Erstellen Sie einen einfachen File Chooser in Android

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="org.o7planning.filechooserexample">

    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:dividerPadding="5sp"
    tools:context=".FileChooserFragment">

    <EditText
        android:id="@+id/editText_path"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:ems="10"
        android:inputType="textUri" />

    <Button
        android:id="@+id/button_browse"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="0"
        android:text="Browse" />
</LinearLayout>

package org.o7planning.filechooserexample;

import android.Manifest;
import android.app.Activity;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Bundle;

import androidx.core.app.ActivityCompat;
import androidx.fragment.app.Fragment;

import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class FileChooserFragment extends Fragment {

    private static final int MY_REQUEST_CODE_PERMISSION = 1000;
    private static final int MY_RESULT_CODE_FILECHOOSER = 2000;

    private Button buttonBrowse;
    private EditText editTextPath;

    private static final String LOG_TAG = "AndroidExample";

    @Override
    public View onCreateView(final LayoutInflater inflater, final ViewGroup container, final Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.fragment_file_chooser, container, false);

        this.editTextPath = (EditText) rootView.findViewById(R.id.editText_path);
        this.buttonBrowse = (Button) rootView.findViewById(R.id.button_browse);

        this.buttonBrowse.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                askPermissionAndBrowseFile();
            }

        });
        return rootView;
    }

    private void askPermissionAndBrowseFile()  {
        // With Android Level >= 23, you have to ask the user
        // for permission to access External Storage.
        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M) { // Level 23

            // Check if we have Call permission
            int permisson = ActivityCompat.checkSelfPermission(this.getContext(),
                    Manifest.permission.READ_EXTERNAL_STORAGE);

            if (permisson != PackageManager.PERMISSION_GRANTED) {
                // If don't have permission so prompt the user.
                this.requestPermissions(
                        new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
                        MY_REQUEST_CODE_PERMISSION
                );
                return;
            }
        }
        this.doBrowseFile();
    }

    private void doBrowseFile()  {
        Intent chooseFileIntent = new Intent(Intent.ACTION_GET_CONTENT);
        chooseFileIntent.setType("*/*");
        // Only return URIs that can be opened with ContentResolver
        chooseFileIntent.addCategory(Intent.CATEGORY_OPENABLE);

        chooseFileIntent = Intent.createChooser(chooseFileIntent, "Choose a file");
        startActivityForResult(chooseFileIntent, MY_RESULT_CODE_FILECHOOSER);
    }

    // When you have the request results
    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           String permissions[], int[] grantResults) {

        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        //
        switch (requestCode) {
            case MY_REQUEST_CODE_PERMISSION: {

                // Note: If request is cancelled, the result arrays are empty.
                // Permissions granted (CALL_PHONE).
                if (grantResults.length > 0
                        && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                    Log.i( LOG_TAG,"Permission granted!");
                    Toast.makeText(this.getContext(), "Permission granted!", Toast.LENGTH_SHORT).show();

                    this.doBrowseFile();
                }
                // Cancelled or denied.
                else {
                    Log.i(LOG_TAG,"Permission denied!");
                    Toast.makeText(this.getContext(), "Permission denied!", Toast.LENGTH_SHORT).show();
                }
                break;
            }
        }
    }


    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch (requestCode) {
            case MY_RESULT_CODE_FILECHOOSER:
                if (resultCode == Activity.RESULT_OK ) {
                    if(data != null)  {
                        Uri fileUri = data.getData();
                        Log.i(LOG_TAG, "Uri: " + fileUri);

                        String filePath = null;
                        try {
                            filePath = FileUtils.getPath(this.getContext(),fileUri);
                        } catch (Exception e) {
                            Log.e(LOG_TAG,"Error: " + e);
                            Toast.makeText(this.getContext(), "Error: " + e, Toast.LENGTH_SHORT).show();
                        }
                        this.editTextPath.setText(filePath);
                    }
                }
                break;
        }
        super.onActivityResult(requestCode, resultCode, data);
    }

    public String getPath()  {
        return this.editTextPath.getText().toString();
    }
}

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="5sp"
    android:paddingTop="5sp"
    android:paddingRight="5sp"
    android:paddingBottom="5sp"
    tools:context=".MainActivity" >

