SQLite数据库使用线程锁定的问题：Android版 [英] Sqlite Database locked issue using threading : Android
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问题描述
我有关于sqlitedatabase.i必须创建两个thread.one是Web服务调用，并插入到数据库和第二线程用于检索所有数据库data.but我得到了一些错误的一些问题：
I have some issue relating sqlitedatabase.i have create two thread.one is for webservice call and insert into database and second thread is for retrieving all database data.but i got some error:
09-18 13:45:48.724: E/SQLiteDatabase(7189): android.database.sqlite.SQLiteDatabaseLockedException: database is locked (code 5): , while compiling: PRAGMA journal_mode
我的code是如下：
my code is below:
Mainactivity.java
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
dbHelper = new DbHelper(this);
setContentView(R.layout.activity_main);
try {
dbHelper.createDataBase();
} catch (IOException e) {
e.printStackTrace();
}
new Thread(new Runnable() {
@Override
public void run() {
try {
Log.i("data", "webAllBrokers thread start");
GetAllBrokers(getApplicationContext());
// GetAllBrokers(getApplicationContext());
Log.i("data", "webAllBrokers thread complete");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (XmlPullParserException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}).start();
new Thread(new Runnable() {
@Override
public void run() {
Log.i("data", "SelectAllData thread start.");
SelectAllData();
Log.i("data", "SelectAllData thread complete");
}
}).start();
}
private void SelectAllData() {
// TODO Auto-generated method stub
for (int i = 0; i < 100; i++) {
TblBroker.SelectAll(dbHelper);
}
}
public static void GetAllBrokers(Context context) throws IOException,
XmlPullParserException, JSONException {
// webservice call for retrieve data
String result = GetAllBrokers(context, "Admin001");
ArrayList<ModelBroker> lstBrokers = JsonParserGetAllBrokers
.parserString(result);
TblBroker.deleteAll(dbHelper);
TblBroker.insert(dbHelper, lstBrokers);
}
另一个文件是dbhelper文件：
the other file is dbhelper file:
DbHelper.java
public class DbHelper extends SQLiteOpenHelper {
// The Android's default system path of your application database.
private static String PACKAGENAME = "com.example.webservicedemocallbackgroundwebservice";
private static String DB_PATH = "/data/data/" + PACKAGENAME + "/databases/";
private static String DB_NAME = "GRSL_Sales_DB.sqlite";
public static int DELETED = 1;
public static int UPDATED = 2;
public static int NEW_RECORD = 3;
private final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();
private final Lock r = rwl.readLock();
private final Lock w = rwl.writeLock();
private SQLiteDatabase myDataBase;
private final Context myContext;
private String TAG = "DbHelper";
/**
* Constructor Takes and keeps a reference of the passed context in order to
* access to the application assets and resources.
*
* @param context
*/
public DbHelper(final 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 final void createDataBase() throws IOException {
final boolean dbExist = checkDataBase();
SQLiteDatabase db_Read = null;
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.
// 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.
// db_Read = this.getReadableDatabase(DB_Internal);
db_Read = this.getReadableDatabase();
db_Read.close();
copyDataBase();
}
}
/**
* Restore whole database without any data
*
* @throws IOException
*/
public final void RestoreDatabase() throws IOException {
SQLiteDatabase db_Read = this.getReadableDatabase();
db_Read.close();
copyDataBase();
Log.i(TAG, "Database REstored");
}
/**
* 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() {
final File dbFile = new File(DB_PATH + DB_NAME);
return dbFile.exists();
}
/**
* 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.
*
* @throws IOException
* */
private void copyDataBase() throws IOException {
// Open your local db as the input stream
final InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
final String outFileName = DB_PATH + DB_NAME;
// Open the empty db as the output stream
final OutputStream myOutput = new FileOutputStream(outFileName);
// transfer bytes from the inputfile to the outputfile
final 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 final synchronized SQLiteDatabase openDataBase() {
// Log.i("data", "data openDataBase");
// Open the database
final String myPath = DB_PATH + DB_NAME;
Log.i("database", "data openDataBase" + myDataBase);
if (myDataBase == null) {
Log.i("database", "data openDataBase");
myDataBase = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READWRITE);
myDataBase.beginTransaction();
}
return myDataBase;
}
@Override
public final synchronized void close() {
// Log.i("data", "data closeDataBase");
if (myDataBase != null) {
Log.i("database", "data closeDataBase");
myDataBase.setTransactionSuccessful();
myDataBase.endTransaction();
myDataBase.close();
myDataBase = null;
}
super.close();
}
@Override
public void onCreate(final SQLiteDatabase arg0) {
}
@Override
public void onUpgrade(final SQLiteDatabase arg0, final int arg1,
final int arg2) {
}
}
我的表文件是：
TblBroker.java
public class TblBroker {
public static final String TABLENAME = "Broker";
public static final String ID = "ID";
public static final String SAPCODE = "SAPCode";
public static final String DISCRIPTION = "Discription";
public static final String ISACTIVE = "IsActive";
public static final String ISDELETED = "IsDeleted";
public static final String City = "City";
/**
*
* SelectAll
*
* @param dbaConnection
* @return ArrayList<ModelBroker>
*/
public static ArrayList<ModelBroker> SelectAll(DbHelper dbaConnection) {
Log.i("data", "SelectAll start");
ArrayList<ModelBroker> broker_aList = new ArrayList<ModelBroker>();
SQLiteDatabase sqldb = dbaConnection.openDataBase();
Cursor cursor = sqldb.rawQuery("Select * From " + TblBroker.TABLENAME,
null);
if (cursor != null && !cursor.isClosed())// If CursorBroker is null then
// do
// nothing
{
if (cursor.moveToFirst()) {
do {
// Set broker information in model.
