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Eclipse Platform
Release 3.5

org.eclipse.core.runtime
Class Plugin

java.lang.Object
  extended by 
org.eclipse.core.runtime.Plugin
All Implemented Interfaces:
BundleActivator
Direct Known Subclasses:
AbstractUIPlugin, AntCorePlugin, DebugPlugin, ResourcesPlugin, VariablesPlugin

public abstract class Plugin
extends Object
implements BundleActivator

The abstract superclass of all plug-in runtime class implementations. A plug-in subclasses this class and overrides the appropriate life cycle methods in order to react to the life cycle requests automatically issued by the platform. For compatibility reasons, the methods called for those life cycle events vary, please see the "Constructors and life cycle methods" section below.

Conceptually, the plug-in runtime class represents the entire plug-in rather than an implementation of any one particular extension the plug-in declares. A plug-in is not required to explicitly specify a plug-in runtime class; if none is specified, the plug-in will be given a default plug-in runtime object that ignores all life cycle requests (it still provides access to the corresponding plug-in descriptor).

In the case of more complex plug-ins, it may be desirable to define a concrete subclass of Plugin. However, just subclassing Plugin is not sufficient. The name of the class must be explicitly configured in the plug-in's manifest (plugin.xml) file with the class attribute of the <plugin> element markup.

Instances of plug-in runtime classes are automatically created by the platform in the course of plug-in activation. For compatibility reasons, the constructor used to create plug-in instances varies, please see the "Constructors and life cycle methods" section below.

The concept of bundles underlies plug-ins. However it is safe to regard plug-ins and bundles as synonyms.

Clients must never explicitly instantiate a plug-in runtime class.

A typical implementation pattern for plug-in runtime classes is to provide a static convenience method to gain access to a plug-in's runtime object. This way, code in other parts of the plug-in implementation without direct access to the plug-in runtime object can easily obtain a reference to it, and thence to any plug-in-wide resources recorded on it. An example for Eclipse 3.0 follows:

     package myplugin;
     public class MyPluginClass extends Plugin {
         private static MyPluginClass instance;

         public static MyPluginClass getInstance() { return instance; }

         public void MyPluginClass() {
             super();
             instance = this;
             // ... other initialization
         }
         // ... other methods
     }
 
In the above example, a call to MyPluginClass.getInstance() will always return an initialized instance of MyPluginClass.

Constructors and life cycle methods

If the plugin.xml of a plug-in indicates <?eclipse version="3.0"?> and its prerequisite list includes org.eclipse.core.runtime, the default constructor of the plug-in class is used and start(BundleContext) and stop(BundleContext) are called as life cycle methods.

If the plugin.xml of a plug-in indicates <?eclipse version="3.0"?> and its prerequisite list includes org.eclipse.core.runtime.compatibility, the Plugin(IPluginDescriptor) constructor is used and startup() and shutdown() are called as life cycle methods. Note that in this situation, start() is called before startup() and stop() is called after shutdown.

If the plugin.xml of your plug-in does not indicate <?eclipse version="3.0"?> it is therefore not a 3.0 plug-in. Consequently the Plugin(IPluginDescriptor) is used and startup() and shutdown() are called as life cycle methods.

Since Eclipse 3.0 APIs of the Plugin class can be called only when the Plugin is in an active state, i.e., after it was started up and before it is shutdown. In particular, it means that Plugin APIs should not be called from overrides of Plugin().


Field Summary
static  String PLUGIN_PREFERENCE_SCOPE
          String constant used for the default scope name for legacy Eclipse plug-in preferences.
static  String PREFERENCES_DEFAULT_OVERRIDE_BASE_NAME
          The base name (value "preferences") for the file which is used for overriding default preference values.
static  String PREFERENCES_DEFAULT_OVERRIDE_FILE_NAME
          The name of the file (value "preferences.ini") in a plug-in's (read-only) directory that, when present, contains values that override the normal default values for this plug-in's preferences.
 
