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 [dmsmith555 at yahoo dot com]

See Also:

for license details.
The copyright to this program is held by it's authors.

Field Summary

private static String	DEFAULT The string for default implementations
static String	EXTENSION_PLUGIN Extension for properties files
private static Logger	log The log stream

Constructor Summary

private

PluginUtil() Prevent instantiation

Method Summary

static Object	getImplementation(Class clazz) Get and instantiate the preferred implementor of some interface or abstract class.
static Class	getImplementor(Class clazz) Get the preferred implementor of some interface or abstract class.
static Class[]	getImplementors(Class clazz) Get the known implementors of some interface or abstract class.
static Map	getImplementorsMap(Class clazz) Get a map of known implementors of some interface or abstract class.
static Properties	getPlugin(Class 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 Logger log

The log stream

Constructor Detail

PluginUtil

private PluginUtil()

Prevent instantiation

Method Detail

getImplementors

public static Class[] getImplementors(Class 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.

Parameters:

clazz - The class or interface to find implementors of.

Returns:

The list of implementing classes.

getImplementorsMap

public static Map getImplementorsMap(Class 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.

Parameters:

clazz - The class or interface to find implementors of.

Returns:

The map of implementing classes.

See Also:

getImplementors(Class)

getImplementor

public static Class getImplementor(Class 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.

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 Object getImplementation(Class clazz)
                                throws MalformedURLException,
                                       ClassCastException,
                                       IOException,
                                       ClassNotFoundException,
                                       InstantiationException,
                                       IllegalAccessException

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

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 Properties getPlugin(Class clazz)
                            throws IOException

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

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