在第二个 ajax 请求后覆盖表中的数据答案

【问题标题】：override data in table after second ajax request在第二个 ajax 请求后覆盖表中的数据
【发布时间】：2017-08-08 15:26:35
【问题描述】：

我有带有要单击的按钮的 html 页面，它发送 ajax 请求并在表格中显示用户列表，这很好，我已经开发了这部分，但问题是当我再次尝试单击按钮时，数据被添加像这样的旧数据之后的表：

image

我想用新数据覆盖旧数据。

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <script src="jquery-3.2.1.min.js" type="text/javascript"></script>
            <link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/css/bootstrap.min.css">
    </head>    
    <body>
        <button id="but">click me </button>
        <div id="test">
            <table class="table table-stripped" id="table" style="border: 1px">


            </table>
        </div>
        <script>

            $(document).on("click", "#but", function () {  // When HTML DOM "click" event is invoked on element with ID "somebutton", execute the following function...
                $.get("testServlet", function (responseJson) {    // Execute Ajax GET request on URL of "someservlet" and execute the following function with Ajax response JSON...
                    var $ul = $("#table") // Create HTML <ul> element and append it to HTML DOM element with ID "somediv".
                    console.log(responseJson);
                    $.each(responseJson, function (index, item) { // Iterate over the JSON array.
                       $("<tr>").appendTo($ul)
                                .append($("<td>").text(item.id).appendTo($ul))// Create HTML <li> element, set its text content with currently iterated item and append it to the <ul>.
                                .append($("<td>").text(item.fname).appendTo($ul))
                                .append($("<td>").text(item.lname).appendTo($ul));
                    });                    
                });
            });
        </script>
    </body>
</html>

servlet 处理 ajax 请求：

 protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        user u = new user(1, "john", "doe");
        user u1 = new user(2, "foo", "foo");
        user u2 = new user(3, "bar", "bar");

        List<user> list = new ArrayList<>();
        list.add(u);
        list.add(u1);
        list.add(u2);
        String json = new Gson().toJson(list);

        response.setContentType("application/json");
        response.setCharacterEncoding("UTF-8");
        response.getWriter().write(json);
    }

【问题讨论】：

标签： jquery ajax servlets

【解决方案1】：

问题是append 每次将新数据附加到旧数据时尝试此解决方案：

   <script>

    $(document).on("click", "#but", function () {  // When HTML DOM "click" event is invoked on element with ID "somebutton", execute the following function...
        $.get("testServlet", function (responseJson) {    // Execute Ajax GET request on URL of "someservlet" and execute the following function with Ajax response JSON...
            var $ul = $("#table") // Create HTML <ul> element and append it to HTML DOM element with ID "somediv".
            console.log(responseJson);
            $('#table').html("");

            $.each(responseJson, function (index, item) { 
               $("<tr>").appendTo($ul)
                        .append($("<td>").text(item.id).appendTo($ul))// Create HTML <li> element, set its text content with currently iterated item and append it to the <ul>.
                        .append($("<td>").text(item.fname).appendTo($ul))
                        .append($("<td>").text(item.lname).appendTo($ul));
            });                    
        });
    });
</script>

【讨论】：