Constructor Summary
Plugin ()
          Creates a new plug-in runtime object.
Plugin ( IPluginDescriptor descriptor)
          Deprecated. In Eclipse 3.0 this constructor has been replaced by Plugin(). Implementations of MyPlugin(IPluginDescriptor descriptor) should be changed to MyPlugin() and call super() instead of super(descriptor). The MyPlugin(IPluginDescriptor descriptor) constructor is called only for plug-ins which explicitly require the org.eclipse.core.runtime.compatibility plug-in.
 
Method Summary
  URL find ( IPath path)
          Deprecated. use FileLocator.find(Bundle, IPath, Map)
  URL find ( IPath path, Map override)
          Deprecated. use FileLocator.find(Bundle, IPath, Map)
  Bundle getBundle ()
          Returns the bundle associated with this plug-in.
  IPluginDescriptor getDescriptor ()
          Deprecated.  IPluginDescriptor was refactored in Eclipse 3.0. The getDescriptor() method may only be called by plug-ins which explicitly require the org.eclipse.core.runtime.compatibility plug-in. See the comments on IPluginDescriptor and its methods for details.
  ILog getLog ()
          Returns the log for this plug-in.
  Preferences getPluginPreferences ()
          Deprecated. Replaced by IEclipsePreferences. Preferences are now stored according to scopes in the IPreferencesService. The return value of this method corresponds to a combination of the InstanceScope and the DefaultScope. To set preferences for your plug-in, use new InstanceScope().getNode(<&yourPluginId>). To set default preferences for your plug-in, use new DefaultScope().getNode(<yourPluginId>). To lookup an integer preference value for your plug-in, use Platform.getPreferencesService().getInt(<yourPluginId>, <preferenceKey>, <defaultValue>, null). Similar methods exist on IPreferencesService for obtaining other kinds of preference values (strings, booleans, etc).
  IPath getStateLocation ()
          Returns the location in the local file system of the plug-in state area for this plug-in.
protected  void initializeDefaultPluginPreferences ()
          Deprecated. This method has been refactored in the new preference mechanism to handle the case where the runtime compatibility layer does not exist. The contents of this method should be moved to the method named initializeDefaultPreferences in a separate subclass of AbstractPreferenceInitializer. This class should be contributed via the org.eclipse.core.runtime.preferences extension point.
        <extension point=&quo;org.eclipse.core.runtime.preferences&quo;>
                        <initializer class=&quo;com.example.MyPreferenceInitializer&quo;/>
                </extension>
                ...
                package com.example;
                public class MyPreferenceInitializer extends AbstractPreferenceInitializer {
                        public MyPreferenceInitializer() {
                                super();
                        }
                        public void initializeDefaultPreferences() {
                                Preferences node = new DefaultScope().getNode("my.plugin.id");
                                node.put(key, value);
                        }
                }
 
 void internalInitializeDefaultPluginPreferences ()
          Deprecated.   
 boolean isDebugging ()
          Returns whether this plug-in is in debug mode.
  InputStream openStream ( IPath file)
          Deprecated. use FileLocator.openStream(Bundle, IPath, boolean)
  InputStream openStream ( IPath file, boolean substituteArgs)
          Deprecated. use FileLocator.openStream(Bundle, IPath, boolean)
 void savePluginPreferences ()
          Deprecated. Replaced by InstanceScope.getNode(<bundleId>).flush()
 void setDebugging (boolean value)
          Sets whether this plug-in is in debug mode.
 void shutdown ()
          Deprecated. In Eclipse 3.0 this method has been replaced by stop(BundleContext context). Implementations of shutdown() should be changed to override stop(BundleContext context) and call super.stop(context) instead of super.shutdown(). The shutdown() method is called only for plug-ins which explicitly require the org.eclipse.core.runtime.compatibility plug-in.
 void start ( BundleContext context)
          Starts up this plug-in.
 void startup ()
          Deprecated. In Eclipse 3.0 this method has been replaced by start(BundleContext context). Implementations of startup() should be changed to extend start(BundleContext context) and call super.start(context) instead of super.startup(). The startup() method is called only for plug-ins which explicitly require the org.eclipse.core.runtime.compatibility plug-in.
 void stop ( BundleContext context)
          Stops this plug-in.
  String toString ()
          Returns a string representation of the plug-in, suitable for debugging purposes only.
 
