Android 파일 공유

파일 공유

- 앱 간의 파일을 공유할 때 데이타 경우는 Intent로 전송하는데
파일을 공유하고 싶을 때 사용
(파일의 콘텐츠 URI 전송하고 수신할 앱에 대해서만 임시 액세스 권한을 부여하고 자동 만료되도록)


FileProvider 지정
- 다른 앱으로 파일을 공유하기 위해 콘텐츠 URI를 생성에 사용할 권한을 지정함
- 앱이 공유할 수 있는 디렉토리를 지정하는 XML 파일의 이름도 지정함

    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
        package="com.example.myapp">
        <application
            ...>
            <provider
                android:name="androidx.core.content.FileProvider"
                android:authorities="com.example.myapp.fileprovider"
                android:grantUriPermissions="true"
                android:exported="false">
                <meta-data
                    android:name="android.support.FILE_PROVIDER_PATHS"
                    android:resource="@xml/filepaths" />
            </provider>
            ...
        </application>
    </manifest>


공유 가능 디렉토리 지정
- res/xml/filepaths.xml 추가

    <paths>
        <files-path path="images/" name="myimages" />
    </paths>

 content://com.example.myapp.fileprovider/myimages/default_image.jpg

위와같이 외부에서 사용할 수 있는 URI가 생성됨


공유 파일 요청

    requestFileIntent = new Intent(Intent.ACTION_PICK);
    requestFileIntent.setType("image/jpg");
    startActivityForResult(requestFileIntent, 0);

파일 정보 가져오기

   public void onActivityResult(int requestCode, int resultCode,
                Intent returnIntent) {
            // If the selection didn't work
            if (resultCode != RESULT_OK) {
                // Exit without doing anything else
                return;
            } else {
                // Get the file's content URI from the incoming Intent
                Uri returnUri = returnIntent.getData();
    // get the file's MIME type
    String mimeType = getContentResolver().getType(returnUri);
                /*
                 * Try to open the file for "read" access using the
                 * returned URI. If the file isn't found, write to the
                 * error log and return.
                 */
                try {
                    /*
                     * Get the content resolver instance for this context, and use it
                     * to get a ParcelFileDescriptor for the file.
                     */
                    inputPFD = getContentResolver().openFileDescriptor(returnUri, "r");

                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                    Log.e("MainActivity", "File not found.");
                    return;
                }
                // Get a regular file descriptor for the file
                FileDescriptor fd = inputPFD.getFileDescriptor();
                ...
            }
        }
    


참고 사이트
https://developer.android.com/training/secure-file-sharing?hl=ko 

파일 공유  |  Android 개발자  |  Android Developers

https://developer.android.com/training/secure-file-sharing/request-file?hl=ko