    <fragment
        android:id="@+id/fragment_fileChooser"
        android:name="org.o7planning.filechooserexample.FileChooserFragment"
        android:layout_width="0dp"
        android:layout_height="45dp"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginRight="16dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/button_showInfo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="Show Info"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/fragment_fileChooser" />
</androidx.constraintlayout.widget.ConstraintLayout>

package org.o7planning.filechooserexample;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.FragmentManager;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private FileChooserFragment fragment;
    private Button buttonShowInfo;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        FragmentManager fragmentManager = this.getSupportFragmentManager();
        this.fragment = (FileChooserFragment) fragmentManager.findFragmentById(R.id.fragment_fileChooser);

        this.buttonShowInfo = this.findViewById(R.id.button_showInfo);

        this.buttonShowInfo.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                showInfo();
            }
        });
    }

    private void showInfo()  {
        String path = this.fragment.getPath();
        Toast.makeText(this, "Path: " + path, Toast.LENGTH_LONG).show();
    }
}

package org.o7planning.filechooserexample;

import android.annotation.SuppressLint;
import android.content.ContentResolver;
import android.content.ContentUris;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.os.Build;
import android.os.Environment;
import android.provider.DocumentsContract;
import android.provider.MediaStore;
import android.provider.OpenableColumns;
import android.text.TextUtils;
import android.util.Log;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;

public class FileUtils {

    private static final String LOG_TAG = "FileUtils";

    private static Uri contentUri = null;

    /**
     * Get a file path from a Uri. This will get the the path for Storage Access
     * Framework Documents, as well as the _data field for the MediaStore and
     * other file-based ContentProviders.<br>
     * <br>
     * Callers should check whether the path is local before assuming it
     * represents a local file.
     *
     * @param context The context.
     * @param uri     The Uri to query.
     */
    @SuppressLint("NewApi")
    public static String getPath(final Context context, final Uri uri) {
        // Check here to KITKAT or new version
        final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
        String selection = null;
        String[] selectionArgs = null;
        // DocumentProvider
        if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
            // ExternalStorageProvider
            if (isExternalStorageDocument(uri)) {
                final String docId = DocumentsContract.getDocumentId(uri);
                final String[] split = docId.split(":");
                final String type = split[0];

                String fullPath = getPathFromExtSD(split);
                if (fullPath != "") {
                    return fullPath;
                } else {
                    return null;
                }
            }

            // DownloadsProvider
            else if (isDownloadsDocument(uri)) {
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                    final String id;
                    Cursor cursor = null;
                    try {
                        cursor = context.getContentResolver().query(uri, new String[]{MediaStore.MediaColumns.DISPLAY_NAME}, null, null, null);
                        if (cursor != null && cursor.moveToFirst()) {
                            String fileName = cursor.getString(0);
                            String path = Environment.getExternalStorageDirectory().toString() + "/Download/" + fileName;
                            if (!TextUtils.isEmpty(path)) {
                                return path;
                            }
                        }
                    } finally {
                        if (cursor != null) {
                            cursor.close();
                        }
                    }
                    id = DocumentsContract.getDocumentId(uri);
                    if (!TextUtils.isEmpty(id)) {
                        if (id.startsWith("raw:")) {
                            return id.replaceFirst("raw:", "");
                        }
                        String[] contentUriPrefixesToTry = new String[] {
                                "content://downloads/public_downloads",
                                "content://downloads/my_downloads"
                        };
                        for (String contentUriPrefix : contentUriPrefixesToTry) {
                            try {
                                final Uri contentUri = ContentUris.withAppendedId(Uri.parse(contentUriPrefix), Long.valueOf(id));

                                // final Uri contentUri = ContentUris.withAppendedId(
                                //        Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));

                                return getDataColumn(context, contentUri, null, null);
                            } catch (NumberFormatException e) {
                                // In Android 8 and Android P the id is not a number
                                return uri.getPath().replaceFirst("^/document/raw:", "").replaceFirst("^raw:", "");
                            }
                        }
                    }
                } else {
                    final String id = DocumentsContract.getDocumentId(uri);
                    final boolean isOreo = Build.VERSION.SDK_INT >= Build.VERSION_CODES.O;
                    if (id.startsWith("raw:")) {
                        return id.replaceFirst("raw:", "");
                    }
                    try {
                        contentUri = ContentUris.withAppendedId(
                                Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));