Methods inherited from class java.lang. Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

PLUGIN_PREFERENCE_SCOPE

public static final 
String PLUGIN_PREFERENCE_SCOPE
String constant used for the default scope name for legacy Eclipse plug-in preferences. The value of PLUGIN_PREFERENCE_SCOPE should match the InstanceScope's variable SCOPE from org.eclipse.core.runtime.preferences. The value is copied in this file to prevent unnecessary activation of the Preferences plugin on startup.

Since:
3.0
See Also:
Constant Field Values

PREFERENCES_DEFAULT_OVERRIDE_BASE_NAME

public static final 
String PREFERENCES_DEFAULT_OVERRIDE_BASE_NAME
The base name (value "preferences") for the file which is used for overriding default preference values.

Since:
2.0
See Also:
PREFERENCES_DEFAULT_OVERRIDE_FILE_NAME, Constant Field Values

PREFERENCES_DEFAULT_OVERRIDE_FILE_NAME

public static final 
String PREFERENCES_DEFAULT_OVERRIDE_FILE_NAME
The name of the file (value "preferences.ini") in a plug-in's (read-only) directory that, when present, contains values that override the normal default values for this plug-in's preferences.

The format of the file is as per java.io.Properties where the keys are property names and values are strings.

Since:
2.0
See Also:
Constant Field Values
Constructor Detail

Plugin

public Plugin()
Creates a new plug-in runtime object. This method is called by the platform if this class is used as a BundleActivator. This method is not needed/used if this plug-in requires the org.eclipse.core.runtime.compatibility plug-in. Subclasses of Plugin must call this method first in their constructors. The resultant instance is not managed by the runtime and so should be remembered by the client (typically using a Singleton pattern). Clients must never explicitly call this method.

Note: The class loader typically has monitors acquired during invocation of this method. It is strongly recommended that this method avoid synchronized blocks or other thread locking mechanisms, as this would lead to deadlock vulnerability.

Since:
3.0

Plugin

public Plugin(
IPluginDescriptor descriptor)
Deprecated. In Eclipse 3.0 this constructor has been replaced by Plugin(). Implementations of MyPlugin(IPluginDescriptor descriptor) should be changed to MyPlugin() and call super() instead of super(descriptor). The MyPlugin(IPluginDescriptor descriptor) constructor is called only for plug-ins which explicitly require the org.eclipse.core.runtime.compatibility plug-in.

Creates a new plug-in runtime object for the given plug-in descriptor.

Instances of plug-in runtime classes are automatically created by the platform in the course of plug-in activation. Clients must never explicitly call this method.

Note: The class loader typically has monitors acquired during invocation of this method. It is strongly recommended that this method avoid synchronized blocks or other thread locking mechanisms, as this would lead to deadlock vulnerability.

Parameters:
descriptor - the plug-in descriptor
See Also:
getDescriptor()
Method Detail

find

public final 
URL find(
IPath path)
Deprecated. use FileLocator.find(Bundle, IPath, Map)

Returns a URL for the given path. Returns null if the URL could not be computed or created.

Parameters:
path - path relative to plug-in installation location
Returns:
a URL for the given path or null

find

public final 
URL find(
IPath path,
                      
Map override)
Deprecated. use FileLocator.find(Bundle, IPath, Map)

Returns a URL for the given path. Returns null if the URL could not be computed or created.

Parameters:
path - file path relative to plug-in installation location
override - map of override substitution arguments to be used for any $arg$ path elements. The map keys correspond to the substitution arguments (eg. "$nl$" or "$os$"). The resulting values must be of type java.lang.String. If the map is null, or does not contain the required substitution argument, the default is used.
Returns:
a URL for the given path or null

getDescriptor

public final 
IPluginDescriptor getDescriptor()
Deprecated.  IPluginDescriptor was refactored in Eclipse 3.0. The getDescriptor() method may only be called by plug-ins which explicitly require the org.eclipse.core.runtime.compatibility plug-in. See the comments on IPluginDescriptor and its methods for details.

