be.atbash.util.reflection

Class ClassUtils

java.lang.Object

be.atbash.util.reflection.ClassUtils

public final class ClassUtils
extends Object

Utility class used to conveniently interact with Classes, such as acquiring them from the application ClassLoaders and instantiating Objects from them.

Class original found in Apache Shiro but modified for enhanced functionality.

Method Summary

Modifier and Type	Method and Description
static Class	forName(String fqcn) Attempts to load the specified class name from the current thread's context class loader, then the current ClassLoader (ClassUtils.class.getClassLoader()), then the system/application ClassLoader (ClassLoader.getSystemClassLoader(), in that order.
static InputStream	getResourceAsStream(String name) Returns the specified resource by checking the current thread's context class loader, then the current ClassLoader (ClassUtils.class.getClassLoader()), then the system/application ClassLoader (ClassLoader.getSystemClassLoader(), in that order, using getResourceAsStream(name).
static boolean	isAvailable(String fullyQualifiedClassName) Checks if the fullyQualifiedClassName is available on any classloader.
static <T> T	newInstance(Class clazz) Creates an instance of the class using the no-arg constructor.
static <T> T	newInstance(Class clazz, Object... args) Creates an instance of the class with a constructor matching the arguments.
static <T> T	newInstance(String fqcn) Creates an instance of the class where it is searched by the algorithm described at the forName(String) method using the no-arg constructor.
static <T> T	newInstance(String fqcn, Object... args) Creates an instance of the class where it is searched by the algorithm described at the forName(String) method with a constructor matching the arguments.

Methods inherited from class java.lang.Object

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

Method Detail

getResourceAsStream

public static InputStream getResourceAsStream(String name)

Returns the specified resource by checking the current thread's context class loader, then the current ClassLoader (ClassUtils.class.getClassLoader()), then the system/application ClassLoader (ClassLoader.getSystemClassLoader(), in that order, using getResourceAsStream(name).

Parameters:

name - the name of the resource to acquire from the classloader(s).

Returns:

the InputStream of the resource found, or null if the resource cannot be found from any of the three mentioned ClassLoaders.

forName

public static Class forName(String fqcn)

Attempts to load the specified class name from the current thread's context class loader, then the current ClassLoader (ClassUtils.class.getClassLoader()), then the system/application ClassLoader (ClassLoader.getSystemClassLoader(), in that order. If any of them cannot locate the specified class, an UnknownClassException is thrown (our RuntimeException equivalent of the JRE's ClassNotFoundException.

Parameters:

fqcn - the fully qualified class name to load

Returns:

the located class

Throws:

UnknownClassException - if the class cannot be found.

isAvailable

public static boolean isAvailable(String fullyQualifiedClassName)

Checks if the fullyQualifiedClassName is available on any classloader.

Parameters:

fullyQualifiedClassName - The FQCN to check

Returns:

Is class available or not.

newInstance

public static <T> T newInstance(String fqcn)

Creates an instance of the class where it is searched by the algorithm described at the forName(String) method using the no-arg constructor.

Type Parameters:

T - Convenient generic so cast is not needed.

Parameters:

fqcn - The FQCN to instantiate.

Returns:

The instantiated class.

Throws:

UnknownClassException - if the class cannot be found.

InstantiationException - if the class instantiation went wrong.

newInstance

public static <T> T newInstance(String fqcn,
                                Object... args)

Creates an instance of the class where it is searched by the algorithm described at the forName(String) method with a constructor matching the arguments.

Type Parameters:

T - Convenient generic so cast is not needed.

Parameters:

fqcn - The FQCN to instantiate.

args - The arguments for the constructor

Returns:

The instantiated class.

Throws:

UnknownClassException - if the class cannot be found.

InstantiationException - if the class instantiation went wrong.

newInstance

public static <T> T newInstance(Class clazz)

Creates an instance of the class using the no-arg constructor.

Type Parameters:

T - Convenient generic so cast is not needed.

Parameters:

clazz - Class which needs to instantiated.

Returns:

The instantiated class.

Throws:

InstantiationException - if the class instantiation went wrong.

newInstance

public static <T> T newInstance(Class clazz,
                                Object... args)

Creates an instance of the class with a constructor matching the arguments.

Type Parameters:

T - Convenient generic so cast is not needed.

Parameters:

clazz - Class which needs to instantiated.

args - The arguments for the constructor

Returns:

The instantiated class.

Throws:

InstantiationException - if the class instantiation went wrong.