org.eclipse.persistence.dynamic
Class DynamicClassLoader

java.lang.Object
  java.lang.ClassLoader
      org.eclipse.persistence.dynamic.DynamicClassLoader

public class DynamicClassLoader
extends java.lang.ClassLoader

This custom ClassLoader provides support for dynamically generating classes within an EclipseLink application using byte codes created using a DynamicClassWriter. A DynamicClassLoader requires a parent or delegate class-loader which is provided to the constructor. This delegate class loader handles the lookup and storage of all created classes.

Author:

dclarke, mnorman

Since:

EclipseLink 1.2

Field Summary

protected java.util.Map<java.lang.String,DynamicClassWriter>	classWriters Map of DynamicClassWriter used to dynamically create a class in the findClass(String) call.
DynamicClassWriter	defaultWriter Default writer to use if one is not specified.

Constructor Summary

DynamicClassLoader(java.lang.ClassLoader delegate)
Create a DynamicClassLoader providing the delegate loader and leaving the defaultWriter as DynamicClassWriter

DynamicClassLoader(java.lang.ClassLoader delegate, DynamicClassWriter writer)
Create a DynamicClassLoader providing the delegate loader and a default DynamicClassWriter.

Method Summary

void	addClass(java.lang.String className) Register a class to be dynamically created using the default DynamicClassWriter.
void	addClass(java.lang.String className, java.lang.Class<?> parentClass) Register a class to be dynamically created using a copy of default DynamicClassWriter but specifying a different parent class.
void	addClass(java.lang.String className, DynamicClassWriter writer) Register a class to be dynamically created using the provided DynamicClassWriter.
java.lang.Class<?>	createDynamicClass(java.lang.String className) Create a new dynamic entity type for the specified name assuming the use of the default writer and its default parent class.
java.lang.Class<?>	createDynamicClass(java.lang.String className, java.lang.Class<?> parentClass) Create a new dynamic entity type for the specified name with the specified parent class.
java.lang.Class<?>	createDynamicClass(java.lang.String className, DynamicClassWriter writer) Create a dynamic class registering a writer and then forcing the provided class name to be loaded.
protected java.lang.Class<?>	findClass(java.lang.String className) Create a new dynamic class if a ClassWriter is registered for the provided className.
DynamicClassWriter	getClassWriter(java.lang.String className)
protected java.util.Map<java.lang.String,DynamicClassWriter>	getClassWriters()
DynamicClassWriter	getDefaultWriter()
static DynamicClassLoader	lookup(Session session) Lookup the DynamicConversionManager for the given session.

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findLibrary, findLoadedClass, findResource, findResources, 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

Field Detail

classWriters

protected java.util.Map<java.lang.String,DynamicClassWriter> classWriters

Map of DynamicClassWriter used to dynamically create a class in the findClass(String) call. The application must register classes using addClass or createDynameClass prior to the findClass(String) being invoked.

The map of writers is maintained for the life of this DynamicClassLoader instance to ensure additional requests to create dynamic classes of the same name are properly verified. Duplicate requests for dynamic classes of the same name, same writer type, and the same parent class are permitted but different parent classes or different writer types are not.

defaultWriter

public DynamicClassWriter defaultWriter

Default writer to use if one is not specified.

Constructor Detail

DynamicClassLoader

public DynamicClassLoader(java.lang.ClassLoader delegate)

Create a DynamicClassLoader providing the delegate loader and leaving the defaultWriter as DynamicClassWriter

DynamicClassLoader

public DynamicClassLoader(java.lang.ClassLoader delegate,
                          DynamicClassWriter writer)

Create a DynamicClassLoader providing the delegate loader and a default DynamicClassWriter.

Method Detail

getDefaultWriter

public DynamicClassWriter getDefaultWriter()

getClassWriters

protected java.util.Map<java.lang.String,DynamicClassWriter> getClassWriters()

getClassWriter

public DynamicClassWriter getClassWriter(java.lang.String className)

addClass

public void addClass(java.lang.String className)

Register a class to be dynamically created using the default DynamicClassWriter.

See Also:

addClass(String, DynamicClassWriter)

addClass

public void addClass(java.lang.String className,
                     java.lang.Class<?> parentClass)

Register a class to be dynamically created using a copy of default DynamicClassWriter but specifying a different parent class.

See Also:

addClass(String, DynamicClassWriter)

addClass

public void addClass(java.lang.String className,
                     DynamicClassWriter writer)
              throws DynamicException

Register a class to be dynamically created using the provided DynamicClassWriter. The registered writer is used when the findClass(String) method is called back on this loader from the ClassLoader.loadClass(String) call.

If a duplicate request is made for the same className and the writers are not compatible a DynamicException will be thrown. If the duplicate request contains a compatible writer then the second request is ignored as the class may already have been generated.

Throws:

DynamicException

See Also:

findClass(String)

createDynamicClass

public java.lang.Class<?> createDynamicClass(java.lang.String className,
                                             DynamicClassWriter writer)
                                      throws DynamicException

Create a dynamic class registering a writer and then forcing the provided class name to be loaded.

Throws:

DynamicException

createDynamicClass

public java.lang.Class<?> createDynamicClass(java.lang.String className)

Create a new dynamic entity type for the specified name assuming the use of the default writer and its default parent class.

See Also:

#creatDynamicClass(String, DynamicClassWriter)

createDynamicClass

public java.lang.Class<?> createDynamicClass(java.lang.String className,
                                             java.lang.Class<?> parentClass)

Create a new dynamic entity type for the specified name with the specified parent class.

See Also:

#creatDynamicClass(String, DynamicClassWriter)

findClass

protected java.lang.Class<?> findClass(java.lang.String className)
                                throws java.lang.ClassNotFoundException

Create a new dynamic class if a ClassWriter is registered for the provided className. This code is single threaded to ensure only one class is created for a given name and that the ClassWriter is removed afterwards.

Overrides:

findClass in class java.lang.ClassLoader

Throws:

java.lang.ClassNotFoundException

lookup

public static DynamicClassLoader lookup(Session session)

Lookup the DynamicConversionManager for the given session. If the existing ConversionManager is not an instance of DynamicConversionManager then create a new one and replace the existing one.

Parameters:

session -

Returns: