javassist
Class CtBehavior

java.lang.Object
  extended by javassist.CtMember
      extended by javassist.CtBehavior
Direct Known Subclasses:
CtConstructor, CtMethod

public abstract class CtBehavior
extends CtMember

CtBehavior represents a method, a constructor, or a static constructor (class initializer). It is the abstract super class of CtMethod and CtConstructor.


Method Summary
 void addCatch(java.lang.String src, CtClass exceptionType)
          Adds a catch clause that handles an exception thrown in the body.
 void addCatch(java.lang.String src, CtClass exceptionType, java.lang.String exceptionName)
          Adds a catch clause that handles an exception thrown in the body.
 void addLocalVariable(java.lang.String name, CtClass type)
          Declares a new local variable.
 java.lang.Object[] getAnnotations()
          Returns the annotations associated with this method or constructor.
 byte[] getAttribute(java.lang.String name)
          Obtains an attribute with the given name.
 java.lang.Object[] getAvailableAnnotations()
          Returns the annotations associated with this method or constructor.
 java.lang.Object[][] getAvailableParameterAnnotations()
          Returns the parameter annotations associated with this method or constructor.
 CtClass[] getExceptionTypes()
          Obtains exceptions that this method/constructor may throw.
abstract  java.lang.String getLongName()
          Returns the method or constructor name followed by parameter types such as javassist.CtBehavior.stBody(String).
 MethodInfo getMethodInfo()
          Returns the MethodInfo representing this method/constructor in the class file.
 MethodInfo getMethodInfo2()
          Returns the MethodInfo representing the method/constructor in the class file (read only).
 int getModifiers()
          Obtains the modifiers of the method/constructor.
 java.lang.Object[][] getParameterAnnotations()
          Returns the parameter annotations associated with this method or constructor.
 CtClass[] getParameterTypes()
          Obtains parameter types of this method/constructor.
 java.lang.String getSignature()
          Returns the method signature (the parameter types and the return type).
 void insertAfter(java.lang.String src)
          Inserts bytecode at the end of the body.
 void insertAfter(java.lang.String src, boolean asFinally)
          Inserts bytecode at the end of the body.
 int insertAt(int lineNum, boolean modify, java.lang.String src)
          Inserts bytecode at the specified line in the body.
 int insertAt(int lineNum, java.lang.String src)
          Inserts bytecode at the specified line in the body.
 void insertBefore(java.lang.String src)
          Inserts bytecode at the beginning of the body.
 void instrument(CodeConverter converter)
          Modifies the method/constructor body.
 void instrument(ExprEditor editor)
          Modifies the method/constructor body.
abstract  boolean isEmpty()
          Returns true if the body is empty.
 void setAttribute(java.lang.String name, byte[] data)
          Adds an attribute.
 void setBody(java.lang.String src)
          Sets a method/constructor body.
 void setBody(java.lang.String src, java.lang.String delegateObj, java.lang.String delegateMethod)
          Sets a method/constructor body.
 void setExceptionTypes(CtClass[] types)
          Sets exceptions that this method/constructor may throw.
 void setModifiers(int mod)
          Sets the encoded modifiers of the method/constructor.
 void useCflow(java.lang.String name)
          Declares to use $cflow for this method/constructor.
 
Methods inherited from class javassist.CtMember
getDeclaringClass, getName, toString, visibleFrom
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Method Detail

getLongName

public abstract java.lang.String getLongName()
Returns the method or constructor name followed by parameter types such as javassist.CtBehavior.stBody(String).

Since:
3.5

getMethodInfo

public MethodInfo getMethodInfo()
Returns the MethodInfo representing this method/constructor in the class file.


getMethodInfo2

public MethodInfo getMethodInfo2()
Returns the MethodInfo representing the method/constructor in the class file (read only). Normal applications do not need calling this method. Use getMethodInfo().

The MethodInfo object obtained by this method is read only. Changes to this object might not be reflected on a class file generated by toBytecode(), toClass(), etc in CtClass.

This method is available even if the CtClass containing this method is frozen. However, if the class is frozen, the MethodInfo might be also pruned.

