org.jpox.enhancer.asm
Class ASMClassEnhancer

java.lang.Object
  org.jpox.enhancer.AbstractClassEnhancer
      org.jpox.enhancer.asm.ASMClassEnhancer

All Implemented Interfaces:

ClassEnhancer

public class ASMClassEnhancer
extends AbstractClassEnhancer

Class enhancer using ASM (http://asm.objectweb.org). Assumes that the version of ASM is 3.0 or above. ASM operates using a SAXParser-like "visitor-pattern". We utilise this as follows :-

• enhance : start with a ClassReader for the class to be enhanced, and create a JdoClassAdapter (attached to a ClassWriter) that will perform the modifications, and use that as a visitor for the reader so that the reader sends its events to the adapter. Within the JdoClassAdapter we also make use of a JdoMethodAdapter to update individual methods
• check : take a ClassReader, and create a JdoClassChecker that performs the checks. We then set the checker as a visitor for the reader so that the reader sends its events to the checker.

Version:

$Revision: 1.23 $

Nested Class Summary

static class

ASMClassEnhancer.MyClassVisitor Convenience class to look up the class name for a file.

Field Summary

protected java.lang.String	asmClassName ASM Class name for this class (replace .
protected byte[]	classBytes Bytes of the class (after enhancing).
protected java.lang.String	classDescriptor Class descriptor for this class.
protected java.lang.Class	cls Class that is being enhanced.
protected byte[]	inputBytes Bytes of the input class (only when enhancing generated classes with no class file).
protected java.lang.String	inputResourceName Resource name of the input class (only when the class exists in a class file).

Fields inherited from class org.jpox.enhancer.AbstractClassEnhancer

className, clr, cmd, fieldsToAdd, initialised, LOCALISER, methodsToAdd, update

Fields inherited from interface org.jpox.enhancer.ClassEnhancer

CN_BitSet, CN_ByteIdentity, CN_CharIdentity, CN_Class, CN_ClassCastException, CN_Detachable, CN_IllegalArgumentException, CN_IllegalStateException, CN_IntIdentity, CN_JDODetachedFieldAccessException, CN_JDOFatalInternalException, CN_JDOHelper, CN_JDOImplHelper, CN_LongIdentity, CN_ObjectIdentity, CN_ObjectIdFieldConsumer, CN_ObjectIdFieldSupplier, CN_PersistenceCapable, CN_PersistenceManager, CN_ShortIdentity, CN_StateManager, CN_StringIdentity, FN_FieldFlags, FN_FieldNames, FN_FieldTypes, FN_Flag, FN_JdoDetachedState, FN_JdoInheritedFieldCount, FN_PersistenceCapableSuperclass, FN_serialVersionUID, FN_StateManager, MN_FieldFlagsInitMethod, MN_FieldNamesInitMethod, MN_FieldTypesInitMethod, MN_JdoCopyField, MN_JdoCopyFields, MN_JdoCopyKeyFieldsFromObjectId, MN_JdoCopyKeyFieldsToObjectId, MN_JdoGetInheritedFieldCount, MN_JdoGetManagedFieldCount, MN_JdoGetObjectId, MN_JdoGetPersistenceManager, MN_JdoGetTransactionalObjectId, MN_JdoGetVersion, MN_JdoIsDeleted, MN_JdoIsDetached, MN_JdoIsDetachedInternal, MN_JdoIsDirty, MN_JdoIsNew, MN_JdoIsPersistent, MN_JdoIsTransactional, MN_jdoLoadClass, MN_JdoMakeDirty, MN_JdoMakeDirtyDetached, MN_JdoNewInstance, MN_JdoNewObjectIdInstance, MN_JdoPersistenceCapableSuperclassInit, MN_JdoPreSerialize, MN_JdoProvideField, MN_JdoProvideFields, MN_JdoReplaceDetachedState, MN_JdoReplaceField, MN_JdoReplaceFields, MN_JdoReplaceFlags, MN_JdoReplaceStateManager, MN_JdoSuperClone

Constructor Summary

ASMClassEnhancer(org.jpox.metadata.ClassMetaData cmd, org.jpox.ClassLoaderResolver clr)
Constructor.

ASMClassEnhancer(org.jpox.metadata.ClassMetaData cmd, org.jpox.ClassLoaderResolver clr, byte[] classBytes)
Constructor.

