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Eclipse Platform Release 3.0 |
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java.lang.Objectorg.eclipse.core.runtime.Plugin
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 desireable
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.
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 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.
|
static String |
PREFERENCES_DEFAULT_OVERRIDE_FILE_NAME
|
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)
Returns a URL for the given path. |
URL |
find(IPath path,
Map override)
Returns a URL for the given path. |
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()
Returns the preference store for this plug-in. |
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() { MyPlugin.getPlugin().getPluginPreferences().setDefault(key, value); } } |
void |
internalInitializeDefaultPluginPreferences()
Internal method. |
boolean |
isDebugging()
Returns whether this plug-in is in debug mode. |
InputStream |
openStream(IPath file)
Returns an input stream for the specified file. |
InputStream |
openStream(IPath file,
boolean localized)
Returns an input stream for the specified file. |
void |
savePluginPreferences()
Saves preferences settings for this plug-in. |
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 |
public static final String PLUGIN_PREFERENCE_SCOPE
public static final String PREFERENCES_DEFAULT_OVERRIDE_BASE_NAME
"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.
public static final String PREFERENCES_DEFAULT_OVERRIDE_FILE_NAME
Constructor Detail |
public Plugin()
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.
public Plugin(IPluginDescriptor descriptor)
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.
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.
descriptor
- the plug-in descriptorgetDescriptor()
Method Detail |
public final URL find(IPath path)
null
if the URL
could not be computed or created.
path
- path relative to plug-in installation location
null
public final URL find(IPath path, Map override)
null
if the URL
could not be computed or created.
path
- file path relative to plug-in installation locationoverride
- 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.
null
public final IPluginDescriptor getDescriptor()
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.
public final ILog getLog()
public final IPath getStateLocation() throws IllegalStateException
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.
IllegalStateException
public final Preferences getPluginPreferences()
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.
savePluginPreferences()
,
Preferences.setValue(String, String)
,
Preferences.setToDefault(String)
public final void savePluginPreferences()
Plug-in preferences are not saved automatically on plug-in shutdown.
Preferences.store(OutputStream, String)
,
Preferences.needsSaving()
protected void initializeDefaultPluginPreferences()
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() { MyPlugin.getPlugin().getPluginPreferences().setDefault(key, value); } }
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).
public final void internalInitializeDefaultPluginPreferences()
public boolean isDebugging()
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.
public final InputStream openStream(IPath file) throws IOException
file
- path relative to plug-in installation location
IOException
- if the given path cannot be found in this plug-inopenStream(IPath,boolean)
public final InputStream openStream(IPath file, boolean localized) throws IOException
The caller must close the returned stream when done.
file
- path relative to plug-in installation locationlocalized
- true
for the localized version
of the file, and false
for the file exactly
as specified
IOException
- if the given path cannot be found in this plug-inpublic void setDebugging(boolean value)
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.
value
- whether or not this plug-in is in debug modepublic void shutdown() throws CoreException
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.
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.
CoreException
- if this method fails to shut down
this plug-inpublic void startup() throws CoreException
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.
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.
CoreException
- if this plug-in did not start up properlypublic String toString()
public void start(BundleContext context) throws Exception
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.
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.
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.
Clients must never explicitly call this method.
start
in interface BundleActivator
context
- the bundle context for this plug-in
Exception
- if this plug-in did not start up properlypublic void stop(BundleContext context) throws Exception
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, as this method will be invoked in the event of a failure during startup.
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.
Clients must never explicitly call this method.
stop
in interface BundleActivator
context
- the bundle context for this plug-in
Exception
- if this method fails to shut down this plug-inpublic final Bundle getBundle()
|
Eclipse Platform Release 3.0 |
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Guidelines for using Eclipse APIs.
Copyright (c) IBM Corp. and others 2000, 2004. All rights reserved.