问题
I know this question has been asked before. But, the problem is, the same code (for database handler) is working for another app, but not the one I'm currently working on. I've even made sure the permissions are given by checking the permissions in settings. Here's the logcat:
05-13 15:35:45.693 29696-29696/com.example.hack.corrector E/SQLiteLog: (14) cannot open file at line 31282 of [5a3022e081] (14) os_unix.c:31282: (21) open(/data/user/0/com.example.hack.corrector/databases/) - 05-13 15:35:45.694 29696-29696/com.example.hack.corrector E/SQLiteDatabase: Failed to open database '/data/user/0/com.example.hack.corrector/databases/'. android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method) at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:207) at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:191) at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:463) at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:185) at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:177) at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:806) at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:791) at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:694) at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:669) at com.example.hakc.corrector.VocabDatabase.openDataBase(VocabDatabase.java:127) at com.example.hakc.corrector.scrapeservice.createDB(scrapeservice.java:31) at com.example.hakc.corrector.scrapeservice.onStartCommand(scrapeservice.java:23) at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3049) at android.app.ActivityThread.access$2300(ActivityThread.java:154) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1479) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:157) at android.app.ActivityThread.main(ActivityThread.java:5571) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:745) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:635)
and here's the database handler code:
package com.example.hack.corrector;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
public class VocabDatabase extends SQLiteOpenHelper {
//The Android's default system path of your application database.
private static String DB_PATH = "";
private static String DB_NAME = "ztr.db";
private SQLiteDatabase myDataBase;
private final Context myContext;
/**
* Constructor
* Takes and keeps a reference of the passed context in order to access to the application assets and resources.
*
* @param context
*/
public VocabDatabase(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
this.DB_PATH = context.getApplicationInfo().dataDir + "/databases/";
}
/**
* Creates a empty database on the system and rewrites it with your own database.
*/
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if (dbExist) {
//do nothing - database already exist
} else {
//By calling this method and empty database will be created into the default system path
//of your application so we are gonna be able to overwrite that database with our database.
this.getWritableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
*
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase() {
this.getReadableDatabase();
SQLiteDatabase checkDB = null;
try {
String myPath = DB_PATH;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
} catch (SQLiteException e) {
e.printStackTrace();
}
if (checkDB != null) {
checkDB.close();
}
return (checkDB != null) ? true : false;
}
/**
* 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.
*/
private 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 = 0;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException {
//Open the database
String myPath = DB_PATH;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
@Override
public synchronized void close() {
if (myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
if (newVersion > oldVersion) {
try {
copyDataBase();
} catch (Exception e) {
e.printStackTrace();
}
}
}
// Add your public helper methods to access and get content from the database.
// You could return cursors by doing "return myDataBase.query(....)" so it'd be easy
// to you to create adapters for your views.
//add your public methods for insert, get, delete and update data in database.
public Cursor query(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy) {
SQLiteDatabase db = this.getWritableDatabase();
return db.query(table, columns, selection, selectionArgs, groupBy, having, orderBy);
}
public long insert(String table, String nullColumnHack, ContentValues contentValues) {
SQLiteDatabase db = this.getWritableDatabase();
return db.insert(table, nullColumnHack, contentValues);
}
public Cursor rawQuery(String string, String[] selectionArguments) {
SQLiteDatabase db = this.getWritableDatabase();
return db.rawQuery(string, selectionArguments);
}
}
I've checked the file explorer and the database has been copied and in place. But still, the error is occurring. I've never had problem with the other application that was implementing the same database handler code (Vocabdatabase). I've spent one and half a day trying to solve this problem but nothing is working...
回答1:
Your issue is that you are trying to open using a path that does not include the database name.
i.e. the unable to open 14 is for
/data/user/0/com.example.hack.corrector/databases/
whilst the open should be attempting to open
/data/user/0/com.example.hack.corrector/databases/ztr.db
Not using the full path will result in two issues which may well result in confusion.
