Question

我一直在研究如何创建一个文件，然后在内部存储中写入它几天，并且无法找到任何可行的或我能理解的内容。我之前从未做过这样的事情，所以我很遗憾。

根据android开发者网站页面，这段代码应该创建一个文件夹，如果它不存在，但是当我调用它时，它会给我一个错误。如果这意味着什么，该类扩展了SurfaceView。

public GameView(Context context) {
    super(context);

    gameLoopThread = new GameLoopThread(this);
    holder = getHolder();
    holder.addCallback(new Callback() {

        public void surfaceDestroyed(SurfaceHolder holder) {
            System.exit(1);
        }

        public void surfaceCreated(SurfaceHolder holder) {
            gameLoopThread.setRunning(true);
            gameLoopThread.start();
        }

        public void surfaceChanged(SurfaceHolder holder, int format,
                int width, int height) {

        }

    });

    createFile();

}

public void createFile() {
    String FILENAME = "hello_file";
    String string = "hello world!";

    FileOutputStream fos;
    try {
        fos = getContext().openFileOutput(FILENAME,Context.MODE_PRIVATE);
        fos.write(string.getBytes());
        fos.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

我想最终能做的就是在内部存储中创建一个文件，将整数（我的玩家在游戏中得分）保存到该文件中，然后才能加载和保存此

谢谢。

Answer 1

如果您想实现持久性键值对，我建议Android's SharedPreferences。使用SharedPreferences非常简单：

final SharedPreferences prefs = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE); //MY_PREFS_NAME could  be something useful, like username, so your data can be easily separated.

final static SCORE = "score"; //This variable simply holds the string "score", so we can tell the SharedPreferences which data we'd like.
int getScore() {
    return prefs.getInt(SCORE, 0); // second argument is default value if there is no value for key.
}

void setScore(int score) {
    Editor editor = prefs.edit();
    editor.putInt(SCORE, score);
    editor.commit();
}

这些设置将在您的应用程序的多次运行中持续存在。

Answer 2

这是我在本地编写和阅读照片文件的方式。可以应用类似的过程来处理不同类型的文件。只需使用不同的文件扩展名和不同的方法返回数据类型。

// Creates an ImageFile
private File createNewPhotoFile() throws IOException {

    String imageFileName = "JPEG";
    File storageDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
    File image = File.createTempFile(
            imageFileName,  /* prefix */
            ".jpg",         /* suffix */
            storageDir      /* directory */
    );

    // Save a file: path for use with ACTION_VIEW intents
    mCurrentPhotoPath = "file:" + image.getAbsolutePath();

    image.createNewFile();
    ByteArrayOutputStream stream = new ByteArrayOutputStream();
    FileOutputStream fo = new FileOutputStream(image);
    fo.write(stream.toByteArray());
    fo.close();


    return image;
}

// Retreave and convert from file to Bitmap
private Bitmap retreaveImageFromFile(ImageView target, File fileForPath) {

    // Get the dimensions of the View
    int targetW = target.getWidth();
    int targetH = target.getHeight();

    // Get the dimensions of the bitmap
    BitmapFactory.Options bmOptions = new BitmapFactory.Options();
    bmOptions.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(fileForPath.getAbsolutePath(), bmOptions);
    int photoW = bmOptions.outWidth;
    int photoH = bmOptions.outHeight;

    // Determine how much to scale down the image
    int scaleFactor = 4; //Math.min(photoW / targetW, photoH / targetH);

    // Decode the image file into a Bitmap sized to fill the View
    bmOptions.inJustDecodeBounds = false;
    bmOptions.inSampleSize = scaleFactor;

    Bitmap bitmap = BitmapFactory.decodeFile(newPhotoFile.getAbsolutePath(), bmOptions);

    return bitmap;
}

内部存储中的Android创建/写入文件

2 个答案: