Package javassist.tools.reflect

Class ClassMetaobject

java.lang.Object

javassist.tools.reflect.ClassMetaobject

All Implemented Interfaces:

java.io.Serializable

public class ClassMetaobject
extends java.lang.Object
implements java.io.Serializable

A runtime class metaobject.

A ClassMetaobject is created for every class of reflective objects. It can be used to hold values shared among the reflective objects of the same class.

To obtain a class metaobject, calls _getClass() on a reflective object. For example,

ClassMetaobject cm = ((Metalevel)reflectiveObject)._getClass();
 

See Also:

Metaobject, Metalevel, Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
private java.lang.reflect.Constructor<?>[]	constructors
private java.lang.Class<?>	javaClass
(package private) static java.lang.String	methodPrefix	The base-level methods controlled by a metaobject are renamed so that they begin with methodPrefix "_m_".
(package private) static int	methodPrefixLen
private java.lang.reflect.Method[]	methods
private static long	serialVersionUID	default serialVersionUID
static boolean	useContextClassLoader	Specifies how a java.lang.Class object is loaded.

Constructor Summary

Constructors

Constructor	Description
ClassMetaobject(java.lang.String[] params)	Constructs a ClassMetaobject.

Method Summary

Modifier and Type	Method	Description
private java.lang.Class<?>	getClassObject(java.lang.String name)
java.lang.Class<?>	getJavaClass()	Obtains the java.lang.Class representing this class.
java.lang.reflect.Method	getMethod(int identifier)	Returns the java.lang.reflect.Method object representing the method specified by identifier.
int	getMethodIndex(java.lang.String originalName, java.lang.Class<?>[] argTypes)	Returns the identifier index of the method, as identified by its original name.
java.lang.String	getMethodName(int identifier)	Returns the name of the method specified by identifier.
java.lang.String	getName()	Obtains the name of this class.
java.lang.Class<?>[]	getParameterTypes(int identifier)	Returns an array of Class objects representing the formal parameter types of the method specified by identifier.
java.lang.reflect.Method[]	getReflectiveMethods()	Returns an array of the methods defined on the given reflective object.
java.lang.Class<?>	getReturnType(int identifier)	Returns a Class objects representing the return type of the method specified by identifier.
static java.lang.Object	invoke(java.lang.Object target, int identifier, java.lang.Object[] args)	Invokes a method whose name begins with methodPrefix "_m_" and the identifier.
boolean	isInstance(java.lang.Object obj)	Returns true if obj is an instance of this class.
java.lang.Object	newInstance(java.lang.Object[] args)	Creates a new instance of the class.
private void	readObject(java.io.ObjectInputStream in)
java.lang.Object	trapFieldRead(java.lang.String name)	Is invoked when static fields of the base-level class are read and the runtime system intercepts it.
void	trapFieldWrite(java.lang.String name, java.lang.Object value)	Is invoked when static fields of the base-level class are modified and the runtime system intercepts it.
java.lang.Object	trapMethodcall(int identifier, java.lang.Object[] args)	Is invoked when static methods of the base-level class are called and the runtime system intercepts it.
private void	writeObject(java.io.ObjectOutputStream out)

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

private static final long serialVersionUID

default serialVersionUID

See Also:

Constant Field Values

methodPrefix

static final java.lang.String methodPrefix

The base-level methods controlled by a metaobject are renamed so that they begin with methodPrefix "_m_".

See Also:

Constant Field Values

methodPrefixLen

static final int methodPrefixLen

See Also:

Constant Field Values

javaClass

private java.lang.Class<?> javaClass

constructors

private java.lang.reflect.Constructor<?>[] constructors

methods

private java.lang.reflect.Method[] methods

useContextClassLoader

public static boolean useContextClassLoader

Specifies how a java.lang.Class object is loaded.

If true, it is loaded by:

Thread.currentThread().getContextClassLoader().loadClass()

If false, it is loaded by Class.forName(). The default value is false.

