weka.core

Class SerializationHelper

java.lang.Object

weka.core.SerializationHelper

All Implemented Interfaces:

RevisionHandler

public class SerializationHelper
extends java.lang.Object
implements RevisionHandler

A helper class for determining serialVersionUIDs and checking whether classes contain one and/or need one. One can also serialize and deserialize objects to and from files or streams.

Version:

$Revision: 14293 $

Author:

fracpete (fracpete at waikato dot ac dot nz)

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	SERIAL_VERSION_UID the field name of serialVersionUID.

Constructor Summary

Constructors

Constructor and Description
SerializationHelper()

Method Summary

Modifier and Type	Method and Description
static java.lang.ClassLoader	checkForThirdPartyClass(java.lang.String className, WekaPackageLibIsolatingClassLoader l) Checks to see if the supplied package class loader (or any of its dependent package class loaders) has the given third party class.
static java.io.ObjectInputStream	getObjectInputStream(java.io.InputStream stream) Get a (Weka package classloader aware) ObjectInputStream instance for reading objects from the supplied input stream
java.lang.String	getRevision() Returns the revision string.
static long	getUID(java.lang.Class<?> c) reads or creates the serialVersionUID for the given class.
static long	getUID(java.lang.String classname) reads or creates the serialVersionUID for the given class.
static boolean	hasUID(java.lang.Class<?> c) checks whether the given class contains a serialVersionUID.
static boolean	hasUID(java.lang.String classname) checks whether the given class contains a serialVersionUID.
static boolean	isSerializable(java.lang.Class<?> c) checks whether a class is serializable.
static boolean	isSerializable(java.lang.String classname) checks whether a class is serializable.
static void	main(java.lang.String[] args) Outputs information about a class on the commandline, takes class name as arguments.
static boolean	needsUID(java.lang.Class<?> c) checks whether a class needs to declare a serialVersionUID, i.e., it implements the java.io.Serializable interface but doesn't declare a serialVersionUID.
static boolean	needsUID(java.lang.String classname) checks whether a class needs to declare a serialVersionUID, i.e., it implements the java.io.Serializable interface but doesn't declare a serialVersionUID.
static java.lang.Object	read(java.io.InputStream stream) deserializes from the given stream and returns the object from it.
static java.lang.Object	read(java.lang.String filename) deserializes the given file and returns the object from it.
static java.lang.Object[]	readAll(java.io.InputStream stream) deserializes from the given stream and returns the object from it.
static java.lang.Object[]	readAll(java.lang.String filename) deserializes the given file and returns the objects from it.
static void	write(java.io.OutputStream stream, java.lang.Object o) serializes the given object to the specified stream.
static void	write(java.lang.String filename, java.lang.Object o) serializes the given object to the specified file.
static void	writeAll(java.io.OutputStream stream, java.lang.Object[] o) serializes the given objects to the specified stream.
static void	writeAll(java.lang.String filename, java.lang.Object[] o) serializes the given objects to the specified file.

Methods inherited from class java.lang.Object

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

Field Detail

SERIAL_VERSION_UID

public static final java.lang.String SERIAL_VERSION_UID

the field name of serialVersionUID.

See Also:

Constant Field Values

Constructor Detail

SerializationHelper

public SerializationHelper()

Method Detail

isSerializable

public static boolean isSerializable(java.lang.String classname)

checks whether a class is serializable.

Parameters:

classname - the class to check

Returns:

true if the class or one of its ancestors implements the Serializable interface, otherwise false (also if the class cannot be loaded)

isSerializable

public static boolean isSerializable(java.lang.Class<?> c)

checks whether a class is serializable.

Parameters:

c - the class to check

Returns:

true if the class or one of its ancestors implements the Serializable interface, otherwise false

hasUID

public static boolean hasUID(java.lang.String classname)

checks whether the given class contains a serialVersionUID.

Parameters:

classname - the class to check

Returns:

true if the class contains a serialVersionUID, otherwise false (also if the class is not implementing serializable or cannot be loaded)

hasUID

public static boolean hasUID(java.lang.Class<?> c)

checks whether the given class contains a serialVersionUID.

Parameters:

c - the class to check

Returns:

true if the class contains a serialVersionUID, otherwise false (also if the class is not implementing serializable)

needsUID

public static boolean needsUID(java.lang.String classname)

checks whether a class needs to declare a serialVersionUID, i.e., it implements the java.io.Serializable interface but doesn't declare a serialVersionUID.