See Also:
getMethodInfo(), CtClass.isFrozen(), CtClass.prune()

getModifiers

public int getModifiers()
Obtains the modifiers of the method/constructor.

Specified by:
getModifiers in class CtMember
Returns:
modifiers encoded with javassist.Modifier.
See Also:
Modifier

setModifiers

public void setModifiers(int mod)
Sets the encoded modifiers of the method/constructor.

Changing the modifiers may cause a problem. For example, if a non-static method is changed to static, the method will be rejected by the bytecode verifier.

Specified by:
setModifiers in class CtMember
See Also:
Modifier

getAnnotations

public java.lang.Object[] getAnnotations()
                                  throws java.lang.ClassNotFoundException
Returns the annotations associated with this method or constructor.

Specified by:
getAnnotations in class CtMember
Returns:
an array of annotation-type objects.
Throws:
java.lang.ClassNotFoundException
Since:
3.1
See Also:
getAvailableAnnotations()

getAvailableAnnotations

public java.lang.Object[] getAvailableAnnotations()
Returns the annotations associated with this method or constructor. If any annotations are not on the classpath, they are not included in the returned array.

Specified by:
getAvailableAnnotations in class CtMember
Returns:
an array of annotation-type objects.
Since:
3.3
See Also:
getAnnotations()

getParameterAnnotations

public java.lang.Object[][] getParameterAnnotations()
                                             throws java.lang.ClassNotFoundException
Returns the parameter annotations associated with this method or constructor.

Returns:
an array of annotation-type objects. The length of the returned array is equal to the number of the formal parameters. If each parameter has no annotation, the elements of the returned array are empty arrays.
Throws:
java.lang.ClassNotFoundException
Since:
3.1
See Also:
getAvailableParameterAnnotations(), getAnnotations()

getAvailableParameterAnnotations

public java.lang.Object[][] getAvailableParameterAnnotations()
Returns the parameter annotations associated with this method or constructor. If any annotations are not on the classpath, they are not included in the returned array.

Returns:
an array of annotation-type objects. The length of the returned array is equal to the number of the formal parameters. If each parameter has no annotation, the elements of the returned array are empty arrays.
Since:
3.3
See Also:
getParameterAnnotations(), getAvailableAnnotations()

getParameterTypes

public CtClass[] getParameterTypes()
                            throws NotFoundException
Obtains parameter types of this method/constructor.

Throws:
NotFoundException

getSignature

public java.lang.String getSignature()
Returns the method signature (the parameter types and the return type). The method signature is represented by a character string called method descriptor, which is defined in the JVM specification. If two methods/constructors have the same parameter types and the return type, getSignature() returns the same string (the return type of constructors is void).

Note that the returned string is not the type signature contained in the SignatureAttirbute. It is a descriptor. To obtain a type signature, call the following methods:

Specified by:
getSignature in class CtMember
See Also:
Descriptor, SignatureAttribute

getExceptionTypes

public CtClass[] getExceptionTypes()
                            throws NotFoundException
Obtains exceptions that this method/constructor may throw.

Returns:
a zero-length array if there is no throws clause.
Throws:
NotFoundException

setExceptionTypes

public void setExceptionTypes(CtClass[] types)
                       throws NotFoundException
Sets exceptions that this method/constructor may throw.

Throws:
NotFoundException

isEmpty

public abstract boolean isEmpty()
Returns true if the body is empty.


setBody

public void setBody(java.lang.String src)
             throws CannotCompileException
Sets a method/constructor body.

Parameters:
src - the source code representing the body. It must be a single statement or block. If it is null, the substituted body does nothing except returning zero or null.
Throws:
CannotCompileException

setBody

public void setBody(java.lang.String src,
                    java.lang.String delegateObj,
                    java.lang.String delegateMethod)
             throws CannotCompileException
Sets a method/constructor body.

Parameters:
src - the source code representing the body. It must be a single statement or block. If it is null, the substituted body does nothing except returning zero or null.
delegateObj - the source text specifying the object that is called on by $proceed().
delegateMethod - the name of the method that is called by $proceed().
Throws:
CannotCompileException

getAttribute

public byte[] getAttribute(java.lang.String name)
Obtains an attribute with the given name. If that attribute is not found in the class file, this method returns null.

