我正在创建一个应用程序，我必须在其中打开以前创建的 SQLite 数据库。我正在使用 DBHelper 类。当我模拟应用程序时一切都很好，但是 logcat 显示以下错误：
10-31 17:59:56.345: I/Database(391): sqlite returned: error code = 14, msg = cannot open file at source line 25467
10-31 17:59:56.345: E/Database(391): sqlite3_open_v2("/data/data/com.proj.neuroq/databases/quiz.db", &handle, 1, NULL) failed
我的活动课：
public class QuestionActivity extends Activity {
String db_name="quiz";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_question);
DatabaseHelper myDbHelper = new DatabaseHelper(getBaseContext());
myDbHelper = new DatabaseHelper(this);
try {
myDbHelper.createDatabase();
} catch (IOException ioe) {
throw new Error("Unable to create database");
}
try {
myDbHelper.openDataBase();
}catch(SQLException sqle){
throw sqle;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_question, menu);
return true;
}
}
我的 DatabaseHelper 类：
public class DatabaseHelper extends SQLiteOpenHelper {
private static String DB_PATH = "/data/data/com.proj.neuroq/databases/";
private static String DB_NAME = "quiz.db";
private SQLiteDatabase db;
private final Context myContext;
public DatabaseHelper(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
}
/**
* 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.getReadableDatabase();
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 dosen't
*/
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try {
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
} catch (SQLiteException e) {
}
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;
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 + DB_NAME;
db = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if(db != null)
db.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
}
}
我的清单文件：
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.proj.neuroq"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".QuestionActivity"
android:label="@string/title_activity_question" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
这是我的项目结构：
这是我的logcat 输出：
我提到的链接：
http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/
http://snipplr.com/view.php?codeview&id=58589
棘手的问题在哪里？