Returns the plug-in descriptor for this plug-in runtime object.

Returns:
the plug-in descriptor for this plug-in runtime object

getLog

public final 
ILog getLog()
Returns the log for this plug-in. If no such log exists, one is created.

Returns:
the log for this plug-in XXX change this into a LogMgr service that would keep track of the map. See if it can be a service factory.

getStateLocation

public final 
IPath getStateLocation()
                             throws 
IllegalStateException
Returns the location in the local file system of the plug-in state area for this plug-in. If the plug-in state area did not exist prior to this call, it is created.

The plug-in state area is a file directory within the platform's metadata area where a plug-in is free to create files. The content and structure of this area is defined by the plug-in, and the particular plug-in is solely responsible for any files it puts there. It is recommended for plug-in preference settings and other configuration parameters.

Returns:
a local file system path XXX Investigate the usage of a service factory (see also platform.getStateLocation)
Throws:
IllegalStateException, - when the system is running with no data area (-data @none), or when a data area has not been set yet.
IllegalStateException

getPluginPreferences

public final 
Preferences getPluginPreferences()
Deprecated. Replaced by IEclipsePreferences. Preferences are now stored according to scopes in the IPreferencesService. The return value of this method corresponds to a combination of the InstanceScope and the DefaultScope. To set preferences for your plug-in, use new InstanceScope().getNode(<&yourPluginId>). To set default preferences for your plug-in, use new DefaultScope().getNode(<yourPluginId>). To lookup an integer preference value for your plug-in, use Platform.getPreferencesService().getInt(<yourPluginId>, <preferenceKey>, <defaultValue>, null). Similar methods exist on IPreferencesService for obtaining other kinds of preference values (strings, booleans, etc).

Returns the preference store for this plug-in.

Note that if an error occurs reading the preference store from disk, an empty preference store is quietly created, initialized with defaults, and returned.

Calling this method may cause the preference store to be created and initialized. Subclasses which reimplement the initializeDefaultPluginPreferences method have this opportunity to initialize preference default values, just prior to processing override default values imposed externally to this plug-in (specified for the product, or at platform start up).

After settings in the preference store are changed (for example, with Preferences.setValue or setToDefault), savePluginPreferences should be called to store the changed values back to disk. Otherwise the changes will be lost on plug-in shutdown.

Returns:
the preference store
Since:
2.0
See Also:
savePluginPreferences(), Preferences.setValue(String, String), Preferences.setToDefault(String)

savePluginPreferences

public final void savePluginPreferences()
Deprecated. Replaced by InstanceScope.getNode(<bundleId>).flush()

Saves preferences settings for this plug-in. Does nothing if the preference store does not need saving.

Plug-in preferences are not saved automatically on plug-in shutdown.

Since:
2.0
See Also:
Preferences.store(OutputStream, String), Preferences.needsSaving()

initializeDefaultPluginPreferences

protected void initializeDefaultPluginPreferences()
Deprecated. This method has been refactored in the new preference mechanism to handle the case where the runtime compatibility layer does not exist. The contents of this method should be moved to the method named initializeDefaultPreferences in a separate subclass of AbstractPreferenceInitializer. This class should be contributed via the org.eclipse.core.runtime.preferences extension point.
        <extension point=&quo;org.eclipse.core.runtime.preferences&quo;>
                        <initializer class=&quo;com.example.MyPreferenceInitializer&quo;/>
                </extension>
                ...
                package com.example;
                public class MyPreferenceInitializer extends AbstractPreferenceInitializer {
                        public MyPreferenceInitializer() {
                                super();
                        }
                        public void initializeDefaultPreferences() {
                                Preferences node = new DefaultScope().getNode("my.plugin.id");
                                node.put(key, value);
                        }
                }
 

Initializes the default preferences settings for this plug-in.