ModelBroker modelBroker = new ModelBroker();
modelBroker.setID(cursor.getInt(cursor
.getColumnIndex(TblBroker.ID)));
modelBroker.setSAPCode(cursor.getString(cursor
.getColumnIndex(TblBroker.SAPCODE)));
modelBroker.setDiscription(cursor.getString(cursor
.getColumnIndex(TblBroker.DISCRIPTION)));
modelBroker.setIsDeleted(cursor.getString(cursor
.getColumnIndex(TblBroker.ISDELETED)));
modelBroker.setIsActive(cursor.getString(cursor
.getColumnIndex(TblBroker.ISACTIVE)));
modelBroker.setCity(cursor.getString(cursor
.getColumnIndex(TblBroker.City)));
broker_aList.add(modelBroker);
} while (cursor.moveToNext());
}
cursor.close();
}
Log.i("data", "SelectAll end");
dbaConnection.close();
return broker_aList;
}
public static long insert(DbHelper dbaConnection,
ArrayList<ModelBroker> listbroker) {
long id = 0;
SQLiteDatabase sqldb = dbaConnection.openDataBase();
for (int i = 0; i < listbroker.size(); i++) {
ModelBroker broker = listbroker.get(i);
ContentValues values = new ContentValues();
values.put(TblBroker.SAPCODE, broker.getSAPCode());
values.put(TblBroker.DISCRIPTION, broker.getDiscription());
values.put(TblBroker.ISACTIVE, broker.getIsActive());
values.put(TblBroker.ISDELETED, broker.getIsDeleted());
values.put(TblBroker.City, broker.getCity());
Log.i("data", "sqldb.isOpen()=" + sqldb.isOpen());
id = sqldb.insert(TblBroker.TABLENAME, null, values);
}
Log.i("data", "1 st loop end");
Log.i("data", "2nd loop start");
for (int i = 0; i < listbroker.size(); i++) {
ModelBroker broker = listbroker.get(i);
ContentValues values = new ContentValues();
values.put(TblBroker.SAPCODE, broker.getSAPCode());
values.put(TblBroker.DISCRIPTION, broker.getDiscription());
values.put(TblBroker.ISACTIVE, broker.getIsActive());
values.put(TblBroker.ISDELETED, broker.getIsDeleted());
values.put(TblBroker.City, broker.getCity());
id = sqldb.insert(TblBroker.TABLENAME, null, values);
}
Log.i("data", "2nd loop end");
// Insert
// query
// of
// SQLiteDatabase
// class.
dbaConnection.close();
return id;
}
public static int deleteAll(DbHelper dbaConnection) {
SQLiteDatabase sqldb = dbaConnection.openDataBase();
int row = sqldb.delete(TABLENAME, null, null);// Delete
sqldb.close();
sqldb = null;
return row;
}
}
请给我一些solution.when一个线程在运行并打开数据库，然后在那个时候其他线程是开放db.so请找并发问题的解决方案。
please give me some solution.when one thread is running and open db then at that time other thread is open db.so please find solution of concurrency problem.
推荐答案
sqlite的默认运行在序列化模式在Android 。这意味着，多个线程可同时访问的数据库和线程安全是通过使用同步锁保持。
Sqlite runs in Serialized mode on Android by default. This means that multiple threads can access the database simultaneously and thread-safety is maintained by using synchronized locks.
您可以通过使用<一个关闭此功能href=\"https://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html#setLockingEnabled%28boolean%29\">setLockingEnabled(boolean lockingEnabled）。这将，但是，让你的分贝不安全的，你必须要小心处理和同步自己。
You can turn this off by using setLockingEnabled(boolean lockingEnabled). This will, however, make your db unsafe and you'll have to be careful and handle the synchronization yourself.
我猜你的问题就出在你的架构比线程多。我建议你重新考虑你的应用程序的体系结构，使您不必围绕破解你的分贝的线程安全的特点。
I would guess your problem lies in your architecture more than the threading. I suggest you re-think the architecture of your app so that you don't have to hack around with the thread-safety features of your db.
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