Question

我知道这个问题出现了很多，但我无法找到任何有助于我的解决方案。我从网页上下载了头像并将其保存在内部存储空间中。

在我的活动中：

            // check if user has an custom avatar
            if (!bet.getUser().getAvatar().isEmpty()) {
                // now check if we already downloaded the avatar
                InputStream fis = AvatarHandler.getAvatar(getApplicationContext(), bet.getUser().getID());
                if (fis != null) {
                    Bitmap bmp = BitmapFactory.decodeStream(fis);
                    System.out.println(bmp); // is always null
                    avatarView.setImageBitmap(bmp);
                }
                else {
                    // if not, download it
                    System.out.println(bet.getUser().getAvatar());
                    downloadAvatar(bet.getUser().getAvatar());
                }
            }
            else {
                // set default avatar
                avatarView.setImageResource(R.drawable.avatar);         
            }


private void downloadAvatar(String url) {
    AsyncHttpClient client = new AsyncHttpClient();
    client.get(url, new BinaryHttpResponseHandler() {
        @Override
        public void onSuccess(byte[] fileData) {
            // save avatar on internal storageasd
            AvatarHandler.saveAvatar(getApplicationContext(), fileData, bet.getUser().getID());

            // display avatar
            Bitmap bmp = BitmapFactory.decodeByteArray(fileData, 0, fileData.length);
            avatarView.setImageBitmap(bmp);   
        }
    });     
}

我的AvatarHandler类

public class AvatarHandler {
    private static String fileName = "avatar-";

    /**
     * Returns the InputStream of the avatar of the given userID. null is returned if no avatar is stored.
     * @param userID
     * @return string
     */
    public static InputStream getAvatar(Context context, int userID) {
        try {
            FileInputStream fis = context.openFileInput(fileName + String.valueOf(userID));
            InputStreamReader isr = new InputStreamReader(fis);
            BufferedReader bufferedReader = new BufferedReader(isr);

            StringBuilder sb = new StringBuilder();
            String line;
            while ((line = bufferedReader.readLine()) != null) {
                sb.append(line);
            }

            InputStream stream = new ByteArrayInputStream(sb.toString().getBytes("UTF-8"));

            return stream;
        }
        catch (IOException e) {
            e.printStackTrace();

        }

        return null;
    }

    /**
     * Stores the given avatar on internal storage.
     * @param context
     * @param data
     * @param userID
     */
    public static void saveAvatar(Context context, byte[] data, int userID) {
        try {
            FileOutputStream fos = context.openFileOutput(fileName + String.valueOf(userID), Context.MODE_PRIVATE);
            fos.write(data);
            fos.close();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }
    }

Answer 1

在使用openFileInput（）创建fis的try块中，删除所有进一步的代码并返回fis;

BitmapFactory.decodeStream返回null

1 个答案: