Android 在设备上运行时没有这样的表错误,但在模拟器上运行时,相同的代码可以正常工作
我有一个非常奇怪的问题,我正在编写一个代码,从数据库中获取数据并在listView中显示,所以我创建了一个类来获取数据库,另一个类用于适配器。 但当我在设备上运行它时,我并没有得到这样的表错误,尽管它在emulator上运行良好。另外,我在同一个项目中的另一个数据库中尝试了这段代码,它正在工作。我将android_元数据表添加到它们中,但仍然不起作用 这是我的Android 在设备上运行时没有这样的表错误,但在模拟器上运行时,相同的代码可以正常工作,android,sqlite,Android,Sqlite,我有一个非常奇怪的问题,我正在编写一个代码,从数据库中获取数据并在listView中显示,所以我创建了一个类来获取数据库,另一个类用于适配器。 但当我在设备上运行它时,我并没有得到这样的表错误,尽管它在emulator上运行良好。另外,我在同一个项目中的另一个数据库中尝试了这段代码,它正在工作。我将android_元数据表添加到它们中,但仍然不起作用 这是我的db类 public class Directory_DB extends SQLiteOpenHelper{ private stat
db类
public class Directory_DB extends SQLiteOpenHelper{
private static String TAG = "DataBaseHelper"; // Tag just for the LogCat window
//destination path (location) of our database on device
private static String DB_PATH = "";
private static String DB_NAME ;// Database name
private SQLiteDatabase mDataBase;
private final Context mContext;
private String TABLE_NAME;
public Directory_DB(Context context , String DB_NAME )
{
super(context , DB_NAME, null , 2);// 1? its Database Version
DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
this.mContext = context;
this.DB_NAME = DB_NAME;
}
public void createDataBase() throws IOException
{
//If database not exists copy it from the assets
boolean mDataBaseExist = checkDataBase();
if(!mDataBaseExist)
{
this.getReadableDatabase();
this.close();
try
{
//Copy the database from assests
copyDataBase();
Log.e(TAG, "createDatabase database created");
}
catch (IOException mIOException)
{
throw new Error("ErrorCopyingDataBase");
}
}
}
//Check that the database exists here: /data/data/your package/databases/Da Name
private boolean checkDataBase()
{
File dbFile = new File(DB_PATH + DB_NAME);
Log.v("dbFile", dbFile + " "+ dbFile.exists());
return dbFile.exists();
}
//Copy the database from assets
private void copyDataBase() throws IOException
{
InputStream mInput = mContext.getAssets().open(DB_NAME);
String outFileName = DB_PATH + DB_NAME;
OutputStream mOutput = new FileOutputStream(outFileName);
byte[] mBuffer = new byte[1024];
int mLength;
while ((mLength = mInput.read(mBuffer))>0)
{
mOutput.write(mBuffer, 0, mLength);
}
mOutput.flush();
mOutput.close();
mInput.close();
}
//Open the database, so we can query it
public boolean openDataBase() throws SQLException
{
String mPath = DB_PATH + DB_NAME;
//Log.v("mPath", mPath);
mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.CREATE_IF_NECESSARY);
//mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS);
return mDataBase != null;
}
@Override
public synchronized void close()
{
if(mDataBase != null)
mDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
public class DirectoryAdapter {
public static final String TAG_ID = "_id";
public static String TAG_TABLE_NAME;
protected static final String TAG = "DataAdapter";
private final Context mContext;
private SQLiteDatabase mDb;
private Directory_DB mDbHelper;
public DirectoryAdapter(Context context, String DB_NAME, String TABLE_NAME) {
this.mContext = context;
mDbHelper = new Directory_DB(mContext, DB_NAME );
this.TAG_TABLE_NAME = TABLE_NAME;
Log.d("Database name in adapter", DB_NAME);
Log.d("Table name in adapter", TAG_TABLE_NAME);
}
public DirectoryAdapter createDatabase() throws SQLException {
try {
mDbHelper.createDataBase();
} catch (IOException mIOException) {
Log.e(TAG, mIOException.toString() + " UnableToCreateDatabase");
throw new Error("UnableToCreateDatabase");
}
return this;
}
public DirectoryAdapter open() throws SQLException {
try {
mDbHelper.openDataBase();
mDbHelper.close();
mDb = mDbHelper.getReadableDatabase();
} catch (SQLException mSQLException) {
Log.e(TAG, "open >>" + mSQLException.toString());
throw mSQLException;
}
return this;
}
public void close() {
mDbHelper.close();
}
public Cursor getTestData() {
try {
String sql = "SELECT * FROM " + TAG_TABLE_NAME;
Cursor mCur = mDb.rawQuery(sql, null);
return mCur;
