org.crosswire.common.util

Class PluginUtil

java.lang.Object

org.crosswire.common.util.PluginUtil

public final class PluginUtil
extends Object

A plugin maps one or more implementations to an interface or abstract class via a properties file whose suffix is "plugin". When there is more than one implementation, one is marked as a default.

Author:

DM Smith

See Also:

The GNU Lesser General Public License for details.

Field Summary

Fields

Modifier and Type	Field and Description
private static String	DEFAULT The string for default implementations
static String	EXTENSION_PLUGIN Extension for properties files
private static org.slf4j.Logger	log The log stream

Constructor Summary

Constructors

Modifier	Constructor and Description
private	PluginUtil() Prevent instantiation

Method Summary

Methods

Modifier and Type	Method and Description
static <T> T	getImplementation(Class<T> clazz) Get and instantiate the preferred implementor of some interface or abstract class.
static <T> Class<T>	getImplementor(Class<T> clazz) Get the preferred implementor of some interface or abstract class.
static <T> Class<T>[]	getImplementors(Class<T> clazz) Get the known implementors of some interface or abstract class.
static <T> Map<String,Class<T>>	getImplementorsMap(Class<T> clazz) Get a map of known implementors of some interface or abstract class.
static <T> PropertyMap	getPlugin(Class<T> clazz) Get and load a plugin file by looking it up as a resource.

Methods inherited from class java.lang.Object

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

Field Detail

EXTENSION_PLUGIN

public static final String EXTENSION_PLUGIN

Extension for properties files

See Also:

Constant Field Values

DEFAULT

private static final String DEFAULT

The string for default implementations

See Also:

Constant Field Values

log

private static final org.slf4j.Logger log

The log stream

Constructor Detail

PluginUtil

private PluginUtil()

Prevent instantiation

Method Detail

getImplementors

public static <T> Class<T>[] getImplementors(Class<T> clazz)

Get the known implementors of some interface or abstract class. This is currently done by looking up a plugin file by the name of the given class, and assuming that values are implementors of said class. Those that are not are warned, but ignored.

Type Parameters:

T - the implementor's type

Parameters:

clazz - The class or interface to find implementors of.

Returns:

The list of implementing classes.

getImplementorsMap

public static <T> Map<String,Class<T>> getImplementorsMap(Class<T> clazz)

Get a map of known implementors of some interface or abstract class. This is currently done by looking up a plugins file by the name of the given class, and assuming that values are implementors of said class. Those that are not are warned, but ignored. The reply is in the form of a map of keys=strings, and values=classes in case you need to get at the names given to the classes in the plugin file.

Type Parameters:

T - the implementor's type

Parameters:

clazz - The class or interface to find implementors of.

Returns:

The map of implementing classes.

See Also:

getImplementors(Class)

getImplementor

public static <T> Class<T> getImplementor(Class<T> clazz)
                               throws IOException,
                                      ClassNotFoundException,
                                      ClassCastException

Get the preferred implementor of some interface or abstract class. This is currently done by looking up a plugins file by the name of the given class, and assuming that the "default" key is an implementation of said class. Warnings are given otherwise.

Type Parameters:

T - the implementor's type

Parameters:

clazz - The class or interface to find an implementation of.

Returns:

The configured implementing class.

Throws:

MalformedURLException - if the plugin file can not be found

IOException - if there is a problem reading the found file

ClassNotFoundException - if the read contents are not found

ClassCastException - if the read contents are not valid

See Also:

getImplementors(Class)

getImplementation

public static <T> T getImplementation(Class<T> clazz)
                           throws MalformedURLException,
                                  ClassCastException,
                                  IOException,
                                  ClassNotFoundException,
                                  InstantiationException,
                                  IllegalAccessException

Get and instantiate the preferred implementor of some interface or abstract class.

Type Parameters:

T - the implementor's type

Parameters:

clazz - The class or interface to find an implementation of.

Returns:

The configured implementing class.

Throws:

MalformedURLException - if the plugin file can not be found

IOException - if there is a problem reading the found file

ClassNotFoundException - if the read contents are not found

ClassCastException - if the read contents are not valid

InstantiationException - if the new object can not be instantiated

IllegalAccessException - if the new object can not be instantiated

See Also:

getImplementors(Class)

getPlugin

public static <T> PropertyMap getPlugin(Class<T> clazz)
                             throws IOException

Get and load a plugin file by looking it up as a resource.

Type Parameters:

T - the implementor's type

Parameters:

clazz - The name of the desired resource

Returns:

The found and loaded plugin file

Throws:

IOException - if the resource can not be loaded

MissingResourceException - if the resource can not be found