Module org.eclipse.persistence.core

Package org.eclipse.persistence.dynamic

Class DynamicClassWriter

java.lang.Object

org.eclipse.persistence.dynamic.DynamicClassWriter

All Implemented Interfaces:

EclipseLinkClassWriter

Direct Known Subclasses:

MetadataDynamicClassWriter, XRClassWriter

public class DynamicClassWriter
extends Object
implements EclipseLinkClassWriter

Write the byte codes of a dynamic entity class. The class writer will create the byte codes for a dynamic class that subclasses any provided class replicating its constructors and writeReplace method (if one exists).

The intent is to provide a common writer for dynamic JPA entities but also allow for subclasses of this to be used in more complex writing situations such as SDO and DBWS.

Instances of this class and any subclasses are maintained within the DynamicClassLoader.getClassWriters() and DynamicClassLoader.defaultWriter for the life of the class loader so it is important that no unnecessary state be maintained that may effect memory usage.

Since:

EclipseLink 1.2

Field Summary

Fields

Modifier and Type	Field	Description
protected static final String	CLINIT
protected static final String	DYNAMIC_PROPERTIES_MANAGER_CLASSNAME_SLASHES
static int[]	ICONST
protected static final String	INIT
protected Class<?>	parentClass
protected String	parentClassName	Name of parent class.

Constructor Summary

Constructors

Constructor	Description
DynamicClassWriter()
DynamicClassWriter(Class<?> parentClass)
DynamicClassWriter(String parentClassName)	Create using a loader and class name so that the parent class can be lazily loaded when the writer is used to generate a dynamic class.

Method Summary

Modifier and Type	Method	Description
protected void	addFields(ClassWriter cw, String parentClassType)	Allow subclasses to add additional state to the dynamic entity.
protected void	addInterface(String intf)	Allow subclasses to add additional interfaces to the dynamic entity.
protected void	addMethods(ClassWriter cw, String parentClassType)	Allow subclasses to add additional methods to the dynamic entity.
protected DynamicClassWriter	createCopy(Class<?> parentClass)	Create a copy of this DynamicClassWriter but with a different parent class.
protected byte[]	createEnum(DynamicClassLoader.EnumInfo enumInfo)
protected String[]	getInterfaces()	Interfaces the dynamic entity class implements.
Class<?>	getParentClass()
String	getParentClassName()
boolean	isCompatible(EclipseLinkClassWriter writer)	Verify that the provided writer is compatible with the current writer.
String	toString()
protected boolean	verify(Class<?> dynamicClass, ClassLoader loader)	Verify that the provided class meets the requirements of the writer.
byte[]	writeClass(DynamicClassLoader loader, String className)

Methods inherited from class java.lang.Object

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

Field Details

DYNAMIC_PROPERTIES_MANAGER_CLASSNAME_SLASHES

protected static final String DYNAMIC_PROPERTIES_MANAGER_CLASSNAME_SLASHES

INIT

protected static final String INIT

See Also:

• Constant Field Values

CLINIT

protected static final String CLINIT

See Also:

• Constant Field Values

parentClass

protected Class<?> parentClass

parentClassName

protected String parentClassName

Name of parent class. This is used only when the parent class is not known at the time the dynamic class writer is registered. This is generally only required when loading from an XML mapping file where the order of class access is not known.

ICONST

public static int[] ICONST

Constructor Details

DynamicClassWriter

public DynamicClassWriter()

DynamicClassWriter

public DynamicClassWriter(Class<?> parentClass)

DynamicClassWriter

public DynamicClassWriter(String parentClassName)

Create using a loader and class name so that the parent class can be lazily loaded when the writer is used to generate a dynamic class.

The loader must not be null and the parentClassName must not be null and not an empty String. The parentClassName will be converted to a class using the provided loader lazily.

See Also:

• getParentClass()
• DynamicException.illegalDynamicClassWriter(DynamicClassLoader, String)

Method Details

getParentClass

public Class<?> getParentClass()

Specified by:

getParentClass in interface EclipseLinkClassWriter

getParentClassName

public String getParentClassName()

Specified by:

getParentClassName in interface EclipseLinkClassWriter

writeClass

public byte[] writeClass(DynamicClassLoader loader,
 String className)
                  throws ClassNotFoundException

Specified by:

writeClass in interface EclipseLinkClassWriter

Throws:

ClassNotFoundException

addInterface

protected void addInterface(String intf)

Allow subclasses to add additional interfaces to the dynamic entity.

Parameters:

intf - additional interface

addFields

protected void addFields(ClassWriter cw,
 String parentClassType)

Allow subclasses to add additional state to the dynamic entity.

addMethods

protected void addMethods(ClassWriter cw,
 String parentClassType)

Allow subclasses to add additional methods to the dynamic entity.

createEnum

protected byte[] createEnum(DynamicClassLoader.EnumInfo enumInfo)

verify

protected boolean verify(Class<?> dynamicClass,
 ClassLoader loader)
                  throws ClassNotFoundException

Verify that the provided class meets the requirements of the writer. In the case of DynamicClassWriter this will ensure that the class is a subclass of the parentClass

Throws:

ClassNotFoundException

getInterfaces

protected String[] getInterfaces()

Interfaces the dynamic entity class implements. By default this is none but in the case of SDO a concrete interface must be implemented. Subclasses should override this as required.

Returns:

Interfaces implemented by Dynamic class. May be null

createCopy

protected DynamicClassWriter createCopy(Class<?> parentClass)

Create a copy of this DynamicClassWriter but with a different parent class.

See Also:

• DynamicClassLoader.addClass(String, Class)

isCompatible

public boolean isCompatible(EclipseLinkClassWriter writer)

Verify that the provided writer is compatible with the current writer. Returning true means that the bytes that would be created using this writer are identical with what would come from the provided writer.

Used in DynamicClassLoader.addClass(String, EclipseLinkClassWriter) to verify if a duplicate request of the same className can proceed and return the same class that may already exist.

Specified by:

isCompatible in interface EclipseLinkClassWriter

toString

public String toString()

Overrides:

toString in class Object