如何在servlet post（）控制器中获取React js发布请求数据

Question

下面的servlet代码不起作用，JSON对象的值变为空，而请求getparameter()的值为null，如何解决？

这是 React js 代码：

processFormData(data){
    console.log("BODY : data : "+ data);
    console.log("sending data to server....");
    return fetch("ServletReactWeb/register", {
        mode: 'no-cors',
        method: "POST",
        headers: {
            'Accept': 'application/json',
            'Content-Type': 'application/json',
        },
        body: { 
            loadProds: 1,
            test: JSON.stringify(data) // look here!
        }                  
    })
   //.then(res => res.json())
   //.then(resp => this.setState({user:resp}))

    .then(function (res) {
        if (res.ok) {
            alert("Request send Successfully!!!");
            console.log(res);
            return res.json();
        } else if (res.status == 401) {
            alert("Oops! ");
        }
    }, function (e) {
        alert("Error submitting form!");
    }).then(function(data){
        console.log(data)
    });
    //.then(data => alert(JSON.stringify(data, null, "\t")));     
};

使用控制器中的代码创建了一个servlet post方法，用于接收请求参数值。

这是 servlet 代码：

protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    // TODO Auto-generated method stub
    // doGet(req, resp);
    // readContent(req,resp);
    System.out.println("Request Data : "+req.getParameter("test"));
    StringBuffer jb = new StringBuffer();
    String line = null;
    try {
        BufferedReader reader = new BufferedReader(req.getReader());
        while ((line = reader.readLine()) != null) {
            jb.append(line);
        }           
        Gson gson = new Gson();
        String jsonObject =  gson.toJson(jb.toString());
        System.out.println("jsonObject : " + jsonObject);
    } catch (Exception e) {
        // crash and burn
        e.printStackTrace();
    }
}

解决此问题的确切servlet代码是什么？