大家好今天繼續示範文件上傳至雲端的功能。
我們先新增一個名為FileUtil的Java Class:

import android.provider.MediaStore;
import android.text.TextUtils;

import androidx.annotation.NonNull;

import java.io.File;
import java.util.Locale;

public class FileUtil {
    /**
 * 根据Uri獲取檔案路徑
 * @param context context
 * @param uri     uri
 */
public static String getFileAbsolutePath(Context context, Uri uri) {
    if (context == null || uri == null) return null;
    // DocumentProvider
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT && DocumentsContract.isDocumentUri(context, uri)) {
        if (isExternalStorageDocument(uri)) {
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            final String type = split[0];
            if ("primary".equalsIgnoreCase(type)) {
                return Environment.getExternalStorageDirectory() + "/" + split[1];
            }else if ("home".equalsIgnoreCase(type)) {
                return Environment.getExternalStorageDirectory() + "/documents/" + split[1];
            }
        } else if (isDownloadsDocument(uri)) {
            // DownloadsProvider
            final String id = DocumentsContract.getDocumentId(uri);
            if (TextUtils.isEmpty(id)) {
                return null;
            }
            if (id.startsWith("raw:")) {
                return id.substring(4);
            }
            String[] contentUriPrefixesToTry = new String[]{
                    "content://downloads/public_downloads",
                    "content://downloads/my_downloads",
                    "content://downloads/all_downloads"
            };
            for (String contentUriPrefix : contentUriPrefixesToTry) {
                try {
                    Uri contentUri = ContentUris.withAppendedId(Uri.parse(contentUriPrefix), Long.valueOf(id));
                    String path = getDataColumn(context, contentUri, null, null);
                    if (path != null) {
                        return path;
                    }
                } catch (Exception ignore) {
                }
            }
            try {
                String path = getDataColumn(context, uri, null, null);
                if (path != null) {
                    return path;
                }
            } catch (Exception ignore) {
            }
            // path could not be retrieved using ContentResolver, therefore copy file to accessible cache using streams
            return null;
        } else if (isMediaDocument(uri)) {
            // MediaProvider
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            final String type = split[0];

            Uri contentUri;
            switch (type.toLowerCase(Locale.ENGLISH)) {
                case "image":
                    contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
                    break;
                case "video":
                    contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
                    break;
                case "audio":
                    contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
                    break;
                default:
                    contentUri = MediaStore.Files.getContentUri("external");
                    break;
            }
            final String selection = MediaStore.MediaColumns._ID +"=?";
            final String[] selectionArgs = new String[]{split[1]};
            return getDataColumn(context, contentUri, selection, selectionArgs);
        }
    } else if (ContentResolver.SCHEME_CONTENT.equalsIgnoreCase(uri.getScheme())) {
        // MediaStore (and general)
        // Return the remote address
        if (isGooglePhotosUri(uri)) {
            return uri.getLastPathSegment();
        }
        return getDataColumn(context, uri, null, null);
    } else if (ContentResolver.SCHEME_FILE.equalsIgnoreCase(uri.getScheme())) {
        // File
        return uri.getPath();
    }
    return null;
}
    public static String getDataColumn(Context context, @NonNull Uri uri, String selection, String[] selectionArgs) {
        Cursor cursor = null;
        String column = MediaStore.Images.Media.DATA;
        String[] projection = {column};
        try {
            cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null);
            if (cursor != null && cursor.moveToFirst()) {
                int index = cursor.getColumnIndexOrThrow(column);
                return cursor.getString(index);
            }
        } catch (Exception ignore) {
        } finally {
            if (cursor != null)
                cursor.close();
        }
        return null;
    }

    //檔案名
    public static String fileName(String path){
        if( path == null || path.isEmpty() ) return "";

        File file = new File(path);

        if( !file.exists() || !file.isFile() ) {
            return "";
        }

        String filename = file.getName();

//        String ext      = FileKit.getFileExt(filename);
//        if( !ext.equalsIgnoreCase(".csv") ){
//            return "";
//        }

        return filename;
    }

    public static boolean isExternalStorageDocument(Uri uri) {
        return "com.android.externalstorage.documents".equals(uri.getAuthority());
    }

    public static boolean isDownloadsDocument(Uri uri) {
        return "com.android.providers.downloads.documents".equals(uri.getAuthority());
    }

    public static boolean isMediaDocument(Uri uri) {
        return "com.android.providers.media.documents".equals(uri.getAuthority());
    }

    public static boolean isGooglePhotosUri(Uri uri) {
        return "com.google.android.apps.photos.content".equals(uri.getAuthority());
    }
    }

這一個class的功用是將選擇檔案的路徑由Uri轉為String和拿到檔案的名字，各位也可以去網路上搜尋其他的方法。

接下來我們再新增另一個Java Class
GoogleDriveServiceFunction:

public class GoogleDriveServiceFunction {
    private final Executor mExecutor = Executors.newSingleThreadExecutor();

    Drive mDriveService;

    public GoogleDriveServiceFunction(Drive mDriveService) {
        this.mDriveService = mDriveService;
    }

   public Task<String> createFile(String filePath, String fileName){
        return Tasks.call(mExecutor,() ->{
            Log.e("file", filePath+","+fileName );

            File fileMetaData = new File();
            fileMetaData.setName(fileName);

            java.io.File file = new java.io.File(filePath);

            FileContent mediaContent = new FileContent("application/octet-stream",file);

            File myFile = null;
            try{
                myFile = mDriveService.files().create(fileMetaData,mediaContent)
                        .execute();

