ptolemy.backtrack.util
Class ClassFileLoader

java.lang.Object
  java.lang.ClassLoader
      java.security.SecureClassLoader
          java.net.URLClassLoader
              ptolemy.backtrack.util.ClassFileLoader

public class ClassFileLoader
extends java.net.URLClassLoader

Class loader that tries to load a class from the given file. This class loader, unlike other class loaders that accept class names and load classes with those names, accepts class file names and loads them as classes. It uses defineClass(java.lang.String, sun.misc.Resource) in URLClassLoader to define the class with the contents in the given file. If error occurs, it falls back to traditional class loading with the class name in the exception message.

Since:

Ptolemy II 5.1

Version:

$Id: ClassFileLoader.java 57040 2010-01-27 20:52:32Z cxh $

Author:

Thomas Feng

Accepted Rating:

Red (tfeng)

Proposed Rating:

Red (tfeng)

Constructor Summary

ClassFileLoader()
Construct a class loader with no special class path.

ClassFileLoader(java.lang.String[] classPaths)
Construct a class loader with a set of class paths specified as a string array.

Method Summary

java.lang.Class

loadClass(java.io.File classFile) Load a class defined in a file, and return the Class object of the class.

Methods inherited from class java.net.URLClassLoader

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

Methods inherited from class java.security.SecureClassLoader

defineClass, defineClass

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, 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, toString, wait, wait, wait

Constructor Detail

ClassFileLoader

public ClassFileLoader()
                throws java.net.MalformedURLException

Construct a class loader with no special class path. This class loader can only load Java built-in classes indirectly, when they are required by the class file to be loaded.

Throws:

java.net.MalformedURLException - If a string is not a proper URL.

ClassFileLoader

public ClassFileLoader(java.lang.String[] classPaths)
                throws java.net.MalformedURLException

Construct a class loader with a set of class paths specified as a string array. When the class file to be loaded requires other classes, this class loader loads those required classes with the given class paths.

Parameters:

classPaths - The array of class paths to be searched in order.

Throws:

java.net.MalformedURLException - If a string is not a proper URL.

Method Detail

loadClass

public java.lang.Class loadClass(java.io.File classFile)
                          throws java.io.FileNotFoundException,
                                 java.io.IOException,
                                 java.lang.LinkageError,
                                 java.lang.ClassNotFoundException

Load a class defined in a file, and return the Class object of the class.

Parameters:

classFile - The file that defines the class.

Returns:

The object of the loaded class.

Throws:

java.io.FileNotFoundException - If the file cannot be found.

java.io.IOException - If error occurs when trying to read the file.

java.lang.LinkageError - If URLClassLoader.defineClass(java.lang.String, sun.misc.Resource) issues a LinkageError and fails to define the class.

java.lang.ClassNotFoundException - If some classes referenced by the class in the file cannot be found.