android選取系統相冊圖片后，識別圖中二維碼

項目中添加設備操作需要掃描二維碼，考慮到多種掃碼方式，也添加直接識別二維碼圖片的操作。

首先跳轉系統相冊選取圖片

        Intent intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
        startActivityForResult(intent, DEVICE_PHOTO_REQUEST);

接着將選取的圖片展示到界面

@Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        //用戶沒有進行有效的設置操作，返回
        if (requestCode == Activity.RESULT_CANCELED ){
            ToastUtil.showToast(AddDeviceActivity.this, R.string.cancel);
            return;
        }
        if (DEVICE_PHOTO_REQUEST == requestCode){
            if (null != data) {
                Uri selectedImage = data.getData();
                String[] filePathColumns = {MediaStore.Images.Media.DATA};
                String imagePath;
                Cursor c = this.getContentResolver().query(selectedImage, filePathColumns, null, null, null);
                if (c != null) {
                    c.moveToFirst();
                    int columnIndex = c.getColumnIndex(filePathColumns[0]);
                    imagePath = c.getString(columnIndex);
                    c.close();
                    
            Bitmap bm = BitmapFactory.decodeFile(imgPath);
            img_code.setImageBitmap(bm);
                } else {
                    ToastUtil.showToast(this, "圖片路徑為空");
                }
            }
        }
        super.onActivityResult(requestCode, resultCode, data);
    }
    

然后用第三包的方法解碼識別（需要導入'cn.bingoogolapple:bga-zxing:1.1.9@aar'），注意自己處理一下匿名 AsyncTask 內部類導致的Activity 泄漏問題

　　　　　img_code.setDrawingCacheEnabled(true);
        final Bitmap bmp = img_code.getDrawingCache();
        new AsyncTask<Void, Void, String>() {
            @Override
            protected String doInBackground(Void... params) {
                return QRCodeDecoder.syncDecodeQRCode(bmp);
            }

            @Override
            protected void onPostExecute(String result) {
                if (TextUtils.isEmpty(result)) {
                    Toast.makeText(AddDeviceActivity.this, "二維碼解析失敗", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(AddDeviceActivity.this, result, Toast.LENGTH_SHORT).show();
                }
            }
        }.execute();