我試圖從我的請(qǐng)求中獲取值，但它返回 null。問題是什么？這是我的表格：    <form class="register-form">        <input class="name" type="text" placeholder="name"/>        <input class="password" type="password" placeholder="password"/>        <button id="register">create</button>    </form>我的發(fā)帖方法：    protected void doPost(HttpServletRequest req, HttpServletResponse resp) {        String name = req.getParameter("name");         if (Objects.isNull(projectService.getByName(name))) {            logger.info("Registration new project " + name); //NAME == NULL ???            String password = req.getParameter("password");            int budget = Integer.parseInt(req.getParameter("budget"));         ...        resp.setContentType("text/plain");        resp.setCharacterEncoding("UTF-8");        resp.getWriter().write("Success");    }和 JS 部分：$(document).ready(function () {    $("button#register").click(function () {        var name = $("form.register-form input.name").val();        var password = $("form.register-form input.password").val();        if (name == '' || password == '') {            alert("Please fill all fields...!!!!!!");        }  else {            var projectRegistration = {                projectName: name,                projectPassword: password            };            $.post("registration", projectRegistration, function (data) {                if (data === 'Success') {                    $("form")[0].reset();                }            });        }    });});我使用的是 Tomcat 版本 8.5.56