SQLite的例外：数据库被锁定的问题 [英] SQLite exception: Database is locked issue
问题描述
我有我的里面一个Android应用程序SQLite数据库的问题。它似乎发生，每隔一段时间，我不能复制，但是这是报告中的Android市场提供。
I'm having an issue with my SQLite database inside an Android app. It seems to happen every so often and I cannot reproduce it, but this is the report the Android Market gives.
基本上，我必须先通过，如果所有需要的数据在数据库中检查启动闪屏的活动。如果不是，它将安装数据的异步线程，并关闭数据库连接。
Basically I have first a splash screen activity that starts by checking if all the needed data is in the database. If not, it will install the data in a asynchronous thread and close the db connection.
然后，然后才可以在主要活动启动，这也将打开，读取/写入数据库。
Then and only then can the main activity be started, which also opens and reads/writes the database.
这code从初始屏幕活动的onCreate方法执行：
This code is executed from the onCreate method of the splash screen activity:
dbWord = new WordDBAdapter(this, myUI);
dbWord.open();
if (dbWord.isDataInstalled()) {
dbWord.close();
databaseInstalled = true;
clickToStartView.setText(myUI.PRESS_TO_START);
clickToStartView.startAnimation(myBlinkAnim);
} else {
// If not, try to install in asynchronous thread
progressDialog = new ProgressDialog(this);
progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
progressDialog.setMessage(myUI.INSTALLING_DB);
progressDialog.setCancelable(false);
new InstallDBData().execute("");
}
在code异步线程是：
The code for the asynchronous thread is:
private class InstallDBData extends AsyncTask<String, Integer, Integer> {
@Override
protected Integer doInBackground(String... arg0) {
progressDialog.setProgress(0);
dbWord.installData(0, getApplicationContext());
progressDialog.setProgress(20);
dbWord.installData(1, getApplicationContext());
progressDialog.setProgress(40);
dbWord.installData(2, getApplicationContext());
progressDialog.setProgress(60);
dbWord.installData(3, getApplicationContext());
progressDialog.setProgress(80);
dbWord.installData(4, getApplicationContext());
progressDialog.setProgress(100);
return 1;
}
protected void onPreExecute() {
progressDialog.show();
}
protected void onPostExecute(Integer x) {
dbWord.close();
progressDialog.hide();
databaseInstalled = true;
clickToStartView.setText(myUI.PRESS_TO_START);
clickToStartView.startAnimation(myBlinkAnim);
}
}
这些都是WordDBAdapter类，它也被用于由主活动的重要部分：
These are important parts of the WordDBAdapter class, which is also used by the main activity:
public class WordDBAdapter {
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;
public WordDBAdapter open() throws android.database.SQLException {
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
return this;
}
public void close() {
mDbHelper.close();
}
...
}
我发现了以下情况除外，这是类似的，但有一个不同的消息：
I'm getting the following exceptions, which are similar but have a different message:
第一类型的错误消息：
java.lang.RuntimeException: Unable to start activity
ComponentInfo{example.flashcards.medical/com.example.flashcards.common.SplashWindow}:
android.database.sqlite.SQLiteException: database is locked: BEGIN EXCLUSIVE;
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1830)
....
Caused by: android.database.sqlite.SQLiteException: database is locked: BEGIN EXCLUSIVE;
at android.database.sqlite.SQLiteDatabase.native_execSQL(Native Method)
at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1870)
at android.database.sqlite.SQLiteDatabase.beginTransactionWithListener(SQLiteDatabase.java:602)
二类型的错误消息：
Second type of error message:
java.lang.RuntimeException: Unable to start activity
ComponentInfo{example.flashcards.medical/com.example.flashcards.common.SplashWindow}:
android.database.sqlite.SQLiteException: database is locked
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1768)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1784)
....
Caused by: android.database.sqlite.SQLiteException: database is locked
at android.database.sqlite.SQLiteDatabase.native_setLocale(Native Method)
at android.database.sqlite.SQLiteDatabase.setLocale(SQLiteDatabase.java:1987)
at android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1855)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:820)
at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:854)
我真的很想不必创建一个ContentProvider的，因为我相信它的矫枉过正，如果一个简单的解决方法是可用的。此外，只有本申请有权访问数据库。
I would really like to not have to create a ContentProvider, because I believe its overkill if a simpler solution is available. Also, only this application has access to the database.
在如何可以修复有什么建议？
Any suggestions on how this can be fixed?
推荐答案
做了一些努力，我做到了（我的应用程序正在研究完善到了Android 2.3，但得到了分贝锁定错误，当我用的蜂窝平板运行）之后。
我没有使用信号量（使用锁在临界区）。
After doing some effort I did it (My app was working on perfect till android 2.3 but got db lock error when I used to run it on HoneyComb tablet).
I did using Semaphores (using lock in critical sections).
示例1
public class DbExp extends SQLiteOpenHelper{
public static String Lock = "dblock";
private static final String DATABASE_NAME = "db.db";
private static final String TABLE_NAME = "table_name";
public void delete(Context mContext){
synchronized(Lock) {
SQLiteDatabase db = getWritableDatabase();
db.delete(TABLE_NAME, null, null);
db.close();
}
}
public void insert(){
synchronized(Lock) {
SQLiteDatabase db = getWritableDatabase();
db.insert(TABLE_NAME, ..., ...);
db.close();
}
}
}
例2
public class DB {
public static String Lock = "dblock";
private static final String DATABASE_NAME = "db.db";
private static final String TABLE_NAME = "table_name";
public void delete(Context mContext){
synchronized(Lock) {
SQLiteDatabase db = mContext.openOrCreateDatabase(DATABASE_NAME, Context.MODE_PRIVATE, null);
db.delete(TABLE_NAME, null, null);
db.close();
}
}
public void insert(Context mContext){
synchronized(Lock) {
SQLiteDatabase db = mContext.openOrCreateDatabase(DATABASE_NAME, Context.MODE_PRIVATE, null);
db.insert(TABLE_NAME, ..., ...);
db.close();
}
}
}
希望这将有助于任何人在将来的：）
Hope this would help Anyone in future :)
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