在我的应用程序中，我必须从assets文件夹中检索sqlite数据库。但是当我这样做时，我会收到错误。
这是我用来从资产中复制数据库的编码
public class DataBaseHelper 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 ="(student).sqlite";// Database name
private SQLiteDatabase mDataBase;
private final Context mContext;
public DataBaseHelper(Context context)
{
super(context, DB_NAME, null, 1);// 1? its Database Version
DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
Log.i(TAG, DB_PATH);
this.mContext = context;
}
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 arg0) {
// TODO Auto-generated method stub
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
}
调用数据库编码
public class TestAdapter {
protected static final String TAG = "DataAdapter";
private Context mContext;
public static SQLiteDatabase mDb;
private DataBaseHelper mDbHelper;
public static TestAdapter instance;
public TestAdapter(Context context) {
this.mContext = context;
mDbHelper = new DataBaseHelper(mContext);
createDatabase();
open();
}
public static TestAdapter getTestAdaptor(Context context) {
if (instance == null) {
instance = new TestAdapter(context);
// createDatabase();
// open();
}
return instance;
}
private void createDatabase() throws SQLException {
try {
mDbHelper.createDataBase();
} catch (IOException mIOException) {
Log.e(TAG, mIOException.toString() + " UnableToCreateDatabase");
throw new Error("UnableToCreateDatabase");
}
}
private void open() throws SQLException {
try {
mDbHelper.openDataBase();
mDbHelper.close();
mDb = mDbHelper.getReadableDatabase();
} catch (SQLException mSQLException) {
Log.e(TAG, "open >>" + mSQLException.toString());
throw mSQLException;
}
}
public void close() {
mDbHelper.close();
}
这是我得到的错误
03-14 10:18:03.731: E/AndroidRuntime(788): FATAL EXCEPTION: main
03-14 10:18:03.731: E/AndroidRuntime(788): java.lang.Error: ErrorCopyingDataBase
03-14 10:18:03.731: E/AndroidRuntime(788): at com.example.voicereg.DataBaseHelper.createDataBase(DataBaseHelper.java:49)
03-14 10:18:03.731: E/AndroidRuntime(788): at com.example.voicereg.TestAdapter.createDatabase(TestAdapter.java:38)
03-14 10:18:03.731: E/AndroidRuntime(788): at com.example.voicereg.TestAdapter.<init>(TestAdapter.java:23)
03-14 10:18:03.731: E/AndroidRuntime(788): at com.example.voicereg.TestAdapter.getTestAdaptor(TestAdapter.java:29)
03-14 10:18:03.731: E/AndroidRuntime(788): at com.example.voicereg.VoiceActivity.onOptionsItemSelected(VoiceActivity.java:186)
03-14 10:18:03.731: E/AndroidRuntime(788): at android.app.Activity.onMenuItemSelected(Activity.java:2502)
03-14 10:18:03.731: E/AndroidRuntime(788): at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:950)
03-14 10:18:03.731: E/AndroidRuntime(788): at com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:735)
03-14 10:18:03.731: E/AndroidRuntime(788): at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:149)
03-14 10:18:03.731: E/AndroidRuntime(788): at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:874)
03-14 10:18:03.731: E/AndroidRuntime(788): at com.android.internal.view.menu.ListMenuPresenter.onItemClick(ListMenuPresenter.java:163)
03-14 10:18:03.731: E/AndroidRuntime(788): at android.widget.AdapterView.performItemClick(AdapterView.java:292)
03-14 10:18:03.731: E/AndroidRuntime(788): at android.widget.AbsListView.performItemClick(AbsListView.java:1058)
03-14 10:18:03.731: E/AndroidRuntime(788): at android.widget.AbsListView$PerformClick.run(AbsListView.java:2514)
03-14 10:18:03.731: E/AndroidRuntime(788): at android.widget.AbsListView$1.run(AbsListView.java:3168)
03-14 10:18:03.731: E/AndroidRuntime(788): at android.os.Handler.handleCallback(Handler.java:605)
03-14 10:18:03.731: E/AndroidRuntime(788): at android.os.Handler.dispatchMessage(Handler.java:92)
03-14 10:18:03.731: E/AndroidRuntime(788): at android.os.Looper.loop(Looper.java:137)
03-14 10:18:03.731: E/AndroidRuntime(788): at android.app.ActivityThread.main(ActivityThread.java:4424)
03-14 10:18:03.731: E/AndroidRuntime(788): at java.lang.reflect.Method.invokeNative(Native Method)
03-14 10:18:03.731: E/AndroidRuntime(788): at java.lang.reflect.Method.invoke(Method.java:511)
03-14 10:18:03.731: E/AndroidRuntime(788): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
03-14 10:18:03.731: E/AndroidRuntime(788): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
03-14 10:18:03.731: E/AndroidRuntime(788): at dalvik.system.NativeStart.main(Native Method)
任何人都可以帮助我在编码部分做错了什么
答案 0 :(得分：0)
在createDatabase中，您关闭数据库，因此无法复制
this.getReadableDatabase();
this.close();
应该只是
this.getReadableDatabase();