} catch (SQLException mSQLException) {
Log.e(TAG, "getTestData >>" + mSQLException.toString());
throw mSQLException;
}
}
}
这是我的适配器类
public class Directory_DB extends SQLiteOpenHelper{
private static String TAG = "DataBaseHelper"; // Tag just for the LogCat window
//destination path (location) of our database on device
private static String DB_PATH = "";
private static String DB_NAME ;// Database name
private SQLiteDatabase mDataBase;
private final Context mContext;
private String TABLE_NAME;
public Directory_DB(Context context , String DB_NAME )
{
super(context , DB_NAME, null , 2);// 1? its Database Version
DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
this.mContext = context;
this.DB_NAME = DB_NAME;
}
public void createDataBase() throws IOException
{
//If database not exists copy it from the assets
boolean mDataBaseExist = checkDataBase();
if(!mDataBaseExist)
{
this.getReadableDatabase();
this.close();
try
{
//Copy the database from assests
copyDataBase();
Log.e(TAG, "createDatabase database created");
}
catch (IOException mIOException)
{
throw new Error("ErrorCopyingDataBase");
}
}
}
//Check that the database exists here: /data/data/your package/databases/Da Name
private boolean checkDataBase()
{
File dbFile = new File(DB_PATH + DB_NAME);
Log.v("dbFile", dbFile + " "+ dbFile.exists());
return dbFile.exists();
}
//Copy the database from assets
private void copyDataBase() throws IOException
{
InputStream mInput = mContext.getAssets().open(DB_NAME);
String outFileName = DB_PATH + DB_NAME;
OutputStream mOutput = new FileOutputStream(outFileName);
byte[] mBuffer = new byte[1024];
int mLength;
while ((mLength = mInput.read(mBuffer))>0)
{
mOutput.write(mBuffer, 0, mLength);
}
mOutput.flush();
mOutput.close();
mInput.close();
}
//Open the database, so we can query it
public boolean openDataBase() throws SQLException
{
String mPath = DB_PATH + DB_NAME;
//Log.v("mPath", mPath);
mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.CREATE_IF_NECESSARY);
//mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS);
return mDataBase != null;
}
@Override
public synchronized void close()
{
if(mDataBase != null)
mDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
public class DirectoryAdapter {
public static final String TAG_ID = "_id";
public static String TAG_TABLE_NAME;
protected static final String TAG = "DataAdapter";
private final Context mContext;
private SQLiteDatabase mDb;
private Directory_DB mDbHelper;
public DirectoryAdapter(Context context, String DB_NAME, String TABLE_NAME) {
this.mContext = context;
mDbHelper = new Directory_DB(mContext, DB_NAME );
this.TAG_TABLE_NAME = TABLE_NAME;
Log.d("Database name in adapter", DB_NAME);
Log.d("Table name in adapter", TAG_TABLE_NAME);
}
public DirectoryAdapter createDatabase() throws SQLException {
try {
mDbHelper.createDataBase();
} catch (IOException mIOException) {
Log.e(TAG, mIOException.toString() + " UnableToCreateDatabase");
throw new Error("UnableToCreateDatabase");
}
return this;
}
public DirectoryAdapter open() throws SQLException {
try {
mDbHelper.openDataBase();
mDbHelper.close();
mDb = mDbHelper.getReadableDatabase();
} catch (SQLException mSQLException) {
Log.e(TAG, "open >>" + mSQLException.toString());
throw mSQLException;
}
return this;
}
public void close() {
mDbHelper.close();
}
public Cursor getTestData() {
try {
String sql = "SELECT * FROM " + TAG_TABLE_NAME;
Cursor mCur = mDb.rawQuery(sql, null);
return mCur;
} catch (SQLException mSQLException) {
Log.e(TAG, "getTestData >>" + mSQLException.toString());
throw mSQLException;
}
}
}您可以从设备上卸载应用程序并再次运行。如果以后在数据库上添加表,则不会反映该应用程序,因为您的数据库已经创建,并且只有在创建数据库时才创建表。您必须在创建方法中调用createDataBase方法
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
}
这就是这个方法的目的。
另外,如果您从任何其他地方调用它(我没有阅读您的全部代码),请不要这样做。但是,如果我发布应用程序时只有一个表,而现在我需要两个表,那么如何更新我的数据库以将该表添加到用户应用程序中呢?我无法卸载他们的应用程序。@marjanbaz--,您必须重写onUpdate方法。并在该方法上创建或更改表。我该怎么做?我什么都试过了,我是认真的。你可以看到。