Question

我正在尝试在android studio应用程序中导入一个sqlite数据库..我已经在我的设备内存中进行了备份...当我尝试在我的应用程序中导入数据库时，导致消息导入失败。请帮我导入我的db在我的应用程序中

我在文件夹中进行了备份：dbname.db

private void importDB() {
    try {
        File sd = Environment.getExternalStorageDirectory();
        File data = Environment.getDataDirectory();
        if (sd.canWrite()) {

            System.out.println("KKKKKKKKKKKKKKKKKKKKKK");
            String currentDBPath = "//data//" + getPackageName() + "//databases//" +"dbname.db" ;
            String backupDBPath = "Restore.db"; // From SD directory.

            System.out.println("HHHHHHHHHHHHHHHHHHHHHHH");
            File backupDB = new File(data, currentDBPath);
            File currentDB = new File(sd, backupDBPath);
            System.out.println("AAAAAAAAAAAAAAAAAAAAAAAAAaa");
            FileChannel src = new FileInputStream(backupDB).getChannel();
            FileChannel dst = new FileOutputStream(currentDB).getChannel();
            dst.transferFrom(src, 0, src.size());
            System.out.println("FFFFFFFFFFFFFFFFFFFFFFFFFFFFH");
            src.close();
            dst.close();
            Toast.makeText(getApplicationContext(), "Import Successful!",
                    Toast.LENGTH_SHORT).show();

        }
    } catch (Exception e) {

        Toast.makeText(getApplicationContext(), "Import Failed!", Toast.LENGTH_SHORT)
                .show();

    }
}

Answer 1

请按照以下步骤解决恢复SQlite DB

将file.db添加到project / assets文件夹中;

创建LinnaeusDatabase类：

  public class LinnaeusDatabase extends SQLiteOpenHelper {

  private static String DATABASE_NAME = "Dragonfly.db";
  public final static String DATABASE_PATH =
    "/data/data/com.kan.linnaeus/databases/";
 private static final int DATABASE_VERSION = 1;

 private SQLiteDatabase dataBase;
 private final Context dbContext;

public LinnaeusDatabase(Context context) {
super(context, DBActivity.DatabaseName, null, DATABASE_VERSION);
this.dbContext = context;
DATABASE_NAME = DBActivity.DatabaseName;
// checking database and open it if exists
if (checkDataBase()) {
    openDataBase();
} else {
    try {
        this.getReadableDatabase();
        copyDataBase();
        this.close();
        openDataBase();

    } catch (IOException e) {
        throw new Error("Error copying database");
    }
    Toast.makeText(context, "Initial database is created", Toast.LENGTH_LONG).show();
}
 }

private void copyDataBase() throws IOException {
InputStream myInput = dbContext.getAssets().open(DATABASE_NAME);
String outFileName = DATABASE_PATH + DATABASE_NAME;
OutputStream myOutput = new FileOutputStream(outFileName);

byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
    myOutput.write(buffer, 0, length);
}

myOutput.flush();
myOutput.close();
myInput.close();
}

  public void openDataBase() throws SQLException {
String dbPath = DATABASE_PATH + DATABASE_NAME;
dataBase = SQLiteDatabase.openDatabase(dbPath, null, SQLiteDatabase.OPEN_READWRITE);
}

 private boolean checkDataBase() {
SQLiteDatabase checkDB = null;
boolean exist = false;
try {
    String dbPath = DATABASE_PATH + DATABASE_NAME;
    checkDB = SQLiteDatabase.openDatabase(dbPath, null,
            SQLiteDatabase.OPEN_READONLY);
} catch (SQLiteException e) {
    Log.v("db log", "database does't exist");
}

if (checkDB != null) {
    exist = true;
    checkDB.close();
}
return exist;
 }
  }

如何导入sqlite db？

1 个答案: