如何将图像上传到NodeJS服务器使用翻新Android

Question

我使用Android和nodejs express。我想上传图片到快递服务器。

我正在使用翻新版，并且想要在服务器中另存为multer。

但是req.files是未定义的。就这样返回标题

我认为req.files应该有东西可以使用multer ...

我该怎么办..？

这是我的Android改装代码。

    @Multipart
    @POST("/upload")
    Call<UploadObject> uploadFile(@Part MultipartBody.Part file, @Part("name") RequestBody name);

public class Main2Activity extends AppCompatActivity implements EasyPermissions.PermissionCallbacks {

    private static final String TAG = "UPLOAD";
    private static final int REQUEST_GALLERY_CODE = 200;
    private static final int READ_REQUEST_CODE = 300;
    private static final String SERVER_PATH = "http://52.231.67.203:3000";
    private Uri uri;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        Button selectUploadButton = (Button)findViewById(R.id.select_image);
        selectUploadButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent openGalleryIntent = new Intent(Intent.ACTION_PICK);
                openGalleryIntent.setType("image/*");
                startActivityForResult(openGalleryIntent, REQUEST_GALLERY_CODE);
            }
        });
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        EasyPermissions.onRequestPermissionsResult(requestCode, permissions, grantResults, Main2Activity.this);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if(requestCode == REQUEST_GALLERY_CODE && resultCode == Activity.RESULT_OK){
            uri = data.getData();
            if(EasyPermissions.hasPermissions(this, Manifest.permission.READ_EXTERNAL_STORAGE)) {
                String filePath = getRealPathFromURIPath(uri, Main2Activity.this);
                File file = new File(filePath);
                Log.d(TAG, "Filename " + file.getName());
                //RequestBody mFile = RequestBody.create(MediaType.parse("multipart/form-data"), file);
                RequestBody mFile = RequestBody.create(MediaType.parse("image/*"), file);
                MultipartBody.Part fileToUpload = MultipartBody.Part.createFormData("file", file.getName(), mFile);
                RequestBody filename = RequestBody.create(MediaType.parse("text/plain"), file.getName());
                Retrofit retrofit = new Retrofit.Builder()
                        .baseUrl(SERVER_PATH)
                        .addConverterFactory(GsonConverterFactory.create())
                        .build();
                HttpInterface uploadImage = retrofit.create(HttpInterface.class);
                Call<UploadObject> fileUpload = uploadImage.uploadFile(fileToUpload, filename);
                fileUpload.enqueue(new Callback<UploadObject>() {
                    @Override
                    public void onResponse(Call<UploadObject> call, Response<UploadObject> response) {
                        Toast.makeText(Main2Activity.this, "Response " + response.raw().message(), Toast.LENGTH_LONG).show();
                        Toast.makeText(Main2Activity.this, "Success " + response.body().getSuccess(), Toast.LENGTH_LONG).show();
                    }
                    @Override
                    public void onFailure(Call<UploadObject> call, Throwable t) {
                        Log.d(TAG, "Error " + t.getMessage());
                    }
                });
            }else{
                EasyPermissions.requestPermissions(this, getString(R.string.read_file), READ_REQUEST_CODE, Manifest.permission.READ_EXTERNAL_STORAGE);
            }
        }
    }
    private String getRealPathFromURIPath(Uri contentURI, Activity activity) {
        Cursor cursor = activity.getContentResolver().query(contentURI, null, null, null, null);
        if (cursor == null) {
            return contentURI.getPath();
        } else {
            cursor.moveToFirst();
            int idx = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA);
            return cursor.getString(idx);
        }
    }

    @Override
    public void onPermissionsGranted(int requestCode, List<String> perms) {
        if(uri != null){
            String filePath = getRealPathFromURIPath(uri, Main2Activity.this);
            File file = new File(filePath);
            RequestBody mFile = RequestBody.create(MediaType.parse("image/*"), file);
            MultipartBody.Part fileToUpload = MultipartBody.Part.createFormData("file", file.getName(), mFile);
            RequestBody filename = RequestBody.create(MediaType.parse("text/plain"), file.getName());
            Retrofit retrofit = new Retrofit.Builder()
                    .baseUrl(SERVER_PATH)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
            HttpInterface uploadImage = retrofit.create(HttpInterface.class);
            Call<UploadObject> fileUpload = uploadImage.uploadFile(fileToUpload, filename);
            fileUpload.enqueue(new Callback<UploadObject>() {
                @Override
                public void onResponse(Call<UploadObject> call, Response<UploadObject> response) {
                    Toast.makeText(Main2Activity.this, "Success " + response.message(), Toast.LENGTH_LONG).show();
                    Toast.makeText(Main2Activity.this, "Success " + response.body().toString(), Toast.LENGTH_LONG).show();
                }
                @Override
                public void onFailure(Call<UploadObject> call, Throwable t) {
                    Log.d(TAG, "Error " + t.getMessage());
                }
            });
        }
    }
    @Override
    public void onPermissionsDenied(int requestCode, List<String> perms) {
        Log.d(TAG, "Permission has been denied");
    }
}

和服务器app.js

var createError = require('http-errors');
var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var logger = require('morgan');
var fs = require('fs');
// const mongoose = require('mongoose');

var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');
var contentsRouter = require('./routes/contents');

var app = express();


// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');

app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', indexRouter);
app.use('/users', usersRouter);
app.use('/contents', contentsRouter);

app.post('/upload', function(req, res) {
  console.log(req.files)

});


// catch 404 and forward to error handler
app.use(function(req, res, next) {
  next(createError(404));
});

// error handler
app.use(function(err, req, res, next) {
  // set locals, only providing error in development
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});

module.exports = app;