我有五個 sqlite 數據庫，我希望用戶能夠在手機中進行本地備份，并且可以恢復備份文件。我不知道如何創建這些備份并以編程方式恢復它們。我使用了 github 存儲庫，但它根本不起作用，我需要你的幫助來創建這個備份和恢復過程。感謝您的關注
2 回答
慕桂英4014372
TA貢獻1871條經驗 獲得超13個贊
在您的活動中制作備份和恢復按鈕并定義本地數據庫變量，例如，
private MainDatabase localBackup = new MainDatabase(this);
然后點擊即可進行備份和恢復操作
@Override
public void onClick(View v) {
final MainDatabase db = new MainDatabase(getApplicationContext());
switch (v.getId()) {
case R.id.tvBackUp:
String outFileName = Environment.getExternalStorageDirectory() +
File.separator + getResources().getString(R.string.app_name) + File.separator;
localBackup.performBackup(db, outFileName);
break;
case R.id.tvRestore:
File folder = new File(Environment.getExternalStorageDirectory() + File.separator + getApplicationContext().getResources().getString(R.string.app_name));
if (folder.exists()) {
final File[] files = folder.listFiles();
if (files.length == 0) {
Toast.makeText(this, "No any Backup", Toast.LENGTH_SHORT).show();
} else {
localBackup.performRestore(db);
}
}
break;
}
}
在數據庫文件中制定備份方法
public void performBackup(final MainDatabase db, final String outFileName) {
File folder = new File(Environment.getExternalStorageDirectory() + File.separator
+ mContext.getResources().getString(R.string.app_name));
boolean success = true;
if (!folder.exists())
success = folder.mkdirs();
if (success) {
final Dialog dialog = new Dialog(mContext);
dialog.setContentView(R.layout.backup_dialog);
dialog.getWindow().getAttributes().windowAnimations =
R.style.PauseDialogAnimation;
dialog.getWindow().setBackgroundDrawableResource(android.R.color.transparent);
dialog.show();
Button btnSave = dialog.findViewById(R.id.btnSave);
Button btnCancel = dialog.findViewById(R.id.btnCancel);
EditText etName = dialog.findViewById(R.id.etName);
etName.setInputType(InputType.TYPE_CLASS_TEXT);
btnSave.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String m_Text = etName.getText().toString();
String out = outFileName + m_Text + ".db";
db.backup(out);
dialog.dismiss();
}
});
btnCancel.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
dialog.dismiss();
}
});
} else
Toast.makeText(mContext, "Unable to create directory. Retry",
Toast.LENGTH_SHORT).show();
}
public void backup(String outFileName) {
//database path
final String inFileName = mContext.getDatabasePath(DATABASE_NAME).toString();
try {
File dbFile = new File(inFileName);
FileInputStream fis = new FileInputStream(dbFile);
// Open the empty db as the output stream
OutputStream output = new FileOutputStream(outFileName);
// Transfer bytes from the input file to the output file
byte[] buffer = new byte[1024];
int length;
while ((length = fis.read(buffer)) > 0) {
output.write(buffer, 0, length);
}
// Close the streams
output.flush();
output.close();
fis.close();
Toast.makeText(mContext, "Backup Completed", Toast.LENGTH_SHORT).show();
} catch (Exception e) {
Toast.makeText(mContext, "Unable to backup database. Retry",
Toast.LENGTH_SHORT).show();
e.printStackTrace();
}
}
以及進行恢復時，詢問用戶要恢復什么備份
public void performRestore(final MainDatabase db) {
File folder = new File(Environment.getExternalStorageDirectory() + File.separator
+ mContext.getResources().getString(R.string.app_name));
if (folder.exists()) {
final File[] files = folder.listFiles();
final ArrayAdapter<String> arrayAdapter = new ArrayAdapter<>(mContext,
android.R.layout.select_dialog_item);
for (File file : files)
arrayAdapter.add(file.getName());
AlertDialog.Builder builderSingle = new AlertDialog.Builder(mContext);
builderSingle.setTitle("Select & Restore ");
builderSingle.setNegativeButton("cancle", (dialog, which) ->
dialog.dismiss());
builderSingle.setAdapter(arrayAdapter, (dialog, which) -> {
try {
db.importDB(files[which].getPath());
} catch (Exception e) {
Toast.makeText(mContext, "Unable to restore. Retry",
Toast.LENGTH_SHORT).show();
}
});
builderSingle.show();
} else
Toast.makeText(mContext, "Backup folder not present.\nDo a backup before a
restore!", Toast.LENGTH_SHORT).show();
}
public void importDB(String inFileName) {
final String outFileName = mContext.getDatabasePath(DATABASE_NAME).toString();
try {
File dbFile = new File(inFileName);
FileInputStream fis = new FileInputStream(dbFile);
// Open the empty db as the output stream
OutputStream output = new FileOutputStream(outFileName);
// Transfer bytes from the input file to the output file
byte[] buffer = new byte[1024];
int length;
while ((length = fis.read(buffer)) > 0) {
output.write(buffer, 0, length);
}
// Close the streams
output.flush();
output.close();
fis.close();
Toast.makeText(mContext, "Restore Completed", Toast.LENGTH_SHORT).show();
} catch (Exception e) {
Toast.makeText(mContext, "Unable to import database. Retry",
Toast.LENGTH_SHORT).show();
e.printStackTrace();
}
}
拉莫斯之舞
TA貢獻1820條經驗 獲得超10個贊
如果您的清單中有的話，Android 已經支持系統自動備份android:allowBackup="true"。如果這還不夠，并且您想在應用程序重新安裝之間手動管理備份，那么您必須將數據庫從context.getDatabasePath("<your-database-name>")外部存儲復制到某個地方，然后在需要時將其復制回來
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