发送json数据的代码如下： 

public static void sendRequestWithOkHttp(List<Long>time,List<Float> x,List<Float> y,List<Float> z) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                List<JSONObject> mList = new ArrayList<>();
                try {
                    for (int i = 0; i < time.size(); i++) {
                        JSONObject obj = new JSONObject();
                        obj.put("accelerationX", x.get(i));
                        obj.put("accelerationY",y.get(i));
                        obj.put("accelerationZ",z.get(i));
                        obj.put("timestamp",time.get(i));
                        mList.add(obj);
                    }
                } catch (JSONException e) {
                }
//                System.out.println(obj);
                MediaType type = MediaType.parse("application/json;charset=utf-8");
                RequestBody RequestBody2 = RequestBody.create(type,mList.toString());
                try {
                    OkHttpClient client = new OkHttpClient();
                    Request request = new Request.Builder()
                            // 指定访问的服务器地址
                            .url("https://www.httpbin.org/post").post(RequestBody2)
                            .build();
                    Response response = client.newCall(request).execute();
                    String responseData = response.body().string();
                    System.out.println(responseData);
                    flag = true;
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }

json数据格式为：

上传文件： 

 public void upload() {
        new Thread(){
            @Override
            public void run() {
                File file = new File("/mnt/sdcard/加速度数据");
                MultipartBody multipartBody = new MultipartBody.Builder()
                        .addFormDataPart("加速度数据",file.getName(), RequestBody.create(file, MediaType.parse("text/plain")))
                        .build();
                Request request = new Request.Builder().url("https://www.httpbin.org/post").post(multipartBody).build();
                Call call = mOkHttpClient.newCall(request);
                try {
                    Response response = call.execute();
                    Log.i(TAG, "upload: "+response.body().string());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }.start();
    }