创建新文件

Question

这就是我尝试这样做的方式：

public void SaveImageToMemory(Bitmap bitmap, String fileName){
    File outFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/ImageEncryptionDemo", fileName+".jpeg");
    try {
        outFile.getParentFile().mkdirs();
        outFile.createNewFile();
        FileOutputStream outStream = new FileOutputStream(outFile);

        bitmap.compress(Bitmap.CompressFormat.JPEG, 100, outStream);
        outStream.flush();
        outStream.close();

        Log.i("app", "Saved image to " + outFile.getAbsolutePath());
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (java.io.IOException e){
        e.printStackTrace();
    }
}

我不知道为什么它会抛出IOException，即使：

1. Android Manifest中的权限已授予
2. outFile.getParentFile().mkdirs();应确保创建所有必需的父目录
3. 下面的函数（取自android docs）返回true

/* Checks if external storage is available for read and write */
public boolean isExternalStorageWritable() {
    String state = Environment.getExternalStorageState();
    if (Environment.MEDIA_MOUNTED.equals(state)) {
        return true;
    }
    return false;
}

/* Checks if external storage is available to at least read */
public boolean isExternalStorageReadable() {
    String state = Environment.getExternalStorageState();
    if (Environment.MEDIA_MOUNTED.equals(state) ||
            Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
        return true;
    }
    return false;
}

AndroidManifest中的权限：

<manifest [...]>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"></uses-permission>

Answer 1

在第二行，你刚刚感到困惑。看看这个。

^ Cannot assign `4` to `test` because number [1] is incompatible with string [2].

在

    File outFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath() +"/ImageEncryptionDemo/" + fileName+".jpeg");

您必须使用+而不是逗号。