tauzaman
Class ClassLoaderMethodCaller

java.lang.Object
  |
  +--java.lang.ClassLoader
        |
        +--java.security.SecureClassLoader
              |
              +--java.net.URLClassLoader
                    |
                    +--tauzaman.ClassLoaderMethodCaller

public class ClassLoaderMethodCaller

extends java.net.URLClassLoader

ClassLoaderMethodCaller class dynamically loads a Class and provide service for calling any of loaded Methods.

Classes that will make use of ClassLoaderMethodCaller are;

• IrregularMapping objects for their methods. Also, IrregularMappings will be used in granularityLattice, which is still in design stage.
• Calendar because of regular methods. regular functions refer to two functions, which all Calendars should have: "granuleToFields and fieldsToGranule".
• FVFunction because of Field Value functions.

See Also:

IrregularMapping, Calendar, FVFunction

Status:

Design complete, implementation not started

Field Summary

private java.util.Hashtable

methodsToClass A Hashtable, which maps methods of this CLMC to loaded classes.

Fields inherited from class java.net.URLClassLoader

Fields inherited from class java.security.SecureClassLoader

Fields inherited from class java.lang.ClassLoader

Constructor Summary

ClassLoaderMethodCaller(java.net.URL[] urls)
Constructs a ClassLoaderMethodCaller object with specified URLs.

Method Summary

java.lang.Object	callMethod(java.lang.String methodName, java.lang.Class[] parameterTypes, java.lang.Object[] args) Calls method with specified method name with specified actual parameters.
void	loadClass(java.lang.String className, java.lang.String methodName) Finds and loads the class with the specified name from the URL search path.
java.lang.String	toString() Returns string representation of method name - class name mapping of this ClassLoaderMethodCaller.

Methods inherited from class java.net.URLClassLoader

addURL, definePackage, findClass, findResource, findResources, getPermissions, getURLs, newInstance, newInstance

Methods inherited from class java.security.SecureClassLoader

defineClass

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, definePackage, findLibrary, findLoadedClass, findSystemClass, getPackage, getPackages, getParent, getResource, getResourceAsStream, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, loadClass, resolveClass, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners

Methods inherited from class java.lang.Object

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

Field Detail

methodsToClass

private java.util.Hashtable methodsToClass

A Hashtable, which maps methods of this CLMC to loaded classes.

Constructor Detail

ClassLoaderMethodCaller

public ClassLoaderMethodCaller(java.net.URL[] urls)

Constructs a ClassLoaderMethodCaller object with specified URLs. Any URL that ends with a '/' is assumed to refer to a directory. Otherwise, the URL is assumed to refer to a JAR file which will be downloaded and opened as needed.

Although constructor takes an array of URLs, we only use first URL in this array since urls in the system are always either contain a single class or point to a directory or a .jar file, which contain multiple classes.

Parameters:

urls - array of URLs

Method Detail

loadClass

public void loadClass(java.lang.String className,
                      java.lang.String methodName)
               throws DynamicLoadException

Finds and loads the class with the specified name from the URL search path. Method name is given for mapping purposes. If the class is already loaded then keep silent and use it.

Parameters:

className - name of the class to be searched and loaded

methodName - name of the method related to loaded class

Throws:

java.lang.Exception - if any abnormal condition occurs when loading a class, Exception may further be specialized

DynamicLoadException

callMethod

public java.lang.Object callMethod(java.lang.String methodName,
                                   java.lang.Class[] parameterTypes,
                                   java.lang.Object[] args)
                            throws DynamicLoadException

Calls method with specified method name with specified actual parameters. Returns return value of the method as an Object. Instance of the class that contains this method will be formed here.

Parameters:

methodName - name of the Method to be called

parameterTypes - the list of parameters. This is passed as a parameter instead of having fix names (which can also be done) to allow generality for a possible changes in future time.

args - the arguments used for the method call

Throws:

java.lang.Exception - if any abnormal condition occurs when loading a class, Exception may further be specialized

DynamicLoadException

toString

public java.lang.String toString()

Returns string representation of method name - class name mapping of this ClassLoaderMethodCaller.

Overrides:

toString in class java.lang.Object

Returns:

String string representation of this ClassLoaderMethodCaller