Method Summary

protected boolean	checkClassIsEnhanced(boolean logErrors) Convenience method to return if a class is enhanced.
boolean	checkEnhanced() Check whether the class is enhanced.
boolean	enhance() Method to enhance a classes definition.
java.lang.String	getASMClassName() Accessor for the ASM class name
byte[]	getBytes() Accessor for the class bytes.
java.lang.String	getClassDescriptor() Accessor for the class descriptor for the class being enhanced
java.lang.Class	getClassEnhanced() Accessor for the class being enhanced.
static java.lang.String	getClassNameForFileName(java.lang.String filename) Convenience accessor for the class name that is stored in a particular class.
protected void	initialiseFieldsList() Method to initialise the list of fields to add.
protected void	initialiseMethodsList() Method to initialise the list of methods to add.
void	save(java.lang.String directoryName) Method to save the class definition bytecode into a class file.
void	verify() Verify mode for class files.

Methods inherited from class org.jpox.enhancer.AbstractClassEnhancer

getClassLoaderResolver, getClassMetaData, getFieldsList, getMethodsList, initialise, isPersistenceCapable, requiresDetachable

Methods inherited from class java.lang.Object

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

Field Detail

inputResourceName

protected java.lang.String inputResourceName

Resource name of the input class (only when the class exists in a class file).

inputBytes

protected byte[] inputBytes

Bytes of the input class (only when enhancing generated classes with no class file).

cls

protected final java.lang.Class cls

Class that is being enhanced.

classBytes

protected byte[] classBytes

Bytes of the class (after enhancing).

asmClassName

protected java.lang.String asmClassName

ASM Class name for this class (replace . with /).

classDescriptor

protected java.lang.String classDescriptor

Class descriptor for this class.

Constructor Detail

ASMClassEnhancer

public ASMClassEnhancer(org.jpox.metadata.ClassMetaData cmd,
                        org.jpox.ClassLoaderResolver clr)

Constructor.

Parameters:

cmd - MetaData for the class to be enhanced

clr - ClassLoader resolver

ASMClassEnhancer

public ASMClassEnhancer(org.jpox.metadata.ClassMetaData cmd,
                        org.jpox.ClassLoaderResolver clr,
                        byte[] classBytes)

Constructor.

Parameters:

cmd - MetaData for the class to be enhanced

clr - ClassLoader resolver

Method Detail

getClassNameForFileName

public static java.lang.String getClassNameForFileName(java.lang.String filename)

Convenience accessor for the class name that is stored in a particular class.

Parameters:

filename - Name of the file

Returns:

The class name

getClassEnhanced

public java.lang.Class getClassEnhanced()

Accessor for the class being enhanced.

Returns:

Class being enhanced

getASMClassName

public java.lang.String getASMClassName()

Accessor for the ASM class name

Returns:

ASM class name

getClassDescriptor

public java.lang.String getClassDescriptor()

Accessor for the class descriptor for the class being enhanced

Returns:

class descriptor

initialiseMethodsList

protected void initialiseMethodsList()

Method to initialise the list of methods to add.

Specified by:

initialiseMethodsList in class AbstractClassEnhancer

initialiseFieldsList

protected void initialiseFieldsList()

Method to initialise the list of fields to add.

Specified by:

initialiseFieldsList in class AbstractClassEnhancer

enhance

public boolean enhance()

Method to enhance a classes definition.

Returns:

Whether it was enhanced with no errors

getBytes

public byte[] getBytes()

Accessor for the class bytes. Only has relevance to be called after enhance().

Returns:

The class bytes

save

public void save(java.lang.String directoryName)
          throws java.io.IOException

Method to save the class definition bytecode into a class file. If directoryName is specified it will be written to $directoryName/className.class else will overwrite the existing class.

Specified by:

save in interface ClassEnhancer

Overrides:

save in class AbstractClassEnhancer

Parameters:

directoryName - Name of a directory (or null to overwrite the class)

Throws:

java.io.IOException - If an I/O error occurs in the write.

checkEnhanced

public boolean checkEnhanced()

Description copied from interface: ClassEnhancer

Check whether the class is enhanced.

Returns:

Return true if already enhanced class.

verify

public void verify()
            throws java.lang.Exception

Verify mode for class files. ASM ClassEnhancer doesn't support this so just throws an exception.

Specified by:

verify in interface ClassEnhancer

Overrides:

verify in class AbstractClassEnhancer

Throws:

java.lang.Exception - Thrown if an error occurs.

checkClassIsEnhanced

protected boolean checkClassIsEnhanced(boolean logErrors)

Convenience method to return if a class is enhanced.

Parameters:

logErrors - Whether to log any errors (missing methods etc) as errors (otherwise info/debug)

Returns:

Whether the class is enhanced