scone.netobjects
Class NetNodeCache

java.lang.Object
  java.util.Observable
      scone.netobjects.NetNodeCache

All Implemented Interfaces:

TableRecordCacheInterface

public class NetNodeCache
extends java.util.Observable
implements TableRecordCacheInterface

Caches all NetNode objects.
Use the static methods provided by this class to obtain NetNode objects.

Author:

Harald Weinreich, Volkert Buchmann

Field Summary

protected static CacheTable	cache key1=id key2=uri
protected java.util.Vector	items
static java.lang.Object	lock used to synchronize this cache
protected static NetNodeCache	observable
protected static int	observePeriod

Method Summary

protected void	addItem(java.lang.Object o)
static void	clean() stores the cached NetNodes and removes empty entries from the cache.
static NetNode	get(NetNode base, java.lang.String link) get/create a NetNode by NetNodebase and link
static NetNode	get(SimpleUri sUri) get/create a NetNode by SimpleUri NetNodes are stored only on demand or if cache cleaer (@link{CacheTable}) is running.
static NetNode	get(SimpleUri sUri, boolean persistent) get/create a NetNode by SimpleUri
static NetNode	get(java.lang.String uriString) get/create a NetNode by plain String
static NetNode	get(java.lang.String id, boolean persistent) returns the NetNode stored in the database under the specified id.
static NetNode	getById(java.lang.String id) returns the NetNode stored in the database under the specified id.
static int	getNetNodeCount(java.lang.String sqlClause) This method returns a number of NetNodes to a given query string.
static int	getNetNodeCount(java.lang.String tables, java.lang.String sqlClause) This method returns a number of NetNodes to a given query string.
static java.util.Vector	getNetNodes(java.lang.String sqlClause) This method returns a Vector of NetNodes to a given query string
static int	getObservePeriod() returns how long the cache waits until it notifies Observers about new events
static void	init(int timeTillCleanUp, int gcType) Create a new cache for NetNodes.
void	notifyObservers()
static void	putObserver(java.util.Observer o) adds an Observer to the NetNodeCache class.
static void	removeObserver(java.util.Observer o) removes an Observer from the NetNodeCache class.
static void	setObservePeriod(int period) sets how long the cache waits until it notifies Observers about new events

Methods inherited from class java.util.Observable

addObserver, clearChanged, countObservers, deleteObserver, deleteObservers, hasChanged, notifyObservers, setChanged

Methods inherited from class java.lang.Object

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

Field Detail

observable

protected static NetNodeCache observable

observePeriod

protected static int observePeriod

cache

protected static CacheTable cache

key1=id
key2=uri

lock

public static java.lang.Object lock

used to synchronize this cache

items

protected java.util.Vector items

Method Detail

init

public static void init(int timeTillCleanUp,
                        int gcType)

Create a new cache for NetNodes.

Parameters:

timeTillCleanUp - Interval to store objects from cache to database

gcType - Garbage collector type: LAZYGC or EAGERGC. See CacheTable.java

setObservePeriod

public static void setObservePeriod(int period)

sets how long the cache waits until it notifies Observers about new events

Parameters:

period - the period in miliseconds

getObservePeriod

public static int getObservePeriod()

returns how long the cache waits until it notifies Observers about new events

Returns:

the peroid in miliseconds

putObserver

public static void putObserver(java.util.Observer o)

adds an Observer to the NetNodeCache class.
Use this static method instead of addObserver() !

Parameters:

o - the Observer

removeObserver

public static void removeObserver(java.util.Observer o)

removes an Observer from the NetNodeCache class.
Use this static method instead of deleteObserver() !

Parameters:

o - the Observer

get

public static NetNode get(java.lang.String uriString)

get/create a NetNode by plain String

Parameters:

uriString - the String representation of the URI of the node

get

public static NetNode get(NetNode base,
                          java.lang.String link)

get/create a NetNode by NetNodebase and link

Parameters:

base - the NetNode of the present page

link - the String declared by the link

get

public static NetNode get(SimpleUri sUri)

get/create a NetNode by SimpleUri
NetNodes are stored only on demand or if cache cleaer (@link{CacheTable}) is running. This Method does not changethe state of NetNodes (persistent / non-persistent) of NetNodes already cached.

If the netNode shall be made persistent immediately, call get(SimpleUri, true).
If new NetNodes shall not be made persistent, call get(SimpleUri, false).
To explicitly change the state of a NetNode call @link{TableRecord#setPersistent}

Parameters:

sUri - the URI

get

public static NetNode get(SimpleUri sUri,
                          boolean persistent)

get/create a NetNode by SimpleUri

Parameters:

sUri - the URI

persistent - shall the NetNode be made persistent?
true: yes, write NOW to database
false: no, never. netNode.setPersistent is set to false
For deferred DB persistency call get-method without boolean parameter.

getById

public static NetNode getById(java.lang.String id)

returns the NetNode stored in the database under the specified id.

Parameters:

id - the id

Returns:

the NetNode or null if it does not exist

get

public static NetNode get(java.lang.String id,
                          boolean persistent)

returns the NetNode stored in the database under the specified id.

Parameters:

sUri - the URI

persistent - shall the NetNode be made persistent?
true: yes, now,
false: no never.
For deferred DB persistency call get-method without boolean parameter.

getNetNodes

public static java.util.Vector getNetNodes(java.lang.String sqlClause)

This method returns a Vector of NetNodes to a given query string

Parameters:

sqlClause - The where clause for the query string.

getNetNodeCount

public static int getNetNodeCount(java.lang.String tables,
                                  java.lang.String sqlClause)

This method returns a number of NetNodes to a given query string.

Parameters:

tables - The table names.

sqlClause - The where clause for the query string.

Returns:

The number of nodes.

getNetNodeCount

public static int getNetNodeCount(java.lang.String sqlClause)

This method returns a number of NetNodes to a given query string.

Parameters:

sqlClause - The where clause for the query string.

Returns:

The number of nodes.

clean

public static void clean()

stores the cached NetNodes and removes empty entries from the cache.

addItem

protected void addItem(java.lang.Object o)

notifyObservers

public void notifyObservers()

Overrides:

notifyObservers in class java.util.Observable