我正在制作一个将其SQLite数据库备份存储在GDrive上的应用程序。我成功登录并上传了驱动器中的文件，但无法还原它。以下是代码。我使用SQLiteDatabase来存储fileID，以便在更新和还原时需要它时可以使用它。我正在寻找一种将使用FileID进行还原的方法。在file.getDownloadUrl（）和file.getContent（）处发生错误。
class DriveClassHelper
{
private final Executor mExecutor = Executors.newSingleThreadExecutor();
private static Drive mDriveService;
private String FileID = null;
private static String filePath = "/data/data/com.example.gdrivebackup/databases/Data.db";
DriveClassHelper(Drive mDriveService)
{
DriveClassHelper.mDriveService = mDriveService;
}
// ---------------------------------- TO BackUp on Drive -------------------------------------------
public Task<String> createFile()
{
return Tasks.call(mExecutor, () ->
{
File fileMetaData = new File();
fileMetaData.setName("Backup");
java.io.File file = new java.io.File(filePath);
String mimeType = MimeTypeMap.getSingleton().getExtensionFromMimeType("application/x-sqlite-3");
FileContent mediaContent = new FileContent(mimeType, file);
File myFile = null;
FileID = getFileIDFromDatabase();
try {
if (FileID != null) {
Log.i("CALLED : ", FileID);
//mDriveService.files().delete().execute();
myFile = mDriveService.files().update(FileID, fileMetaData, mediaContent).execute();
} else {
myFile = mDriveService.files().create(fileMetaData, mediaContent).execute();
MainActivity.demoSQLite.insertData(myFile.getId());
}
} catch (Exception e) {
e.printStackTrace();
}
if (myFile == null) {
throw new IOException("Null Result when requesting file creation");
}
Log.i("ID:", myFile.getId());
return myFile.getId();
}
);
}
// -------------------------------------------------------------------------------------------------
// ---------------------------------- TO get File ID -------------------------------------------
private static String getFileIDFromDatabase()
{
String FileIDFromMethod = null;
Cursor result = MainActivity.demoSQLite.getData();
if (result.getCount() == 0) {
Log.i("CURSOR :", "NO ENTRY");
return null;
} else {
while (result.moveToNext()) {
FileIDFromMethod = result.getString(0);
}
return FileIDFromMethod;
}
}
// -------------------------------------------------------------------------------------------------
// ---------------------------------- TO Restore -------------------------------------------
public static class Restore extends AsyncTask<Void, Void, String>
{
@Override
protected String doInBackground(Void... params) {
String fileId = null;
try
{
fileId = getFileIDFromDatabase();
if (fileId != null)
{
File file = mDriveService.files().get(fileId).execute();
downloadFile(file);
}
else
{
return null;
}
}
catch (Exception e)
{
e.printStackTrace();
}
return fileId;
}
private void downloadFile(File file)
{
InputStream mInput = null;
FileOutputStream mOutput = null;
if (file.getDownloadUrl() != null && file.getDownloadUrl().length() > 0) //Error occurs at file.getDownloadUrl()
{
try
{
HttpResponse resp = mDriveService.getRequestFactory().buildGetRequest(new GenericUrl(file.getDownloadUrl())).execute();
mInput = resp.getContent();
String outFileName = "file://" + Environment.getDataDirectory().getPath() + filePath;
// Log.e("com.example.myapp", "getDatabasePath="+ getDatabasePath(""));
//Log.e("com.example.myapp", "outFileName="+outFileName);
// String outFileName = "../databases/" + "Quickpay.db";
mOutput = new FileOutputStream(outFileName);
byte[] mBuffer = new byte[1024];
int mLength;
while ((mLength = mInput.read(mBuffer)) > 0)
{
mOutput.write(mBuffer, 0, mLength);
}
mOutput.flush();
}
catch (IOException e)
{
// An error occurred.
e.printStackTrace();
// return null;
}
finally
{
try
{
//Close the streams
if (mOutput != null)
{
mOutput.close();
}
if (mInput != null)
{
mInput.close();
}
}
catch (IOException e)
{
Log.e("com.example.myapp", "failed to close databases");
}
}
}
else
{
// The file doesn't have any content stored on Drive.
// return null;
Log.e("com.example.myapp", "No content on Drive");
}
}
}
}
Gradle文件类似
implementation 'com.google.android.gms:play-services-auth:16.0.1'
implementation('com.google.apis:google-api-services-drive:v3-rev136-1.25.0')
{
exclude group: 'org.apache.httpcomponents'
}
implementation('com.google.api-client:google-api-client-android:1.26.0')
{
exclude group: 'org.apache.httpcomponents'
}
implementation 'com.google.http-client:google-http-client-gson:1.26.0'
据我所知，下载URL仅在Google驱动器api v2中可用，而在V3中不可用。
文件的短期下载URL。仅针对包含存储在Google云端硬盘中的内容的文件填充此字段；没有为Google文档或快捷方式文件填充它。
我认为这不是很稳定，因为并非所有文件类型都会返回下载网址。
使用Google云端硬盘v3，您应该使用流下载文件。
String fileId = "0BwwA4oUTeiV1UVNwOHItT0xfa2M";
OutputStream outputStream = new ByteArrayOutputStream();
driveService.files().get(fileId)
.executeMediaAndDownloadTo(outputStream);
这应该与还原一起使用。让我知道是否可以，因为我尝试恢复，所以已经有一段时间了。