                Log.e("File" ,"Flie ID = " +myFile.getId());
            }catch (Exception e){
                e.printStackTrace();
            }

            if (myFile == null){
                throw new IOException("Null result when request file creation");
            }

            return myFile.getId();
        });
    }

    public Task<String> createFolder(){
        return Tasks.call(mExecutor,() ->{
            File fileMetaData = new File();
            fileMetaData.setName("Test1");
            fileMetaData.setMimeType("application/vnd.google-apps.folder");

            File folder = mDriveService.files().create(fileMetaData)
                    .setFields("id")
                    .execute();

            Log.e("folderid", "createFolder: " + folder.getId() );
            return folder.getId();
        });
    }
    
    public Task<String> searchFile(){
        return Tasks.call(mExecutor,() ->{
            String pageToken = null;

            try{
                do {
                    FileList reset =mDriveService.files().list()
                            .setQ("'xxxxxxxxxx@gmail.com' in writers")
                            .setSpaces("drive")
                            .setFields("nextPageToken, files(id,name,mimeType)")
                            .setPageToken(pageToken)
                            .execute();
                    for (File file : reset.getFiles()){
                        Log.e("File", "File: "+file.getName()+","+file.getId()+","+file.getMimeType());
                    }
                    pageToken = reset.getNextPageToken();
                }while (pageToken !=null);


            }catch (UserRecoverableAuthIOException e) {
                e.printStackTrace();
                Log.e("err",e.getMessage());

            } catch (IOException e) {
                e.printStackTrace();
                Log.e("err",e.getMessage());

            }
            return null;
        });
    }
  }

createFile程式碼的FileContent mediaContent = new FileContent("application/octet-stream",file);是指上傳檔案的格式是二進制檔案。

createFolder程式碼的fileMetaData.setMimeType("application/vnd.google-apps.folder");這一行是在雲端硬碟的資料夾的mimeType格式。

searchFile程式碼得setQ可以設定搜尋的條件，我們可以由下面的網址去設定我們要使用的條件。

https://developers.google.com/drive/api/v3/search-files

在MainActivity加上以下的程式碼:

 private static final int PICK_IMAGE_FROM_GALLERY_REQUEST_CODE = 300;
 private Button btnChooseFile;
 private Button btnSearchGD;
 private Button btnCreateFolder;

在MainActivity的onCreate加上:

protected void onCreate(Bundle savedInstanceState) {
        ...
        init();
    }

private void init(){
        btnChooseFile = findViewById(R.id.btnChooseFile);
        btnCreateFolder = findViewById(R.id.btnCreateFolder);
        btnSearchGD = findViewById(R.id.btnSearchGoogledrive);
        btnChooseFile.setOnClickListener(this);
        btnCreateFolder.setOnClickListener(this);
        btnSearchGD.setOnClickListener(this);
    }

 @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.btnChooseFile:
                chooseFile();
                break;
            case R.id.btnCreateFolder:
                createFolder();
                break;
            case R.id.btnSearchGoogledrive:
                searchGoogleDrive();
                break;
        }
    }

    private void searchGoogleDrive() {
        googleDriveServiceFunction.searchFile();
    }

    private void createFolder() {
        googleDriveServiceFunction.createFolder();
    }

    public void chooseFile(){
        //Create an Intent with action as ACTION_GET_CONTENT
        Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
        //設定選擇的檔案格式
        intent.setType("image/*");
        //檔案複選True
        intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);

        //We pass an extra array with the accepted mime types. This will ensure only components with these MIME types as targeted.
        String[] mimeTypes = {"image/jpeg", "image/png"};
        intent.putExtra(Intent.EXTRA_MIME_TYPES, mimeTypes);
        // Launching the Intent
        startActivityForResult(intent, PICK_IMAGE_FROM_GALLERY_REQUEST_CODE);

    }

上面intent.setType的功能是設定選擇的檔案格式，可以是圖片、影片、或是csv文件等等，我們可以藉由https://www.jianshu.com/p/c1656748849f
這個網址去尋找文件的mimeType。
intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true)是設定檔案是否可以複選，我們這邊先示範用圖片去上傳檔案。

在onActivityResult裡面加上:

  @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
       ...

        if (requestCode == PICK_IMAGE_FROM_GALLERY_REQUEST_CODE && resultCode == RESULT_OK) {
            ArrayList<String> uriList = new ArrayList<String>();

            if (data.getClipData() != null) {
                for (int i = 0; i < data.getClipData().getItemCount(); i++) {
                    uriList.add(FileUtil.getFileAbsolutePath(this,data.getClipData().getItemAt(i).getUri()));
                    Log.e("FilePath", "" + uriList.get(i));
                }
            } else if (Build.VERSION.SDK_INT >= 16 && data.getClipData() == null) {
                uriList.add(FileUtil.getFileAbsolutePath(this,data.getData()));
                Log.e("FilePath", "" + uriList.get(0));
            }
            //照片的uri
            uploadFile(uriList);
        }
    }

public void uploadFile(ArrayList<String> uriList){
        ArrayList<Uri> uris = null;
        for (int i=0;i<uriList.size();i++){
            Log.e("eee",""+uriList.get(i));
            googleDriveServiceFunction.createFile(uriList.get(i),FileUtil.fileName(uriList.get(i)))
                    .addOnSuccessListener(new OnSuccessListener<String>() {
                        @Override
                        public void onSuccess(String s) {
                            Toast.makeText(getApplicationContext(), "Uploaded successfully", Toast.LENGTH_LONG).show();
                        }
                    }).addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                    Toast.makeText(getApplicationContext(), "Check your google api key", Toast.LENGTH_LONG).show();
                    Log.e("error",e.getMessage());
                }
            });
        }
    }

如果版本是android Q 的話，我們要在AndroidManifest.xml的application裡面加上

android:requestLegacyExternalStorage="true"

否則會上傳失敗。
這樣一來，上傳檔案至雲端硬碟就告一段落了。