假设您已将数据库下载到云端硬盘。
现在，我们如何在您的应用程序中获取它：
此示例包含带有 GUI 的 FragmentActivity。但是，您可以轻松地将其调整为静默下载。
@Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addApi(Drive.API)
.addScope(Drive.SCOPE_FILE)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.build();
mGoogleApiClient.connect();
}
@Override
protected void onActivityResult(final int requestCode, final int resultCode, final Intent data) {
switch (requestCode) {
case REQUEST_CODE_SUCCESS:
// Called after a file is saved to Drive.
if (resultCode == RESULT_OK) {
finish();
} else {
finish();
}
break;
case REQUEST_CODE_OPENER:
if (resultCode == RESULT_OK){
//Toast.makeText(this, R.string.pref_data_drive_import_success, Toast.LENGTH_LONG).show();
DriveId driveId = data.getParcelableExtra(
OpenFileActivityBuilder.EXTRA_RESPONSE_DRIVE_ID);
DriveFile file = driveId.asDriveFile();
processDriveFile(file);
} else {
Toast.makeText(this, R.string.pref_data_drive_import_error, Toast.LENGTH_LONG).show();
finish();
}
break;
}
}
@Override
public void onConnectionFailed(@NonNull ConnectionResult result) {
// Called whenever the API client fails to connect.
Log.i(TAG, "GoogleApiClient connection failed: " + result.toString());
if (!result.hasResolution()){
GoogleApiAvailability.getInstance().getErrorDialog(this, result.getErrorCode(), 0).show();
return;
}
try {
result.startResolutionForResult(this, REQUEST_CODE_RESOLUTION);
finish();
} catch (IntentSender.SendIntentException e){
Log.e(TAG, "Exception while starting resolution activity", e);
}
}
@Override
public void onConnected(Bundle connectionHint) {
Log.i(TAG, "API client connected.");
IntentSender intentSender = Drive.DriveApi
.newOpenFileActivityBuilder()
//.setMimeType(new String[] { "application/x-sqlite3" })
.build(mGoogleApiClient);
try {
startIntentSenderForResult(
intentSender, REQUEST_CODE_OPENER, null, 0, 0, 0);
} catch (IntentSender.SendIntentException e) {
Log.w(TAG, "Unable to send intent", e);
}
}
@Override
public void onConnectionSuspended(int cause) {
Log.i(TAG, "GoogleApiClient connection suspended");
}
现在，我们会检查所选文件是否是我们的数据库并替换它
private void processDriveFile(DriveFile file){
Log.i(TAG, "processDriveFile started");
file.open(mGoogleApiClient, DriveFile.MODE_READ_ONLY, null)
.setResultCallback(new ResultCallback<DriveApi.DriveContentsResult>() {
@Override
public void onResult(@NonNull DriveApi.DriveContentsResult driveContentsResult) {
if (!driveContentsResult.getStatus().isSuccess()){
Log.i(TAG, "Failed to create new contents.");
Toast.makeText(getApplicationContext(), "Import DB error", Toast.LENGTH_LONG).show();
finish();
return;
}
Log.i(TAG, "New contents created.");
DriveContents driveContents = driveContentsResult.getDriveContents();
InputStream inputStream = driveContents.getInputStream();
String dbDir = context.getDatabasePath("oldDbName.db").getParent();
String newFileName = "newDbName.db";
Log.i(TAG, "dbDir = " + dbDir);
// Deletion previous versions of new DB file from drive
File file = new File(dbDir + "/" + newFileName);
if (file.exists()){
Log.i(TAG, "newDbName.db EXISTS");
if (file.delete()){
Log.i(TAG, "newDbName.db DELETING old file....");
} else {
Log.i(TAG, "newDbName.db Something went wrong with deleting");
Toast.makeText(getApplicationContext(), "Import DB error", Toast.LENGTH_LONG).show();
finish();
}
}
try {
OutputStream output = new FileOutputStream(file);
try {
try {
byte[] buffer = new byte[4 * 1024]; // or other buffer size
int read;
while ((read = inputStream.read(buffer)) != -1) {
output.write(buffer, 0, read);
}
output.flush();
} finally {
output.close();
}
} catch (Exception e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(), "Import DB error", Toast.LENGTH_LONG).show();
finish();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(), "Import DB error", Toast.LENGTH_LONG).show();
finish();
} finally {
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(), "Import DB error", Toast.LENGTH_LONG).show();
finish();
}
}
// Check if file really match our DB
// Connection it to custom SqliteOpenHelper
ImportDBManager importDBManager = new ImportDBManager(context);
importDBManager.open();
// We have some System table in DB with 1 row in it for this goal
// So, we check if there is data in it
List<DataModelSystem> dataModelSystem = importDBManager.getSystemSingleRow(1);
importDBManager.close();
if (dataModelSystem.size() > 0){
Log.i(TAG, "DB MATCH!");
String mainDbName = context.getDatabasePath(DatabaseHelper.DB_NAME).toString();
String newDbName = context.getDatabasePath(ImportDatabaseHelper.DB_NAME).toString();
File oldDbFile = new File(mainDbName);
File newDbFile = new File(newDbName);
if (newDbFile.exists()){
Log.i(TAG, "newDbName.db EXISTS");
if (oldDbFile.delete()){
Log.i(TAG, "newDbName.db DELETING old file....");
try {
copyFile(newDbFile, oldDbFile);
Log.i(TAG, "success! New database");
Toast.makeText(getApplicationContext(), "Import OK!!!!1", Toast.LENGTH_LONG).show();
} catch (IOException e) {
Toast.makeText(getApplicationContext(), "Import DB error", Toast.LENGTH_LONG).show();
Log.i(TAG, "fail! old database will remain");
e.printStackTrace();
finish();
}
} else {
Log.i(TAG, "newDbName.db Something went wrong with deleting");
Toast.makeText(getApplicationContext(), "Import DB error", Toast.LENGTH_LONG).show();
finish();
}
}
} else {
Log.i(TAG, "db not Match!");
Toast.makeText(getApplicationContext(),"Import DB error", Toast.LENGTH_LONG).show();
finish();
}
}
});
finish();
}
// Replacing old file
private static void copyFile(File src, File dst) throws IOException {
Log.i(TAG, "src = " + src.getAbsolutePath());
Log.i(TAG, "dst = " + dst.getAbsolutePath());
FileInputStream var2 = new FileInputStream(src);
FileOutputStream var3 = new FileOutputStream(dst);
byte[] var4 = new byte[1024];
int var5;
while((var5 = var2.read(var4)) > 0) {
var3.write(var4, 0, var5);
}
var2.close();
var3.close();
}
100% 正常工作