Constructor Detail

ClassMetaobject

public ClassMetaobject(java.lang.String[] params)

Constructs a ClassMetaobject.

Parameters:

params - params[0] is the name of the class of the reflective objects.

Method Detail

writeObject

private void writeObject(java.io.ObjectOutputStream out)
                  throws java.io.IOException

Throws:

java.io.IOException

readObject

private void readObject(java.io.ObjectInputStream in)
                 throws java.io.IOException,
                        java.lang.ClassNotFoundException

Throws:

java.io.IOException

java.lang.ClassNotFoundException

getClassObject

private java.lang.Class<?> getClassObject(java.lang.String name)
                                   throws java.lang.ClassNotFoundException

Throws:

java.lang.ClassNotFoundException

getJavaClass

public final java.lang.Class<?> getJavaClass()

Obtains the java.lang.Class representing this class.

getName

public final java.lang.String getName()

Obtains the name of this class.

isInstance

public final boolean isInstance(java.lang.Object obj)

Returns true if obj is an instance of this class.

newInstance

public final java.lang.Object newInstance(java.lang.Object[] args)
                                   throws CannotCreateException

Creates a new instance of the class.

Parameters:

args - the arguments passed to the constructor.

Throws:

CannotCreateException

trapFieldRead

public java.lang.Object trapFieldRead(java.lang.String name)

Is invoked when static fields of the base-level class are read and the runtime system intercepts it. This method simply returns the value of the field.

Every subclass of this class should redefine this method.

trapFieldWrite

public void trapFieldWrite(java.lang.String name,
                           java.lang.Object value)

Is invoked when static fields of the base-level class are modified and the runtime system intercepts it. This method simply sets the field to the given value.

Every subclass of this class should redefine this method.

invoke

public static java.lang.Object invoke(java.lang.Object target,
                                      int identifier,
                                      java.lang.Object[] args)
                               throws java.lang.Throwable

Invokes a method whose name begins with methodPrefix "_m_" and the identifier.

Throws:

CannotInvokeException - if the invocation fails.

java.lang.Throwable

trapMethodcall

public java.lang.Object trapMethodcall(int identifier,
                                       java.lang.Object[] args)
                                throws java.lang.Throwable

Is invoked when static methods of the base-level class are called and the runtime system intercepts it. This method simply executes the intercepted method invocation with the original parameters and returns the resulting value.

Every subclass of this class should redefine this method.

Throws:

java.lang.Throwable

getReflectiveMethods

public final java.lang.reflect.Method[] getReflectiveMethods()

Returns an array of the methods defined on the given reflective object. This method is for the internal use only.

getMethod

public final java.lang.reflect.Method getMethod(int identifier)

Returns the java.lang.reflect.Method object representing the method specified by identifier.

Note that the actual method returned will be have an altered, reflective name i.e. _m_2_...

Parameters:

identifier - the identifier index given to trapMethodcall() etc.

See Also:

Metaobject.trapMethodcall(int,Object[]), trapMethodcall(int,Object[])

getMethodName

public final java.lang.String getMethodName(int identifier)

Returns the name of the method specified by identifier.

getParameterTypes

public final java.lang.Class<?>[] getParameterTypes(int identifier)

Returns an array of Class objects representing the formal parameter types of the method specified by identifier.

getReturnType

public final java.lang.Class<?> getReturnType(int identifier)

Returns a Class objects representing the return type of the method specified by identifier.

getMethodIndex

public final int getMethodIndex(java.lang.String originalName,
                                java.lang.Class<?>[] argTypes)
                         throws java.lang.NoSuchMethodException

Returns the identifier index of the method, as identified by its original name.

This method is useful, in conjuction with getMethod(int), to obtain a quick reference to the original method in the reflected class (i.e. not the proxy method), using the original name of the method.

Written by Brett Randall and Shigeru Chiba.

Parameters:

originalName - The original name of the reflected method

argTypes - array of Class specifying the method signature

Returns:

the identifier index of the original method

Throws:

java.lang.NoSuchMethodException - if the method does not exist

See Also:

getMethod(int)