This method is called sometime after the preference store for this plug-in is created. Default values are never stored in preference stores; they must be filled in each time. This method provides the opportunity to initialize the default values.

The default implementation of this method does nothing. A subclass that needs to set default values for its preferences must reimplement this method. Default values set at a later point will override any default override settings supplied from outside the plug-in (product configuration or platform start up).

Since:
2.0

internalInitializeDefaultPluginPreferences

public final void internalInitializeDefaultPluginPreferences()
Deprecated. 

Internal method. This method is a hook for initialization of default preference values. It should not be called by clients.

Since:
3.0

isDebugging

public boolean isDebugging()
Returns whether this plug-in is in debug mode. By default plug-ins are not in debug mode. A plug-in can put itself into debug mode or the user can set an execution option to do so.

Note that the plug-in's debug flag is initialized when the plug-in is started. The result of calling this method before the plug-in has started is unspecified.

Returns:
whether this plug-in is in debug mode XXX deprecate use the service and cache as needed

openStream

public final 
InputStream openStream(
IPath file)
                             throws 
IOException
Deprecated. use FileLocator.openStream(Bundle, IPath, boolean)

Returns an input stream for the specified file. The file path must be specified relative this the plug-in's installation location.

Parameters:
file - path relative to plug-in installation location
Returns:
an input stream
Throws:
IOException - if the given path cannot be found in this plug-in
See Also:
openStream(IPath,boolean)

openStream

public final 
InputStream openStream(
IPath file,
                                    boolean substituteArgs)
                             throws 
IOException
Deprecated. use FileLocator.openStream(Bundle, IPath, boolean)

Returns an input stream for the specified file. The file path must be specified relative to this plug-in's installation location. Optionally, the path specified may contain $arg$ path elements that can be used as substitution arguments. If this option is used then the $arg$ path elements are processed in the same way as find(IPath, Map).

The caller must close the returned stream when done.

Parameters:
file - path relative to plug-in installation location
substituteArgs - true to process substitution arguments, and false for the file exactly as specified without processing any substitution arguments.
Returns:
an input stream
Throws:
IOException - if the given path cannot be found in this plug-in

setDebugging

public void setDebugging(boolean value)
Sets whether this plug-in is in debug mode. By default plug-ins are not in debug mode. A plug-in can put itself into debug mode or the user can set a debug option to do so.

Note that the plug-in's debug flag is initialized when the plug-in is started. The result of calling this method before the plug-in has started is unspecified.

Parameters:
value - whether or not this plug-in is in debug mode XXX deprecate use the service and cache as needed

shutdown

public void shutdown()
              throws 
CoreException
Deprecated. In Eclipse 3.0 this method has been replaced by stop(BundleContext context). Implementations of shutdown() should be changed to override stop(BundleContext context) and call super.stop(context) instead of super.shutdown(). The shutdown() method is called only for plug-ins which explicitly require the org.eclipse.core.runtime.compatibility plug-in.

Shuts down this plug-in and discards all plug-in state.

This method should be re-implemented in subclasses that need to do something when the plug-in is shut down. Implementors should call the inherited method to ensure that any system requirements can be met.

Plug-in shutdown code should be robust. In particular, this method should always make an effort to shut down the plug-in. Furthermore, the code should not assume that the plug-in was started successfully, as this method will be invoked in the event of a failure during startup.

Note 1: If a plug-in has been started, this method will be automatically invoked by the platform when the platform is shut down.

Note 2: This method is intended to perform simple termination of the plug-in environment. The platform may terminate invocations that do not complete in a timely fashion.

Clients must never explicitly call this method.

Throws:
CoreException - if this method fails to shut down this plug-in

startup

public void startup()
             throws 
CoreException
Deprecated. In Eclipse 3.0 this method has been replaced by start(BundleContext context). Implementations of startup() should be changed to extend start(BundleContext context) and call super.start(context) instead of super.startup(). The startup() method is called only for plug-ins which explicitly require the org.eclipse.core.runtime.compatibility plug-in.

