net.bytebuddy.implementation

Class FixedValue

java.lang.Object

net.bytebuddy.implementation.FixedValue

All Implemented Interfaces:

InstrumentedType.Prepareable, Implementation

Direct Known Subclasses:

FixedValue.ForOriginType, FixedValue.ForPoolValue, FixedValue.ForStaticField

public abstract class FixedValue
extends Object
implements Implementation

This implementation returns a fixed value for a method. Other than the StubMethod implementation, this implementation allows to determine a specific value which must be assignable to the returning value of any instrumented method. Otherwise, an exception will be thrown.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	FixedValue.AssignerConfigurable Represents a fixed value implementation that is using a default assigner for attempting to assign the fixed value to the return type of the instrumented method.
protected static class	FixedValue.ForNullValue A fixed value of null.
protected static class	FixedValue.ForOriginType A fixed value that appends the origin type of the instrumented type.
protected static class	FixedValue.ForPoolValue A fixed value implementation that represents its fixed value as a value that is written to the instrumented class's constant pool.
protected static class	FixedValue.ForStaticField A fixed value implementation that represents its fixed value as a static field of the instrumented class.

Nested classes/interfaces inherited from interface net.bytebuddy.implementation.Implementation

Implementation.Composable, Implementation.Compound, Implementation.Context, Implementation.Simple, Implementation.SpecialMethodInvocation, Implementation.Target

Field Summary

Fields

Modifier and Type	Field and Description
protected Assigner	assigner The assigner that is used for assigning the fixed value to a method's return type.
protected Assigner.Typing	typing Indicates if dynamic type castings should be attempted for incompatible assignments.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	FixedValue(Assigner assigner, Assigner.Typing typing) Creates a new fixed value implementation.

Method Summary

Modifier and Type	Method and Description
protected ByteCodeAppender.Size	apply(MethodVisitor methodVisitor, Implementation.Context implementationContext, MethodDescription instrumentedMethod, TypeDescription.Generic fixedValueType, StackManipulation valueLoadingInstruction) Blueprint method that for applying the actual implementation.
boolean	equals(Object other)
int	hashCode()
static Implementation	nullValue() Returns a null value from an instrumented method.
static FixedValue.AssignerConfigurable	originType() Returns the origin type from an instrumented method.
static FixedValue.AssignerConfigurable	reference(Object fixedValue) Other than value(Object), this function will create a fixed value implementation that will always defined a field in the instrumented class.
static FixedValue.AssignerConfigurable	reference(Object fixedValue, String fieldName) Other than value(Object), this function will create a fixed value implementation that will always defined a field in the instrumented class.
static FixedValue.AssignerConfigurable	value(JavaInstance fixedValue) Returns the loaded version of the given JavaInstance.
static FixedValue.AssignerConfigurable	value(Object fixedValue) Returns a fixed value from any intercepted method.
static FixedValue.AssignerConfigurable	value(TypeDescription fixedValue) Returns the given type in form of a loaded type.

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.bytebuddy.implementation.Implementation

appender

Methods inherited from interface net.bytebuddy.dynamic.scaffold.InstrumentedType.Prepareable

prepare

Field Detail

assigner

protected final Assigner assigner

The assigner that is used for assigning the fixed value to a method's return type.

typing

protected final Assigner.Typing typing

Indicates if dynamic type castings should be attempted for incompatible assignments.

Constructor Detail

FixedValue

protected FixedValue(Assigner assigner,
                     Assigner.Typing typing)

Creates a new fixed value implementation.

Parameters:

assigner - The assigner to use for assigning the fixed value to the return type of the instrumented value.

typing - Indicates if dynamic type castings should be attempted for incompatible assignments.

Method Detail

value

public static FixedValue.AssignerConfigurable value(Object fixedValue)

Returns a fixed value from any intercepted method. The fixed value is stored in the constant pool if this is possible. Java is capable of storing any primitive value, String values and Class references in the constant pool. Since Java 7, MethodHandle as well as MethodType references are also supported. Alternatively, the fixed value is stored in a static field.

When a value is stored in the class's constant pool, its identity is lost. If an object's identity is important, the reference(Object) method should be used instead.

Important: When supplying a method handle or a method type, all types that are implied must be visible to the instrumented type or an IllegalAccessException will be thrown at runtime.

Parameters:

fixedValue - The fixed value to return from the method.

Returns:

An implementation for the given fixedValue.

reference

public static FixedValue.AssignerConfigurable reference(Object fixedValue)

Other than value(Object), this function will create a fixed value implementation that will always defined a field in the instrumented class. As a result, object identity will be preserved between the given fixedValue and the value that is returned by instrumented methods. The field name can be explicitly determined. The field name is generated from the fixed value's hash code.

Parameters:

fixedValue - The fixed value to be returned by methods that are instrumented by this implementation.

Returns:

An implementation for the given fixedValue.

reference

public static FixedValue.AssignerConfigurable reference(Object fixedValue,
                                                        String fieldName)

Other than value(Object), this function will create a fixed value implementation that will always defined a field in the instrumented class. As a result, object identity will be preserved between the given fixedValue and the value that is returned by instrumented methods. The field name can be explicitly determined.

Parameters:

fixedValue - The fixed value to be returned by methods that are instrumented by this implementation.

fieldName - The name of the field for storing the fixed value.

Returns:

An implementation for the given fixedValue.

value

public static FixedValue.AssignerConfigurable value(TypeDescription fixedValue)

Returns the given type in form of a loaded type. The value is loaded from the written class's constant pool.

Parameters:

fixedValue - The type to return from the method.

Returns:

An implementation for the given fixedValue.

value

public static FixedValue.AssignerConfigurable value(JavaInstance fixedValue)

Returns the loaded version of the given JavaInstance. The value is loaded from the written class's constant pool.

Parameters:

fixedValue - The type to return from the method.

Returns:

An implementation for the given fixedValue.

nullValue

public static Implementation nullValue()

Returns a null value from an instrumented method.

Returns:

An implementation that returns null from a method.

originType

public static FixedValue.AssignerConfigurable originType()

Returns the origin type from an instrumented method.

Returns:

An implementation that returns the origin type of the current instrumented type.

apply

protected ByteCodeAppender.Size apply(MethodVisitor methodVisitor,
                                      Implementation.Context implementationContext,
                                      MethodDescription instrumentedMethod,
                                      TypeDescription.Generic fixedValueType,
                                      StackManipulation valueLoadingInstruction)

Blueprint method that for applying the actual implementation.

Parameters:

methodVisitor - The method visitor to which the implementation is applied to.

implementationContext - The implementation context for the given implementation.

instrumentedMethod - The instrumented method that is target of the implementation.

fixedValueType - A description of the type of the fixed value that is loaded by the valueLoadingInstruction.

valueLoadingInstruction - A stack manipulation that represents the loading of the fixed value onto the operand stack.

Returns:

A representation of the stack and variable array sized that are required for this implementation.

equals

public boolean equals(Object other)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object