org.jbeans
Class ReflectionTools

java.lang.Object
  |
  +--org.jbeans.ReflectionTools

public class ReflectionTools

extends Object

This class is a toolkit to help in reflection. All JavaBean related methods and toolkit methods can be found in the com.bp.beans package

Author:

Brian Pontarelli

Constructor Summary

ReflectionTools()

Method Summary

static Class	convertToWrapper(Class type) Converts the type given to the correct wrapper class for that type.
static Class	findClass(String className, String packageName) Convience method that returns class given the package name and className
static Method	getMethod(Class klass, String method, Class[] params) Returns the given class' method with the name method and the parameters params.
static Method	getMethod(Object object, String method, Class[] params) Returns the given objects method with the name method and the parameters params.
static Method[]	getMethods(Object object) Gets all the methods for an object and handles all the nasty exceptions that Java reflection can throw.
static Object	instantiate(Class objectClass) Yep, another convience method that instantiates an object from a class and this is just like all the others and wraps the exceptions into one nice exception
static Object	instantiate(String className) A convience method so that a class can be instantiated by name stored in a string without all the exceptions having to be caught.
static Object	invokeMethod(Method method, Object object, Object[] params) Another convience method because invoking a reflected method is a really pain in the butt.
static boolean	isSimpleReturnType(Method method) This method makes a really big blanket statement by stating that all simple types (wrapper classe and string) are in java.lang package.

Methods inherited from class java.lang.Object

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

Constructor Detail

ReflectionTools

public ReflectionTools()

Method Detail

findClass

public static Class findClass(String className,
                              String packageName)
                       throws ReflectionException

Convience method that returns class given the package name and className

Parameters:

className - The name of the class (ie Foo)

packageName - (Optional) The name of the package (ie com.xor.util)

Returns:

The Class object for the class if it is found

Throws:

ReflectionException - If the class name is invalid

getMethod

public static Method getMethod(Object object,
                               String method,
                               Class[] params)
                        throws ReflectionException

Returns the given objects method with the name method and the parameters params. This is really just a convience method so that code doesn't have to catch all five thousand exceptions that Java reflection throws and make nifty error messages, this does all of that for you and throws a single, simple exception instead

Parameters:

obejct - The object to get the method from

method - The name of the method to fetch

params - The params to the method (can be null if the method does not take any parameters)

Returns:

The Method

Throws:

ReflectionException - If anything went wrong in the reflection, like wrong arguments to the method or invalid method name. This exception has a very good message body that tells exactly what the hell you screwed up

getMethod

public static Method getMethod(Class klass,
                               String method,
                               Class[] params)
                        throws ReflectionException

Returns the given class' method with the name method and the parameters params. This is really just a convience method so that code doesn't have to catch all five thousand exceptions that Java reflection throws and make nifty error messages, this does all of that for you and throws a single, simple exception instead

Parameters:

klass - The class object to get the method from

method - The name of the method to fetch

params - The params to the method (can be null if the method does not take any parameters)

Returns:

The Method

Throws:

ReflectionException - If anything went wrong in the reflection, like wrong arguments to the method or invalid method name. This exception has a very good message body that tells exactly what the hell you screwed up

getMethods

public static Method[] getMethods(Object object)
                           throws ReflectionException

Gets all the methods for an object and handles all the nasty exceptions that Java reflection can throw. This throws a nice exception

Parameters:

object - The object to get the methods from (only the public ones)

Returns:

The methods

Throws:

ReflectionException - If anything bad happened during reflection

invokeMethod

public static Object invokeMethod(Method method,
                                  Object object,
                                  Object[] params)
                           throws ReflectionException,
                                  RuntimeException,
                                  Error

Another convience method because invoking a reflected method is a really pain in the butt. It can throw like five billion exceptions and really make coding a lame experience. So, I've wrapped all those exceptions up and thrown a nice exception of my own making called ReflectionException. Although, for debugging purposes, this method will re-throw invocation target exceptions of type Error and RuntimeException. For example, NullPointerExceptions and OutOfMemoryError are not wrapped in a ReflectionException. Instead they are re-thrown. All other invocation target exceptions are unwrapped from the InvocationTargetException class and re-wrapped into a new ReflectionException as the target property.

Parameters:

method - The method to invoke

object - The object to invoke the method on

params - The params to the method

Returns:

The return value from the method

Throws:

ReflectionException - If any mishap occurred whilst Reflecting sire. All the exceptions that could be thrown whilst invoking will be wrapped inside the ReflectionException

RuntimeException - If the target of the InvocationTargetException is a RuntimeException, in which case, it is re-thrown

Error - If the target of the InvocationTargetException is an Error, in which case, it is re-thrown

instantiate

public static Object instantiate(Class objectClass)
                          throws ReflectionException

Yep, another convience method that instantiates an object from a class and this is just like all the others and wraps the exceptions into one nice exception

Parameters:

objectClass - The class to instantiate

Returns:

The new instance of the class

Throws:

ReflectionException - If you did something really dumb like put a security restriction on the class or tried to call a class that doesn't have a default constructor of something lame like that.

instantiate

public static Object instantiate(String className)
                          throws ReflectionException

A convience method so that a class can be instantiated by name stored in a string without all the exceptions having to be caught. Instead a single ReflectionException is caught and contains a descriptive message about the error

Parameters:

className - The name of the class to instantiate

Returns:

The new instance of the class

Throws:

ReflectionException - if something went wrong during name lookup or instantiation

isSimpleReturnType

public static boolean isSimpleReturnType(Method method)

This method makes a really big blanket statement by stating that all simple types (wrapper classe and string) are in java.lang package. Although this is true, java.lang also includes non-simple types and therefore this function will fail if the caller passes it a method whose return type is a non-simple type from java.lang

Parameters:

method - The method to check

Returns:

True if the methods return type is either a wrapper class or String

convertToWrapper

public static Class convertToWrapper(Class type)

Converts the type given to the correct wrapper class for that type. If the type given is not a primitive type then null is returned. If the type given is a wrapper class, then null is returned.

Parameters:

type - The type of convert to its wrapper class

Returns:

The wrapper type for the type given or null