Package org.apache.nutch.plugin

Class Extension

java.lang.Object

org.apache.nutch.plugin.Extension

public class Extension
extends Object

An Extension is a kind of listener descriptor that will be installed on a concrete ExtensionPoint that acts as kind of Publisher.

Constructor Summary

Constructors

Constructor	Description
Extension(PluginDescriptor pDescriptor, String pExtensionPoint, String pId, String pExtensionClass, Configuration conf, PluginRepository pluginRepository)

Method Summary

Modifier and Type	Method	Description
void	addAttribute(String pKey, String pValue)	Adds a attribute and is only used until model creation at plugin system start up.
String	getAttribute(String pKey)	Returns a attribute value, that is setuped in the manifest file and is definied by the extension point xml schema.
String	getClazz()	Returns the full class name of the extension point implementation
PluginDescriptor	getDescriptor()	Get the plugin descriptor.
Object	getExtensionInstance()	Return an instance of the extension implementation.
String	getId()	Return the unique id of the extension.
String	getTargetPoint()	Get target point
void	setClazz(String extensionClazz)	Sets the Class that implement the concret extension and is only used until model creation at system start up.
void	setDescriptor(PluginDescriptor pDescriptor)	Sets the plugin descriptor and is only used until model creation at system start up.
void	setId(String extensionID)	Sets the unique extension Id and is only used until model creation at system start up.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Details

Extension

public Extension(PluginDescriptor pDescriptor,
 String pExtensionPoint,
 String pId,
 String pExtensionClass,
 Configuration conf,
 PluginRepository pluginRepository)

Parameters:

pDescriptor - a plugin descriptor

pExtensionPoint - an extension point

pId - an unique id of the plugin

pExtensionClass - the class extending the extension point

conf - a populated Configuration

pluginRepository - a PluginRepository containing all plugin artifacts

Method Details

getAttribute

public String getAttribute(String pKey)

Returns a attribute value, that is setuped in the manifest file and is definied by the extension point xml schema.

Parameters:

pKey - a key

Returns:

String a value

getClazz

public String getClazz()

Returns the full class name of the extension point implementation

Returns:

String

getId

public String getId()

Return the unique id of the extension.

Returns:

String

addAttribute

public void addAttribute(String pKey,
 String pValue)

Adds a attribute and is only used until model creation at plugin system start up.

Parameters:

pKey - a key

pValue - a value

setClazz

public void setClazz(String extensionClazz)

Sets the Class that implement the concret extension and is only used until model creation at system start up.

Parameters:

extensionClazz - The extensionClasname to set

setId

public void setId(String extensionID)

Sets the unique extension Id and is only used until model creation at system start up.

Parameters:

extensionID - The extensionID to set

getTargetPoint

public String getTargetPoint()

Get target point

Returns:

the Id of the extension point, that is implemented by this extension.

getExtensionInstance

public Object getExtensionInstance()
                            throws PluginRuntimeException

Return an instance of the extension implementation. Before we create a extension instance we startup the plugin if it is not already done. The plugin instance and the extension instance use the same PluginClassLoader. Each Plugin uses its own classloader. The PluginClassLoader knows only its own plugin runtime libraries defined in the plugin.xml manifest file and exported libraries of the dependent plugins.

Returns:

Object An instance of the extension implementation

Throws:

PluginRuntimeException - if there is a fatal runtime error

getDescriptor

public PluginDescriptor getDescriptor()

Get the plugin descriptor.

Returns:

PluginDescriptor

setDescriptor

public void setDescriptor(PluginDescriptor pDescriptor)

Sets the plugin descriptor and is only used until model creation at system start up.

Parameters:

pDescriptor - a instantiated PluginDescriptor

toString

public String toString()

Overrides:

toString in class Object