org.eclipse.paho.client.mqttv3.persist

Class MqttDefaultFilePersistence

java.lang.Object

org.eclipse.paho.client.mqttv3.persist.MqttDefaultFilePersistence

All Implemented Interfaces:

MqttClientPersistence

public class MqttDefaultFilePersistence
extends Object
implements MqttClientPersistence

An implementation of the MqttClientPersistence interface that provides file based persistence. A directory is specified when the Persistence object is created. When the persistence is then opened (see open(String, String)), a sub-directory is made beneath the base for this client ID and connection key. This allows one persistence base directory to be shared by multiple clients. The sub-directory's name is created from a concatenation of the client ID and connection key with any instance of '/', '\\', ':' or ' ' removed.

Constructor Summary

Constructors

Constructor and Description
MqttDefaultFilePersistence()
MqttDefaultFilePersistence(String directory) Create an file-based persistent data store within the specified directory.

Method Summary

Modifier and Type	Method and Description
void	clear() Clears persistence, so that it no longer contains any persisted data.
void	close() Close the persistent store that was previously opened.
boolean	containsKey(String key) Returns whether or not data is persisted using the specified key.
MqttPersistable	get(String key) Gets the specified data out of the persistent store.
Enumeration	keys() Returns all of the persistent data from the previously specified persistence directory.
void	open(String clientId, String theConnection) Initialise the persistent store.
void	put(String key, MqttPersistable message) Writes the specified persistent data to the previously specified persistence directory.
void	remove(String key) Deletes the data with the specified key from the previously specified persistence directory.

Methods inherited from class java.lang.Object

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

Constructor Detail

MqttDefaultFilePersistence

public MqttDefaultFilePersistence()

MqttDefaultFilePersistence

public MqttDefaultFilePersistence(String directory)

Create an file-based persistent data store within the specified directory.

Parameters:

directory - the directory to use.

Method Detail

open

public void open(String clientId,
                 String theConnection)
          throws MqttPersistenceException

Description copied from interface: MqttClientPersistence

Initialise the persistent store. If a persistent store exists for this client ID then open it, otherwise create a new one. If the persistent store is already open then just return. An application may use the same client ID to connect to many different servers, so the client ID in conjunction with the connection will uniquely identify the persistence store required.

Specified by:

open in interface MqttClientPersistence

Parameters:

clientId - The client for which the persistent store should be opened.

theConnection - The connection string as specified when the MQTT client instance was created.

Throws:

MqttPersistenceException - if there was a problem opening the persistent store.

close

public void close()
           throws MqttPersistenceException

Description copied from interface: MqttClientPersistence

Close the persistent store that was previously opened. This will be called when a client application disconnects from the broker.

Specified by:

close in interface MqttClientPersistence

Throws:

MqttPersistenceException

put

public void put(String key,
                MqttPersistable message)
         throws MqttPersistenceException

Writes the specified persistent data to the previously specified persistence directory. This method uses a safe overwrite policy to ensure IO errors do not lose messages.

Specified by:

put in interface MqttClientPersistence

Parameters:

message -

key - the key for the data, which will be used later to retrieve it.

Throws:

MqttPersistenceException

get

public MqttPersistable get(String key)
                    throws MqttPersistenceException

Description copied from interface: MqttClientPersistence

Gets the specified data out of the persistent store.

Specified by:

get in interface MqttClientPersistence

Parameters:

key - the key for the data, which was used when originally saving it.

Returns:

the un-persisted data

Throws:

MqttPersistenceException - if there was a problem getting the data from the persistent store.

remove

public void remove(String key)
            throws MqttPersistenceException

Deletes the data with the specified key from the previously specified persistence directory.

Specified by:

remove in interface MqttClientPersistence

Throws:

MqttPersistenceException

keys

public Enumeration keys()
                 throws MqttPersistenceException

Returns all of the persistent data from the previously specified persistence directory.

Specified by:

keys in interface MqttClientPersistence

Returns:

all of the persistent data from the persistence directory.

Throws:

MqttPersistenceException

containsKey

public boolean containsKey(String key)
                    throws MqttPersistenceException

Description copied from interface: MqttClientPersistence

Returns whether or not data is persisted using the specified key.

Specified by:

containsKey in interface MqttClientPersistence

Parameters:

key - the key for data, which was used when originally saving it.

Throws:

MqttPersistenceException

clear

public void clear()
           throws MqttPersistenceException

Description copied from interface: MqttClientPersistence

Clears persistence, so that it no longer contains any persisted data.

Specified by:

clear in interface MqttClientPersistence

Throws:

MqttPersistenceException