Java 如何添加代码以等待响应？

我想知道在转到onPostExecute方法之前如何等待servlet的响应

请提供解决方案

编辑：编辑版本

Response responsed = null;

    @Override
    protected String doInBackground(String... strings) {
        ArrayList<Farm> farmSend= dbFarm.getAllFarms();

        String result = "";
        OkHttpClient client = new OkHttpClient();
        RequestBody postRequestBody = new FormBody.Builder()
                .add("farms", new Gson().toJson(farmSend))
                .add("dataToBeRetrieved", "getData")
                .build();

        Request request = new Request.Builder()
                .url(new ipconfig().getIp() + "MobileFarm")
                .post(postRequestBody)
                .build();

            try {
                client.newCall(request).enqueue(new Callback() {
                    @Override
                    public void onFailure(Call call, IOException e) {
                        e.printStackTrace();
                    }

                    @Override
                    public void onResponse(Call call, Response response) throws IOException {
                        if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

                        responsed = response;
                        Headers responHeaders = response.headers();
                        for (int i = 0, size = responHeaders.size(); i < size; i++) {
                            Log.i("response: ", responHeaders.name(i) + ": " + responHeaders.value(i));
                        }
                        Log.i("response body: ", response.body().toString());
                    }
                });
                result = responsed.body().string();
            } catch (IOException e) {
                e.printStackTrace();
            }
        return result;
    }

编辑：这是我的servlet代码

protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        int addCount = 0;
        int updateCount = 0;

        System.out.println("farmer input form mobile upload");
        ArrayList<Farmer> farmers = new Gson().fromJson(request.getParameter("farmers"), new TypeToken<List<Farmer>>() {
        }.getType());
        for (int a = 0; a < farmers.size(); a++) {
            if (a < new FarmerDAO().getListOfFarmers().size()) {
                if (new FarmerDAO().updateFarmer(farmers.get(a))) {
                    updateCount++;
                }
            } else if (new FarmerDAO().registerFarmer(farmers.get(a))) {
                addCount++;
            } else {
                System.out.println(farmers.get(a).getFarmerID() + " not added/updated");
            }
        }
        System.out.println("farmer input count updated: " + updateCount);
        System.out.println("farmer input count added: " + addCount);

        response.getWriter().write(new Gson().toJson("farmer input completed"));
    }

---

唯一可以立即打印的是农民从移动上传和启动循环中输入的内容。在收到任何响应之前，不会打印后续打印行。

使用okhttp提供的这些回调：

client.newCall(request).enqueue(new Callback() {
        @Override
        public void onFailure(Request request, IOException e) {

        }

        @Override
        public void onResponse(Response response) throws IOException {

        }
    });

您可以从库本身使用，这基本上是一个响应可用时的回调

从他们的文件

在工作线程上下载一个文件，并在响应可读时被回调。在响应头准备就绪后进行回调。读取响应主体可能仍然会阻塞。OkHttp目前不提供异步API来部分接收响应体

---

来源：

不知道你的意思是什么？您正在发送请求并获得响应。你还想等什么？@MuratK。我应该等待servlet响应。但是我收到了null，因为servlet还没有完成它的任务。好的，我想我理解你的意思。请参阅我的答案。03-22 20:47:54.964 20925-21675/com.example.josiah.bigassv2 E/AndroidRuntime:FATAL EXCEPTION:AsyncTask 3 Process:com.example.josiah.bigassv2，PID:20925由以下原因引起：java.lang.NullPointerException:尝试在null对象上调用虚拟方法“okhttp3.ResponseBody okhttp3.Response.body”reference@RubySenpaii你做了什么？用你的更改编辑你的开场白。

  private final OkHttpClient client = new OkHttpClient();

  public void run() throws Exception {
    Request request = new Request.Builder()
        .url("http://publicobject.com/helloworld.txt")
        .build();

    client.newCall(request).enqueue(new Callback() {
      @Override public void onFailure(Call call, IOException e) {
        e.printStackTrace();
      }

      @Override public void onResponse(Call call, Response response) throws IOException {
        if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

        Headers responseHeaders = response.headers();
        for (int i = 0, size = responseHeaders.size(); i < size; i++) {
          System.out.println(responseHeaders.name(i) + ": " + responseHeaders.value(i));
        }

        System.out.println(response.body().string());
      }
    });
  }