compile 'com.squareup.okhttp3:okhttp:3.4.1'

protected void post_file(final String url, final Map<String, Object> map, File file) {
    OkHttpClient client = new OkHttpClient();
    // form 表单形式上传
    MultipartBody.Builder requestBody = new MultipartBody.Builder().setType(MultipartBody.FORM);
    if(file != null){
      // MediaType.parse() 里面是上传的文件类型。
      RequestBody body = RequestBody.create(MediaType.parse("image/*"), file);
      String filename = file.getName();
      // 参数分别为， 请求key ，文件名称 ， RequestBody
      requestBody.addFormDataPart("headImage", file.getName(), body);
    }
    if (map != null) {
      // map 里面是请求中所需要的 key 和 value
      for (Map.Entry entry : map.entrySet()) {
        requestBody.addFormDataPart(valueOf(entry.getKey()), valueOf(entry.getValue()));
      }
    }
    Request request = new Request.Builder().url("请求地址").post(requestBody.build()).tag(context).build();
    // readTimeout("请求超时时间" , 时间单位);
    client.newBuilder().readTimeout(5000, TimeUnit.MILLISECONDS).build().newCall(request).enqueue(new Callback() {
      @Override
      public void onFailure(Call call, IOException e) {
        Log.i("lfq" ,"onFailure");
      }

      @Override
      public void onResponse(Call call, Response response) throws IOException {
        if (response.isSuccessful()) {
          String str = response.body().string();
          Log.i("lfq", response.message() + " , body " + str);

        } else {
          Log.i("lfq" ,response.message() + " error : body " + response.body().string());
        }
      }
    });

  }

FormBody.Builder formBody = new FormBody.Builder();
if (map != null) {
  for (Map.Entry entry : map.entrySet()) {
    formBody.add(String.valueOf(entry.getKey()),String.valueOf(entry.getValue()));
  }
}