org.iternine.jeppetto.enhance

Class ClassLoadingUtil

java.lang.Object

org.iternine.jeppetto.enhance.ClassLoadingUtil

public final class ClassLoadingUtil
extends java.lang.Object

Provides utility methods for defining javassist CtClass objects in arbitrary ClassLoaders.

This class is needed to define classes that sub-class those loaded in the system classloader. For example, given a class Foo, and the code:

 CtClass myFooExtension = ...; // use javassist to 'extend' Foo and inject bytecode
 Class cls = myFooExtension.toClass();
 Foo foo = (Foo) cls.newInstance();
 

The last line of this sample code would throw a ClassCastException because Foo, on the left, was loaded by the system classloader and MyFooExtension, on the right, was loaded in another classloader.

To work around this, use this utility:

 CtClass myFooExtension = ...; // same as above
 Class cls = ClassLoadingUtil.toClass(myFooExtension, Foo.class.getClassLoader(), null);
 Foo foo = (Foo) cls.newInstance();
 

And enjoy!

Method Summary

Modifier and Type	Method and Description
static <T> java.lang.Class<T>	toClass(javassist.CtClass ctClass) Installs the given CtClass into the current class-loader and returns it as a new class.
static <T> java.lang.Class<T>	toClass(javassist.CtClass ctClass, java.lang.ClassLoader loader, java.security.ProtectionDomain domain) Installs the given CtClass into the given class-loader and returns it as a new class.

Methods inherited from class java.lang.Object

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

Method Detail

toClass

public static <T> java.lang.Class<T> toClass(javassist.CtClass ctClass)
                                      throws javassist.CannotCompileException

Installs the given CtClass into the current class-loader and returns it as a new class.

Type Parameters:

T - class type

Parameters:

ctClass - class to load

Returns:

new class

Throws:

javassist.CannotCompileException - if the class cannot be compiled

toClass

public static <T> java.lang.Class<T> toClass(javassist.CtClass ctClass,
                                             java.lang.ClassLoader loader,
                                             java.security.ProtectionDomain domain)
                                      throws javassist.CannotCompileException

Installs the given CtClass into the given class-loader and returns it as a new class.

Type Parameters:

T - class type

Parameters:

ctClass - class to load

loader - class-loader to install into

domain - protection domain, may be null

Returns:

new class

Throws:

javassist.CannotCompileException - if the class cannot be compiled