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

java.lang.Object
  extended by 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
MqttDefaultFilePersistence()
           
MqttDefaultFilePersistence(String directory)
          Create an file-based persistent data store within the specified directory.
 
Method Summary
 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


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