使用OkHttp上传图片到服务器

Okhttp上传图片方法，就像网页那样，使用Form的Post。

首先创建requestBody，然后Builder构建Query：最后Response返回服务器请求，最后把response.body().string()转换成String格式，

不算很难，不详解。

    // 上傳圖片
    private String uploadResult;
    public String uploadImage(String URL, String userId, File file, String fileName) {
        try {
            // MultipartBuilder，是上传文件的query
            // addFormDataPart方法：@param [String]name, [String]value
            // addFormDataPart方法：@param [String]name, [String]fileName, [String]fileType, [String]file
            RequestBody requestBody = new MultipartBuilder()
                    .type(MultipartBuilder.FORM)
                    .addFormDataPart("portrait", fileName,
                            RequestBody.create(MediaType.parse("image/jpg"), file))
                    .addFormDataPart("userId", userId)
                    .addFormDataPart("action", "updateProtrait")
                    .build();

            // request方法： @param [String]URL, [RequestBody]requestBody
            Request request = new Request.Builder()
                    .url(URL)
                    .post(requestBody)
                    .build();

            // response储存服务器的回应
            Response response = okHttpClient.newCall(request).execute();
            // 把response转换成string
            uploadResult = response.body().string();

        } catch (IOException e) {
            uploadResult = e.toString();
        }
        return uploadResult;
    }

2. 这里是调用OkHttp上传照片方法，叁数是File类型。里面还有其他逻辑，自己叁透一下。

    private String updatePortraitURL;
    private UserDTO userDTO;
    private ResultDTO resultDTO;
    private String userId;
    private String userName;
    private String updatePortraitResult;
    private File filePortrait;
    private void updatePortrait() {
        // Network thread
        new Thread(new Runnable() {
            @Override
            public void run() {

                // get update protrait URL
                updatePortraitURL = Configuration.updatePortrait;
                // get user id
                userDTO = userDAO.getUser();
                userId = Integer.toString(userDTO.getId());
                userName = userDTO.getName();
                // convert bitmap to file
                filePortrait = convertBitmapToFile(protrait);
                // update via network
                updatePortraitResult = okhttp.uploadImage(updatePortraitURL, userId,filePortrait,userName);
                // gson
                resultDTO = gsonTools.getResult(updatePortraitResult);

                // UI Thread
                UploadPortraitActivity.this.runOnUiThread(new Runnable() {
                    public void run() {
                        // you can output to see the response from backend
                        // tvUploadPortrait.setText(resultDTO.toString());

                        if ( (resultDTO.getResult()).equals(1) )
                        {
                            tvUploadPortrait.setText("上傳照片成功。");
                        } else {
                            tvUploadPortrait.setText("上傳照片失敗。");
                        }
                        UploadPortraitActivity.this.finish();
                    }
                });

            }
        }).start();
    }

3. 这里有一个很重要的方法，把BitMap转换成File，那OkHttp才能构成requestBody。

    // convert bitmap to file
    private File f;
    private File convertBitmapToFile(Bitmap bitmap) {
        try {
            // create a file to write bitmap data
            f = new File(UploadPortraitActivity.this.getCacheDir(), "portrait");
            f.createNewFile();

            // convert bitmap to byte array
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            bitmap.compress(Bitmap.CompressFormat.PNG, 0 /*ignored for PNG*/, bos);
            byte[] bitmapdata = bos.toByteArray();

            // write the bytes in file
            FileOutputStream fos = new FileOutputStream(f);
            fos.write(bitmapdata);
            fos.flush();
            fos.close();
        } catch (Exception e) {

        }
        return f;
    }

4. 还有就是提权，能获取手机SD卡的相片。

首先，IsHavingPermissionStorage是先允许应用能存取手机内的数据。

然后，getImageFromGalery里的startActivityForResult(intent, RESULT_LOAD_IMAGE)是从相册中选择照片，最后调用onActivityResult。

这里不复杂，不详述，自己叁透一下。

    // check Permission
    private void IsHavingPermissionStorage() {
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
            // you can output the permission state
            // tvUploadPortrait.setText("能存取內置記憶體資料！");
        } else {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission. READ_EXTERNAL_STORAGE}, RESULT_LOAD_IMAGE);
        }
    }

    // get image
    private void getImageFromGalery() {
        intent = new Intent(Intent.ACTION_PICK,android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
        startActivityForResult(intent, RESULT_LOAD_IMAGE);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == RESULT_LOAD_IMAGE && resultCode == Activity.RESULT_OK && data != null) {
            // get Image URL
            Uri selectedImage = data.getData();
            String[] filePathColumns = {MediaStore.Images.Media.DATA};
            Cursor c = getContentResolver().query(selectedImage, filePathColumns, null, null, null);
            c.moveToFirst();
            int columnIndex = c.getColumnIndex(filePathColumns[0]);
            String imagePath = c.getString(columnIndex);

            // change image URL to Bitmap
            BitmapFactory.Options options = new BitmapFactory.Options();
            options.inPreferredConfig = Bitmap.Config.ARGB_8888;
            protrait  = BitmapFactory.decodeFile(imagePath, options);

            // you can output the selectedImage and imagePath
            // tvUploadPortrait.setText("selectedImage : "+selectedImage+"\n\n imagePath: "+imagePath);

            // set ImageView
            if (protrait  == null) {
                ivUploadProtrait.setImageResource(R.drawable.ic_portrait);
            } else {
                ivUploadProtrait.setImageBitmap(protrait);
            }

            c.close();
        }
    }