                    } catch (NumberFormatException e) {
                        e.printStackTrace();
                    }
                    if (contentUri != null) {
                        return getDataColumn(context, contentUri, null, null);
                    }
                }
            }
            // MediaProvider
            else if (isMediaDocument(uri)) {
                final String docId = DocumentsContract.getDocumentId(uri);
                final String[] split = docId.split(":");
                final String type = split[0];

                Uri contentUri = null;

                if ("image".equals(type)) {
                    contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
                } else if ("video".equals(type)) {
                    contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
                } else if ("audio".equals(type)) {
                    contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
                }
                selection = "_id=?";
                selectionArgs = new String[]{split[1]};

                return getDataColumn(context, contentUri, selection,
                        selectionArgs);
            } else if (isGoogleDriveUri(uri)) {
                return getDriveFilePath(uri, context);
            }
        }


        // MediaStore (and general)
        else if ("content".equalsIgnoreCase(uri.getScheme())) {

            if (isGooglePhotosUri(uri)) {
                return uri.getLastPathSegment();
            }

            if (isGoogleDriveUri(uri)) {
                return getDriveFilePath(uri, context);
            }
            if( Build.VERSION.SDK_INT == Build.VERSION_CODES.N) {
                // return getFilePathFromURI(context,uri);
                return getMediaFilePathForN(uri, context);
                // return getRealPathFromURI(context,uri);
            } else {
                return getDataColumn(context, uri, null, null);
            }
        }
        // File
        else if ("file".equalsIgnoreCase(uri.getScheme())) {
            return uri.getPath();
        }
        return null;
    }

    /**
     * Check if a file exists on device
     *
     * @param filePath The absolute file path
     */
    private static boolean fileExists(String filePath) {
        File file = new File(filePath);

        return file.exists();
    }


    /**
     * Get full file path from external storage
     *
     * @param pathData The storage type and the relative path
     */
    private static String getPathFromExtSD(String[] pathData) {
        final String type = pathData[0];
        final String relativePath = "/" + pathData[1];
        String fullPath = "";

        // on my Sony devices (4.4.4 & 5.1.1), `type` is a dynamic string
        // something like "71F8-2C0A", some kind of unique id per storage
        // don't know any API that can get the root path of that storage based on its id.
        //
        // so no "primary" type, but let the check here for other devices
        if ("primary".equalsIgnoreCase(type)) {
            fullPath = Environment.getExternalStorageDirectory() + relativePath;
            if (fileExists(fullPath)) {
                return fullPath;
            }
        }

        // Environment.isExternalStorageRemovable() is `true` for external and internal storage
        // so we cannot relay on it.
        //
        // instead, for each possible path, check if file exists
        // we'll start with secondary storage as this could be our (physically) removable sd card
        fullPath = System.getenv("SECONDARY_STORAGE") + relativePath;
        if (fileExists(fullPath)) {
            return fullPath;
        }

        fullPath = System.getenv("EXTERNAL_STORAGE") + relativePath;
        if (fileExists(fullPath)) {
            return fullPath;
        }

        return fullPath;
    }

    private static String getDriveFilePath(Uri uri, Context context) {
        Uri returnUri = uri;
        ContentResolver contentResolver = context.getContentResolver();
        Cursor returnCursor = contentResolver.query(returnUri, null, null, null, null);

        // Get the column indexes of the data in the Cursor,
        // move to the first row in the Cursor, get the data,
        // and display it.

        int nameIndex = returnCursor.getColumnIndex(OpenableColumns.DISPLAY_NAME);
        int sizeIndex = returnCursor.getColumnIndex(OpenableColumns.SIZE);
        returnCursor.moveToFirst();
        String name = (returnCursor.getString(nameIndex));
        String size = (Long.toString(returnCursor.getLong(sizeIndex)));
        File file = new File(context.getCacheDir(), name);
        try {
            InputStream inputStream = context.getContentResolver().openInputStream(uri);
            FileOutputStream outputStream = new FileOutputStream(file);
            int read = 0;
            int maxBufferSize = 1 * 1024 * 1024;
            int bytesAvailable = inputStream.available();

