我的应用程序一运行，就会实现一个管理数据库版本的SQLiteOpenHelper对象。
如果数据库不存在或已过时，我们会将其从assets文件夹复制到Android设备。
问题是，当我尝试查询数据库时，我收到以下错误。
08-26 14:56:21.712: V/Database Milestone(2403): The Database has been successfully copied.
08-26 14:56:21.722: V/Databae Log Statement(2403): The onUpgrade method of the DataBaseHelper has been called.
08-26 14:56:21.892: E/SQLiteLog(2403): (1) no such table: CARDS
08-26 14:56:21.942: W/System.err(2403): android.database.sqlite.SQLiteException: no such table: CARDS (code 1): , while compiling: Select DISTINCT _id, Name FROM CARDS LEFT JOIN `CARD-EFFECT` USING (_ID)
08-26 14:56:22.022: W/System.err(2403): at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
08-26 14:56:22.042: W/System.err(2403): at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
08-26 14:56:22.082: W/System.err(2403): at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
08-26 14:56:22.082: W/System.err(2403): at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
08-26 14:56:22.092: W/System.err(2403): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
08-26 14:56:22.092: W/System.err(2403): at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
08-26 14:56:22.092: W/System.err(2403): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
08-26 14:56:22.092: W/System.err(2403): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1314)
08-26 14:56:22.142: W/System.err(2403): at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1253)
08-26 14:56:22.152: W/System.err(2403): at com.example.mycursoradapter.CardListView.onActivityCreated(CardListView.java:92)
这是我用来管理数据库的SQLiteOpenHelper类。
public class DataBaseHelper extends SQLiteOpenHelper
{
//The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.example.mycursoradapter/databases/";
private static String DB_NAME = "hearthstonedata";
private final Context myContext;
private final static int LASTEST_DATABASE_VERSION = 15;
public DataBaseHelper(Context context)
{
super(context, DB_NAME, null, LASTEST_DATABASE_VERSION);
this.myContext = context;
}
/**
* Copies your database from your local assets-folder to the just created
* empty database in the system folder, from where it can be accessed and
* handled. This is done by transfering bytestream.
* */
public void copyDataBase() throws IOException
{
// Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
// Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
// transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
// Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
Log.v("Database Milestone", "The Database has been successfully copied.");
}
@Override
public void onCreate(SQLiteDatabase arg0)
{
Log.v("Pierre D Log Statement", "The database has not been copied yet.");
try
{
this.copyDataBase();
}
catch (IOException e)
{
e.printStackTrace();
}
Log.v("Pierre D Log Statement", "The onCreate method of the DataBaseHelper has been called.");
}
@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2)
{
try
{
Log.v("Pierre db OnUpgrade", String.valueOf(arg0.isOpen()));
this.copyDataBase();
}
catch (IOException e)
{
e.printStackTrace();
}
Log.v("Pierre D Log Statement", "The onUpgrade method of the DataBaseHelper has been called.");
}
}
这是我查询数据库的地方。
public class CardListView extends Fragment
{
private final String SQL_BASE_QUERY = "Select DISTINCT _id, Name FROM CARDS LEFT JOIN `CARD-EFFECT` USING (_ID)";
private Activity currentActivity;
private DataBaseHelper myDbHelper;
public static SQLiteDatabase database;
private Cursor mainCursor;
public CardListView()
{
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
// Inflate the layout for this fragment
return inflater.inflate(R.layout.list_view, container, false);
}
public void onActivityCreated(Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
currentActivity = this.getActivity();
myDbHelper = new DataBaseHelper(currentActivity);
database = myDbHelper.getReadableDatabase();
Log.v("Testing the Which value", "Database size in bytes " + String.valueOf(database.getPageSize()));
Log.v("Testing the Which value", "Database path " + String.valueOf(database.getPath()));
Log.v("Testing the Which value", "Database version number " + String.valueOf(database.getVersion()));
// I am getting the error at this line
mainCursor = database.rawQuery(SQL_BASE_QUERY, null);
我知道我的查询正在运行，因为我已经在SQLite程序上测试了它。我知道桌子卡片退出了。这只是创建/复制和打开数据库的问题。
答案 0 :(得分：1)
您是否尝试卸载应用程序并重新安装它，这将删除现有数据库，否则它将不会从其资产资源中复制数据库。它将使用先前存在的数据库。
答案 1 :(得分：0)
您的数据库输出已成功复制＆＃39;无论如何打印。即使数据库没有被复制。所以你不知道数据库是否真的被复制了。问题必须出在副本上，因为表示表格不存在
尝试使用从文件夹导入数据库的那个：
importDb.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
importDB();
}
});
// importing database
@SuppressLint("SdCardPath")
private void importDB() {
try {
// File file = getBaseContext().getFileStreamPath(Environment.getExternalStorageDirectory()
// + "/MyDatabase");
// if(file.exists()){
FileInputStream fis = new FileInputStream(Environment.getExternalStorageDirectory()
+ "/MyDatabase");
String outFileName = "/data/data/com.example.mycarfuel/databases/MyDatabase";
OutputStream output = new FileOutputStream(outFileName);
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(SettingsActivity.this, "Database loaded succesfully",
Toast.LENGTH_LONG).show();
//}else{
//Toast.makeText(SettingsActivity.this, "File does not exist in 'mnt/sdcard/' location. Please add the 'MyDatabase' file here in order to import",
// Toast.LENGTH_LONG).show();
//}
} catch (Exception e) {
Toast.makeText(getBaseContext(), e.toString(), Toast.LENGTH_LONG)
.show();
}
}