Package javassist.tools

Class Callback

java.lang.Object

javassist.tools.Callback

public abstract class Callback
extends Object

Creates bytecode that when executed calls back to the instance's result method.

Example of how to create and insert a callback:

 ctMethod.insertAfter(new Callback("Thread.currentThread()") {
     public void result(Object[] objects) {
         Thread thread = (Thread) objects[0];
         // do something with thread...
     }
 }.sourceCode());
 

Contains utility methods for inserts callbacks in CtBehaviour, example:

 insertAfter(ctBehaviour, new Callback("Thread.currentThread(), dummyString") {
     public void result(Object[] objects) {
         Thread thread = (Thread) objects[0];
         // do something with thread...
     }
 });
 

Author:

Marten Hedborg, Shigeru Chiba

Field Summary

Fields

Modifier and Type	Field	Description
static Map<String,Callback>	callbacks

Constructor Summary

Constructors

Constructor	Description
Callback(String src)	Constructs a new Callback object.

Method Summary

Modifier and Type	Method	Description
static void	insertAfter(CtBehavior behavior, Callback callback)	Utility method to inserts callback at the end of the body.
static void	insertAfter(CtBehavior behavior, Callback callback, boolean asFinally)	Utility method to inserts callback at the end of the body.
static int	insertAt(CtBehavior behavior, Callback callback, int lineNum)	Utility method to inserts callback at the specified line in the body.
static void	insertBefore(CtBehavior behavior, Callback callback)	Utility method to insert callback at the beginning of the body.
abstract void	result(Object[] objects)	Gets called when bytecode is executed
String	sourceCode()
String	toString()

Methods inherited from class java.lang.Object

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

Field Details

callbacks

public static Map<String,Callback> callbacks

Constructor Details

Callback

public Callback(String src)

Constructs a new Callback object.

Parameters:

src - The source code representing the inserted callback bytecode. Can be one or many single statements each returning one object. If many single statements are used they must be comma separated.

Method Details

result

public abstract void result(Object[] objects)

Gets called when bytecode is executed

Parameters:

objects - Objects that the bytecode in callback returns

toString

public String toString()

Overrides:

toString in class Object

sourceCode

public String sourceCode()

insertBefore

public static void insertBefore(CtBehavior behavior,
 Callback callback)
                         throws CannotCompileException

Utility method to insert callback at the beginning of the body.

Parameters:

callback - The callback

Throws:

CannotCompileException

See Also:

• CtBehavior.insertBefore(String)

insertAfter

public static void insertAfter(CtBehavior behavior,
 Callback callback)
                        throws CannotCompileException

Utility method to inserts callback at the end of the body. The callback is inserted just before every return instruction. It is not executed when an exception is thrown.

Parameters:

behavior - The behaviour to insert callback in

callback - The callback

Throws:

CannotCompileException

See Also:

• CtBehavior.insertAfter(String, boolean)

insertAfter

public static void insertAfter(CtBehavior behavior,
 Callback callback,
 boolean asFinally)
                        throws CannotCompileException

Utility method to inserts callback at the end of the body. The callback is inserted just before every return instruction. It is not executed when an exception is thrown.

Parameters:

behavior - The behaviour to insert callback in

callback - The callback representing the inserted.

asFinally - True if the inserted is executed Not only when the control normally returns but also when an exception is thrown. If this parameter is true, the inserted code cannot access local variables.

Throws:

CannotCompileException

See Also:

• CtBehavior.insertAfter(String, boolean)

insertAt

public static int insertAt(CtBehavior behavior,
 Callback callback,
 int lineNum)
                    throws CannotCompileException

Utility method to inserts callback at the specified line in the body.

Parameters:

behavior - The behaviour to insert callback in

callback - The callback representing.

lineNum - The line number. The callback is inserted at the beginning of the code at the line specified by this line number.

Returns:

The line number at which the callback has been inserted.

Throws:

CannotCompileException

See Also:

• CtBehavior.insertAt(int, String)