com.neovisionaries.android.database

Class BaseOpenHelper

java.lang.Object

android.database.sqlite.SQLiteOpenHelper

com.neovisionaries.android.database.BaseOpenHelper

public abstract class BaseOpenHelper
extends android.database.sqlite.SQLiteOpenHelper

Database open helper with a read/write lock, which is useful when a database needs to be accessed by multiple threads.

 // A subclass of BaseOpenHelper.
 MyOpenHelper helper = ...;

 SQLiteDatabase db = null;

 try
 {
     // Open the database in read mode. openReadable()
     // acquires a read lock and then opens the database
     // by getReadableDatabase().
     db = helper.openReadable();

     ......
 }
 finally
 {
     // Close the database and release the read lock.
     helper.closeReadable(db);
 }

Since:

1.8

Author:

Takahiko Kawasaki

Constructor Summary

Constructors

Constructor and Description
BaseOpenHelper(android.content.Context context, String name, android.database.sqlite.SQLiteDatabase.CursorFactory factory, int version) Constructor.
BaseOpenHelper(int version) Constructor.
BaseOpenHelper(android.database.sqlite.SQLiteDatabase.CursorFactory factory, int version) Constructor.
BaseOpenHelper(String name, android.database.sqlite.SQLiteDatabase.CursorFactory factory, int version) Constructor.

Method Summary

Modifier and Type	Method and Description
void	closeReadable(android.database.sqlite.SQLiteDatabase db) Close a database which has been opened by openReadable().
void	closeWritable(android.database.sqlite.SQLiteDatabase db) Close a database which has been opened by openWritable().
ReentrantReadWriteLock	getLock() Get the internal read-write lock instance.
android.database.sqlite.SQLiteDatabase	openReadable() Open the database in read mode.
android.database.sqlite.SQLiteDatabase	openWritable() Open the database in write mode.

Methods inherited from class android.database.sqlite.SQLiteOpenHelper

close, getReadableDatabase, getWritableDatabase, onCreate, onOpen, onUpgrade

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BaseOpenHelper

public BaseOpenHelper(android.content.Context context,
                      String name,
                      android.database.sqlite.SQLiteDatabase.CursorFactory factory,
                      int version)

Constructor. This constructor does the following.

 super(context, name, factory, version);

BaseOpenHelper

public BaseOpenHelper(String name,
                      android.database.sqlite.SQLiteDatabase.CursorFactory factory,
                      int version)

Constructor. This constructor does the following.

 this(App.getInstance().getContext(), name, factory, version);

BaseOpenHelper

public BaseOpenHelper(android.database.sqlite.SQLiteDatabase.CursorFactory factory,
                      int version)

Constructor. This constructor does the following.

 this(App.getInstance().getContext().getPackageName(), factory, version);

BaseOpenHelper

public BaseOpenHelper(int version)

Constructor. This constructor does the following.

 this(null, version);

Method Detail

openReadable

public android.database.sqlite.SQLiteDatabase openReadable()

Open the database in read mode.

This method acquires a read lock first, then calls SQLiteOpenHelper.getReadableDatabase(). If getReadableDatabase() throws an SQLiteException, the read lock is released and the exception is re-thrown. The SQLiteDatabase instance returned by this method has to be closed by closeReadable(SQLiteDatabase), not by SQLiteDatabase.close(). Otherwise, the read lock is not released.

closeReadable

public void closeReadable(android.database.sqlite.SQLiteDatabase db)

Close a database which has been opened by openReadable().

This method closes the passed database by calling db.close() and then releases a read lock (even if db.close() failed).

Parameters:

db - A database which has been opened by openReadable(). If null is given, nothing is done (any read lock is released).

openWritable

public android.database.sqlite.SQLiteDatabase openWritable()

Open the database in write mode.

This method acquires a write lock first, then calls SQLiteOpenHelper.getWritableDatabase(). If getWritableDatabase() throws an SQLiteException, the write lock is released and the exception is re-thrown. The SQLiteDatabase instance returned by this method has to be closed by closeWritable(SQLiteDatabase), not by SQLiteDatabase.close(). Otherwise, the write lock is not released.

closeWritable

public void closeWritable(android.database.sqlite.SQLiteDatabase db)

Close a database which has been opened by openWritable().

This method closes the passed database by calling db.close() and then releases a write lock (even if db.close() failed).

Parameters:

db - A database which has been opened by openWritable(). If null is given, nothing is done (any write lock is released).

getLock

public ReentrantReadWriteLock getLock()

Get the internal read-write lock instance.