Starts up this plug-in.

This method should be overridden in subclasses that need to do something when this plug-in is started. Implementors should call the inherited method to ensure that any system requirements can be met.

If this method throws an exception, it is taken as an indication that plug-in initialization has failed; as a result, the plug-in will not be activated; moreover, the plug-in will be marked as disabled and ineligible for activation for the duration.

Plug-in startup code should be robust. In the event of a startup failure, the plug-in's shutdown method will be invoked automatically, in an attempt to close open files, etc.

Note 1: This method is automatically invoked by the platform the first time any code in the plug-in is executed.

Note 2: This method is intended to perform simple initialization of the plug-in environment. The platform may terminate initializers that do not complete in a timely fashion.

Note 3: The class loader typically has monitors acquired during invocation of this method. It is strongly recommended that this method avoid synchronized blocks or other thread locking mechanisms, as this would lead to deadlock vulnerability.

Clients must never explicitly call this method.

Throws:
CoreException - if this plug-in did not start up properly

toString

public 
String toString()
Returns a string representation of the plug-in, suitable for debugging purposes only.

Overrides:
toString in class Object

start

public void start(
BundleContext context)
           throws 
Exception
Starts up this plug-in.

This method should be overridden in subclasses that need to do something when this plug-in is started. Implementors should call the inherited method at the first possible point to ensure that any system requirements can be met.

If this method throws an exception, it is taken as an indication that plug-in initialization has failed; as a result, the plug-in will not be activated; moreover, the plug-in will be marked as disabled and ineligible for activation for the duration.

Note 1: This method is automatically invoked by the platform the first time any code in the plug-in is executed.

Note 2: This method is intended to perform simple initialization of the plug-in environment. The platform may terminate initializers that do not complete in a timely fashion.

Note 3: The class loader typically has monitors acquired during invocation of this method. It is strongly recommended that this method avoid synchronized blocks or other thread locking mechanisms, as this would lead to deadlock vulnerability.

Note 4: The supplied bundle context represents the plug-in to the OSGi framework. For security reasons, it is strongly recommended that this object should not be divulged.

Note 5: This method and the stop(BundleContext) may be called from separate threads, but the OSGi framework ensures that both methods will not be called simultaneously.

Clients must never explicitly call this method.

Specified by:
start in interface BundleActivator
Parameters:
context - the bundle context for this plug-in
Throws:
Exception - if this plug-in did not start up properly
Since:
3.0

stop

public void stop(
BundleContext context)
          throws 
Exception
Stops this plug-in.

This method should be re-implemented in subclasses that need to do something when the plug-in is shut down. Implementors should call the inherited method as late as possible to ensure that any system requirements can be met.

Plug-in shutdown code should be robust. In particular, this method should always make an effort to shut down the plug-in. Furthermore, the code should not assume that the plug-in was started successfully.

Note 1: If a plug-in has been automatically started, this method will be automatically invoked by the platform when the platform is shut down.

Note 2: This method is intended to perform simple termination of the plug-in environment. The platform may terminate invocations that do not complete in a timely fashion.

Note 3: The supplied bundle context represents the plug-in to the OSGi framework. For security reasons, it is strongly recommended that this object should not be divulged.

Note 4: This method and the start(BundleContext) may be called from separate threads, but the OSGi framework ensures that both methods will not be called simultaneously.

Clients must never explicitly call this method.

Specified by:
stop in interface BundleActivator
Parameters:
context - the bundle context for this plug-in
Throws:
Exception - if this method fails to shut down this plug-in
Since:
3.0

getBundle

public final 
Bundle getBundle()
Returns the bundle associated with this plug-in.

Returns:
the associated bundle
Since:
3.0

Eclipse Platform
Release 3.5

Guidelines for using Eclipse APIs.

Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.


 
 
  Published under the terms of the Eclipse Public License Version 1.0 ("EPL") Design by Interspire