Parameters:

classname - the class to check

Returns:

true if the class needs to declare one, false otherwise (also if the class cannot be loaded!)

needsUID

public static boolean needsUID(java.lang.Class<?> c)

checks whether a class needs to declare a serialVersionUID, i.e., it implements the java.io.Serializable interface but doesn't declare a serialVersionUID.

Parameters:

c - the class to check

Returns:

true if the class needs to declare one, false otherwise

getUID

public static long getUID(java.lang.String classname)

reads or creates the serialVersionUID for the given class.

Parameters:

classname - the class to get the serialVersionUID for

Returns:

the UID, 0L for non-serializable classes (or if the class cannot be loaded)

getUID

public static long getUID(java.lang.Class<?> c)

reads or creates the serialVersionUID for the given class.

Parameters:

c - the class to get the serialVersionUID for

Returns:

the UID, 0L for non-serializable classes

write

public static void write(java.lang.String filename,
                         java.lang.Object o)
                  throws java.lang.Exception

serializes the given object to the specified file.

Parameters:

filename - the file to write the object to

o - the object to serialize

Throws:

java.lang.Exception - if serialization fails

write

public static void write(java.io.OutputStream stream,
                         java.lang.Object o)
                  throws java.lang.Exception

serializes the given object to the specified stream.

Parameters:

stream - the stream to write the object to

o - the object to serialize

Throws:

java.lang.Exception - if serialization fails

writeAll

public static void writeAll(java.lang.String filename,
                            java.lang.Object[] o)
                     throws java.lang.Exception

serializes the given objects to the specified file.

Parameters:

filename - the file to write the object to

o - the objects to serialize

Throws:

java.lang.Exception - if serialization fails

writeAll

public static void writeAll(java.io.OutputStream stream,
                            java.lang.Object[] o)
                     throws java.lang.Exception

serializes the given objects to the specified stream.

Parameters:

stream - the stream to write the object to

o - the objects to serialize

Throws:

java.lang.Exception - if serialization fails

read

public static java.lang.Object read(java.lang.String filename)
                             throws java.lang.Exception

deserializes the given file and returns the object from it.

Parameters:

filename - the file to deserialize from

Returns:

the deserialized object

Throws:

java.lang.Exception - if deserialization fails

read

public static java.lang.Object read(java.io.InputStream stream)
                             throws java.lang.Exception

deserializes from the given stream and returns the object from it.

Parameters:

stream - the stream to deserialize from

Returns:

the deserialized object

Throws:

java.lang.Exception - if deserialization fails

checkForThirdPartyClass

public static java.lang.ClassLoader checkForThirdPartyClass(java.lang.String className,
                                                            WekaPackageLibIsolatingClassLoader l)

Checks to see if the supplied package class loader (or any of its dependent package class loaders) has the given third party class.

Parameters:

className - the name of the third-party class to check for

l - the third party class loader

Returns:

the class loader that owns the named third-party class, or null if not found.

getObjectInputStream

public static java.io.ObjectInputStream getObjectInputStream(java.io.InputStream stream)
                                                      throws java.io.IOException

Get a (Weka package classloader aware) ObjectInputStream instance for reading objects from the supplied input stream

Parameters:

stream - the stream to wrap

Returns:

an ObjectInputStream instance that is aware of of Weka package classloaders

Throws:

java.io.IOException - if a problem occurs

readAll

public static java.lang.Object[] readAll(java.lang.String filename)
                                  throws java.lang.Exception

deserializes the given file and returns the objects from it.

Parameters:

filename - the file to deserialize from

Returns:

the deserialized objects

Throws:

java.lang.Exception - if deserialization fails

readAll

public static java.lang.Object[] readAll(java.io.InputStream stream)
                                  throws java.lang.Exception

deserializes from the given stream and returns the object from it.

Parameters:

stream - the stream to deserialize from

Returns:

the deserialized object

Throws:

java.lang.Exception - if deserialization fails

getRevision

public java.lang.String getRevision()

Returns the revision string.

Specified by:

getRevision in interface RevisionHandler

Returns:

the revision

main

public static void main(java.lang.String[] args)
                 throws java.lang.Exception

Outputs information about a class on the commandline, takes class name as arguments.

Parameters:

args - the classnames to check

Throws:

java.lang.Exception - if something goes wrong