- The messages will be issued when you check the Database for it's existence (note that as such the database would be copied every time as the database would never be found(opened))
- The messages will also be issued when you try to open the database, the latter failing.
In both situations the correct use should be DB_PATH + DB_NAME, not just DB_PATH.
The following is your Database Handler rewritten to incorporate the above but also to change the check for the database to be a check for the file so the open error 14 that is not an error isn't displayed (when the database is copied from the assets file).
- Comments
//<<<< ????indicate changes.
:-
public class VocabDatabase extends SQLiteOpenHelper {
//The Android's default system path of your application database.
//private static String DB_PATH = ""; //<<<< RMVD
private static String DB_PATH_ALT; //<<<< ADDED
private static String DB_NAME = "ztr.db";
private SQLiteDatabase myDataBase;
private final Context myContext;
/**
* Constructor
* Takes and keeps a reference of the passed context in order to access to the application assets and resources.
*
* @param context
*/
public VocabDatabase(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
//this.DB_PATH = context.getApplicationInfo().dataDir + "/databases/"; //<<<< RMVD
this.DB_PATH_ALT = context.getDatabasePath(DB_NAME).getPath(); //<<<< ADDED
}
/**
* Creates a empty database on the system and rewrites it with your own database.
*/
public void createDataBase() throws IOException {
//boolean dbExist = checkDataBase(); //<<<< RMVD
boolean dbExist = checkDataBaseAlt(); //<<<< CHANGED
if (dbExist) {
//do nothing - database already exist
} else {
//By calling this method and empty database will be created into the default system path
//of your application so we are gonna be able to overwrite that database with our database.
this.getWritableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
//<<<< ADDED Alternative method checks the file rather than database
//<<<< as such no open error 14 messages
/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
*
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBaseAlt() {
//File chkdb = new File(myContext.getDatabasePath(DB_NAME).getPath()); //<<<< RMVD
File chkdb = new File(DB_PATH_ALT); //<<<< ADDED
return chkdb.exists();
}
/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
*
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase() {
this.getReadableDatabase();
SQLiteDatabase checkDB = null;
try {
//String myPath = DB_PATH; //<<<< RMVD so no open error 14 uses alt method
checkDB = SQLiteDatabase.openDatabase(
DB_PATH_ALT, //<<<< CHANGED
null,
SQLiteDatabase.OPEN_READWRITE
);
} catch (SQLiteException e) {
e.printStackTrace();
}
if (checkDB != null) {
checkDB.close();
}
return checkDB != null; //<<<< simplified
}
/**
* 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.
*/
private void copyDataBase() throws IOException {
//Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME); //<<<< CHANGED
// 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(DB_PATH_ALT); //<<<< CHANGED
//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length = 0;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException {
//Open the database
//String myPath = DB_PATH; //<<<< RMVD
myDataBase = SQLiteDatabase.openDatabase(
DB_PATH_ALT, //<<<< CHANGED
null,
SQLiteDatabase.OPEN_READWRITE
);
}
@Override
public synchronized void close() {
if (myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
if (newVersion > oldVersion) {
try {
copyDataBase();
} catch (Exception e) {
e.printStackTrace();
}
}
}
// Add your public helper methods to access and get content from the database.
// You could return cursors by doing "return myDataBase.query(....)" so it'd be easy
// to you to create adapters for your views.
//add your public methods for insert, get, delete and update data in database.
public Cursor query(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy) {
SQLiteDatabase db = this.getWritableDatabase();
return db.query(table, columns, selection, selectionArgs, groupBy, having, orderBy);
}
public long insert(String table, String nullColumnHack, ContentValues contentValues) {
SQLiteDatabase db = this.getWritableDatabase();
return db.insert(table, nullColumnHack, contentValues);
}
public Cursor rawQuery(String string, String[] selectionArguments) {
SQLiteDatabase db = this.getWritableDatabase();
return db.rawQuery(string, selectionArguments);
}
}
来源：https://stackoverflow.com/questions/50315910/code-14-unable-to-open-database