KeyValueStore v2 is available here: https://www.b4x.com/android/forum/threads/b4x-keyvaluestore-2-simple-powerful-local-datastore.63633/
In many cases applications need to store all kinds of data.
Key / value data stores (sometimes referred as NoSQL) can offer an alternative to relational databases (SQL). The key / value store offers a simple functionality. It allows you to store all kinds of values, where each value is mapped to a key. Very similar to Maps (as well as Dictionary, Hashtable, HashMap...). The main difference is that the store is persisted in the file system.
KeyValueStore class uses an SQLite database to store and retrieve all kinds of values.
It uses RandomAccessFile.WriteObject or WriteEncryptedObject to save collections and user types.
Using KeyValueStore is similar to using a Map:
The public methods of KeyValueStore:
So if you do not need the more advanced features of a relational database then KeyValueStore is your probably best solution for data persisting.
The class is included in the attached example. It depends on the SQL and RandomAccessFile libraries.
V1.01 - Fixes an issue with open cursors.
In many cases applications need to store all kinds of data.
Key / value data stores (sometimes referred as NoSQL) can offer an alternative to relational databases (SQL). The key / value store offers a simple functionality. It allows you to store all kinds of values, where each value is mapped to a key. Very similar to Maps (as well as Dictionary, Hashtable, HashMap...). The main difference is that the store is persisted in the file system.
KeyValueStore class uses an SQLite database to store and retrieve all kinds of values.
It uses RandomAccessFile.WriteObject or WriteEncryptedObject to save collections and user types.
Using KeyValueStore is similar to using a Map:
B4X:
Sub Process_Globals
Private kvs As KeyValueStore
End Sub
Sub Activity_Create(FirstTime As Boolean)
If FirstTime Then
kvs.Initialize(File.DirDefaultExternal, "datastore")
End If
'put a "simple" value
kvs.PutSimple("time", DateTime.Now)
'fetch this value
Log(DateTime.Time(kvs.GetSimple("time")))
'put a Bitmap
kvs.PutBitmap("bitmap1", LoadBitmap(File.DirAssets, "asteroids.png"))
'fetch a bitmap
Activity.SetBackgroundImage(kvs.GetBitmap("bitmap1"))
'remove the bitmap from the store
kvs.Remove("bitmap1")
'add a collection
Dim list1 As List
list1.Initialize
For i = 1 To 10
list1.Add("Item #" & i)
Next
kvs.PutObject("list1", list1)
'fetch the collection
Dim list2 As List = kvs.GetObject("list1")
Log(list2)
'encrypt the list
kvs.PutEncyptedObject("encrypted list", list1, "topsecret")
Try
'note that if you run this example in Debug then it will break on this call. Press F5 to continue...
list2 = kvs.GetEncryptedObject("encrypted list", "wrong password")
Catch
Log("Wrong password!")
End Try
list2 = kvs.GetEncryptedObject("encrypted list", "topsecret")
Log(list2)
End SubThe public methods of KeyValueStore:
B4X:
'Puts a simple value in the store.
'Strings and number types are considered "simple" values.
Sub PutSimple(Key As String, Value As Object) As Boolean
'Puts an object in the store. This method uses RandomAccessFile.WriteObject to save the object in the store.
'It is capable of writing the following types of objects: Lists, Arrays, Maps, Strings, primitive types and user defined types.
'Combinations of these types are also supported. For example, a Map with several lists of arrays can be written.
'The element type inside a collection must be a String OR primitive Type.
Sub PutObject(Key As String, Value As Object) As Boolean
'Similar to PutObject. Encrypts the object before writing it. Note that you can use it to store "simple" types as well.
Sub PutEncyptedObject(Key As String, Value As Object, Password As String) As Boolean
'Puts a bitmap in the store.
Sub PutBitmap(Key As String, Value As Bitmap) As Boolean
'Reads the data from the input stream and saves it in the store.
Sub PutInputStream(Key As String, Value As InputStream) As Boolean
'Removes the key and value mapped to this key.
Sub Remove(Key As String)
'Returns a list with all the keys.
Sub ListKeys As List
'Tests whether a key is available in the store.
Sub ContainsKey(Key As String) As Boolean
'Deletes all data from the store.
Sub DeleteAll
'Returns a "simple" value. See PutSimple.
Sub GetSimple(Key As String) As String
'Returns an InputStream from the store. See PutInputStream.
Sub GetInputStream(Key As String) As InputStream
'Returns a bitmap from the store. See PutBitmap.
Sub GetBitmap(Key As String) As Bitmap
'Returns an object from the store. See PutObject.
Sub GetObject(Key As String) As Object
'Returns an encrypted object from the store. See PutEncryptedObject.
Sub GetEncryptedObject(Key As String, Password As String) As Object
'Closes the store.
Sub CloseSo if you do not need the more advanced features of a relational database then KeyValueStore is your probably best solution for data persisting.
The class is included in the attached example. It depends on the SQL and RandomAccessFile libraries.
V1.01 - Fixes an issue with open cursors.
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