     <div style="width: 400px; height: 400px">
        <canvas id="myChart" width="1000" height="1000" ></canvas>
    </div>
<center> <div>
       <button id="button1"  name="button1" onclick="submit()" class="btn btn-primary">submit</button>
    </div></center>
    <script>
        function Test(today, time) {
            var ctx = new Chart(document.getElementById("myChart")

            , {

                type: 'line',
                data: {
                    labels: today,
                    datasets: [{
                            data: time,
                            label: "Web Service 1",
                            borderColor: "red",
                            fill: false
                        }
                    ]
                },
                options:
                        {
                            scales: {xAxes: [{display: true, scaleLabel: {display: true, labelString: 'date and time'}}], yAxes: [{display: true, ticks: {beginAtZero: true, steps: 100, stepValue: 50, max: 6000}}]},

                            hover: {intersect: false },
                            title: {display: true, text: 'response time of selected website'},
                              tooltips: { mode: 'nearest'}

                        }
            });
}
function submit()
{

    $.post("NewServlet1",
            {

            },
            function (data)
            {

                Test(data.today, data.time);
            });
}

servlet 代码

 protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

       response.setContentType("text/html;charset=UTF-8");

       String website = (String)request.getParameter("website");

但这不起作用。有人可以帮我解决这个问题吗？

Answer 1

首先，您需要将表单提交到路径映射到NewServlet1的servlet

<form  action="NewServlet1" method="Get" >
    <center>
            <input type="text" name="website" placeholder="Enter your website">
            <datalist id="website">
            <option value="https://www.google.lk/">GOOGLE</option>
            <option value="https://www.yahoo.com/">YAHOO</option>
            <option value="https://www.hackerrank.com/">HACKER RANK</option>

            </datalist>
    </center>
        <%
        String website= request.getParameter("website"); // it is not needed
        request.setAttribute("website",website);         // it is not needed
        %>
    <input type="submit"/> <!--need to add submit button to submit it to the servlet-->
</form>

现在您的 servlet 代码就很好了:

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("text/html;charset=UTF-8");
    String website = (String)request.getParameter("website");
}

注意:需要在website文本框中写入一些值

或者，如果您想获取先前存储在request对象中的attribute，则使用RequestDispatcher。