            // int bufferSize = 1024;
            int bufferSize = Math.min(bytesAvailable, maxBufferSize);

            final byte[] buffers = new byte[bufferSize];
            while ((read = inputStream.read(buffers)) != -1) {
                outputStream.write(buffers, 0, read);
            }
            Log.e("File Size", "Size " + file.length());
            inputStream.close();
            outputStream.close();
            Log.e("File Path", "Path " + file.getPath());
            Log.e("File Size", "Size " + file.length());
        } catch (Exception e) {
            Log.e(LOG_TAG, e.getMessage());
        }
        return file.getPath();
    }

    private static String getMediaFilePathForN(Uri uri, Context context) {
        Uri returnUri = uri;
        Cursor returnCursor = context.getContentResolver().query(returnUri, null, null, null, null);

        // Get the column indexes of the data in the Cursor,
        // move to the first row in the Cursor, get the data,
        // and display it.

        int nameIndex = returnCursor.getColumnIndex(OpenableColumns.DISPLAY_NAME);
        int sizeIndex = returnCursor.getColumnIndex(OpenableColumns.SIZE);
        returnCursor.moveToFirst();
        String name = (returnCursor.getString(nameIndex));
        String size = (Long.toString(returnCursor.getLong(sizeIndex)));
        File file = new File(context.getFilesDir(), name);
        try {
            InputStream inputStream = context.getContentResolver().openInputStream(uri);
            FileOutputStream outputStream = new FileOutputStream(file);
            int read = 0;
            int maxBufferSize = 1 * 1024 * 1024;
            int bytesAvailable = inputStream.available();

            //int bufferSize = 1024;
            int bufferSize = Math.min(bytesAvailable, maxBufferSize);

            final byte[] buffers = new byte[bufferSize];
            while ((read = inputStream.read(buffers)) != -1) {
                outputStream.write(buffers, 0, read);
            }
            Log.e("File Size", "Size " + file.length());
            inputStream.close();
            outputStream.close();
            Log.e("File Path", "Path " + file.getPath());
            Log.e("File Size", "Size " + file.length());
        } catch (Exception e) {
            Log.e(LOG_TAG, e.getMessage());
        }
        return file.getPath();
    }


    private static String getDataColumn(Context context, Uri uri,
                                        String selection, String[] selectionArgs) {
        Cursor cursor = null;
        final String column = "_data";
        final String[] projection = {column};

        try {
            cursor = context.getContentResolver().query(uri, projection,
                    selection, selectionArgs, null);

            if (cursor != null && cursor.moveToFirst()) {
                final int index = cursor.getColumnIndexOrThrow(column);
                return cursor.getString(index);
            }
        } finally {
            if (cursor != null) {
                cursor.close();
            }
        }
        return null;
    }

    /**
     * @param uri - The Uri to check.
     * @return - Whether the Uri authority is ExternalStorageProvider.
     */
    private static boolean isExternalStorageDocument(Uri uri) {
        return "com.android.externalstorage.documents".equals(uri.getAuthority());
    }

    /**
     * @param uri - The Uri to check.
     * @return - Whether the Uri authority is DownloadsProvider.
     */
    private static boolean isDownloadsDocument(Uri uri) {
        return "com.android.providers.downloads.documents".equals(uri.getAuthority());
    }

    /**
     * @param uri - The Uri to check.
     * @return - Whether the Uri authority is MediaProvider.
     */
    private static boolean isMediaDocument(Uri uri) {
        return "com.android.providers.media.documents".equals(uri.getAuthority());
    }

    /**
     * @param uri - The Uri to check.
     * @return - Whether the Uri authority is Google Photos.
     */
    private static boolean isGooglePhotosUri(Uri uri) {
        return "com.google.android.apps.photos.content".equals(uri.getAuthority());
    }


    /**
     * @param uri The Uri to check.
     * @return Whether the Uri authority is Google Drive.
     */
    private static boolean isGoogleDriveUri(Uri uri) {
        return "com.google.android.apps.docs.storage".equals(uri.getAuthority()) //
                || "com.google.android.apps.docs.storage.legacy".equals(uri.getAuthority());
    }


}