获取内部和外部存储文件路径

Question

In my app, i need to read external as well as internal filepath. In other words, the user can select a file from internal storage if he desires or from sdcard if he so desires.

I found this while searching in SO:

Use getExternalStorageDirectory() to get access to external storage. Use getFilesDir() to get at your app's portion of internal storage.

But how would i know whether the user has chosen a file from external or internal directory?

Answer 1

Here is a sample method that reads an image from internal storage;

 public Bitmap readFromInternalStorage(String filename){
    try {
        File filePath = this.getFileStreamPath(filename);
        FileInputStream fi = new FileInputStream(filePath);
        return BitmapFactory.decodeStream(fi);
    } catch (Exception ex) { /* handle exception like a king here */}

    return null;
}

Now, what you could do from here is to see if the value is null and if so, then try to use a corresponding method to read from External Storage!

Of course, you can also have class variables to keep track of which source the image/file came from (internal or external) and update them accordingly depending on which method was called!

I hope this helps you solve this issue! Good luck.

Answer 2

But how would i know whether the user has chosen a file from external or internal directory?

That is up to you in your user interface. You are the one who is building the file-browsing UI, and so you know what root directory you used in your file-browsing UI.

Of course, there will not be any files in any of those locations, most likely.

getFilesDir() is part of internal storage , and the only files that will be in there will be ones that you place there yourself.

getExternalFilesDir() is part of external storage . In theory, the user could put files in this directory using other tools, like a desktop OS. In practice, the user is unlikely to do this, and nothing else is going to put files in that directory other than your code.

You are certainly welcome to write a file-browsing UI that uses other external storage locations, such as Environment.getExternalStoragePublicDirectory() , that are more likely to actually contain files.