Note that an attribute is a data block specified by the class file format. It is not an annotation. See AttributeInfo.

Specified by:
getAttribute in class CtMember
Parameters:
name - attribute name

setAttribute

public void setAttribute(java.lang.String name,
                         byte[] data)
Adds an attribute. The attribute is saved in the class file.

Note that an attribute is a data block specified by the class file format. It is not an annotation. See AttributeInfo.

Specified by:
setAttribute in class CtMember
Parameters:
name - attribute name
data - attribute value

useCflow

public void useCflow(java.lang.String name)
              throws CannotCompileException
Declares to use $cflow for this method/constructor. If $cflow is used, the class files modified with Javassist requires a support class javassist.runtime.Cflow at runtime (other Javassist classes are not required at runtime).

Every $cflow variable is given a unique name. For example, if the given name is "Point.paint", then the variable is indicated by $cflow(Point.paint).

Parameters:
name - $cflow name. It can include alphabets, numbers, _, $, and . (dot).
Throws:
CannotCompileException
See Also:
Cflow

addLocalVariable

public void addLocalVariable(java.lang.String name,
                             CtClass type)
                      throws CannotCompileException
Declares a new local variable. The scope of this variable is the whole method body. The initial value of that variable is not set. The declared variable can be accessed in the code snippet inserted by insertBefore(), insertAfter(), etc.

If the second parameter asFinally to insertAfter() is true, the declared local variable is not visible from the code inserted by insertAfter().

Parameters:
name - the name of the variable
type - the type of the variable
Throws:
CannotCompileException
See Also:
insertBefore(String), insertAfter(String)

instrument

public void instrument(CodeConverter converter)
                throws CannotCompileException
Modifies the method/constructor body.

Parameters:
converter - specifies how to modify.
Throws:
CannotCompileException

instrument

public void instrument(ExprEditor editor)
                throws CannotCompileException
Modifies the method/constructor body.

Parameters:
editor - specifies how to modify.
Throws:
CannotCompileException

insertBefore

public void insertBefore(java.lang.String src)
                  throws CannotCompileException
Inserts bytecode at the beginning of the body.

If this object represents a constructor, the bytecode is inserted before a constructor in the super class or this class is called. Therefore, the inserted bytecode is subject to constraints described in Section 4.8.2 of The Java Virtual Machine Specification (2nd ed). For example, it cannot access instance fields or methods although it may assign a value to an instance field directly declared in this class. Accessing static fields and methods is allowed. Use insertBeforeBody() in CtConstructor.

Parameters:
src - the source code representing the inserted bytecode. It must be a single statement or block.
Throws:
CannotCompileException
See Also:
CtConstructor.insertBeforeBody(String)

insertAfter

public void insertAfter(java.lang.String src)
                 throws CannotCompileException
Inserts bytecode at the end of the body. The bytecode is inserted just before every return insturction. It is not executed when an exception is thrown.

Parameters:
src - the source code representing the inserted bytecode. It must be a single statement or block.
Throws:
CannotCompileException

insertAfter

public void insertAfter(java.lang.String src,
                        boolean asFinally)
                 throws CannotCompileException
Inserts bytecode at the end of the body. The bytecode is inserted just before every return insturction.

Parameters:
src - the source code representing the inserted bytecode. It must be a single statement or block.
asFinally - true if the inserted bytecode 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

addCatch

public void addCatch(java.lang.String src,
                     CtClass exceptionType)
              throws CannotCompileException
Adds a catch clause that handles an exception thrown in the body. The catch clause must end with a return or throw statement.

Parameters:
src - the source code representing the catch clause. It must be a single statement or block.
exceptionType - the type of the exception handled by the catch clause.
Throws:
CannotCompileException

addCatch

public void addCatch(java.lang.String src,
                     CtClass exceptionType,
                     java.lang.String exceptionName)
              throws CannotCompileException
Adds a catch clause that handles an exception thrown in the body. The catch clause must end with a return or throw statement.

Parameters:
src - the source code representing the catch clause. It must be a single statement or block.
exceptionType - the type of the exception handled by the catch clause.
exceptionName - the name of the variable containing the caught exception, for example, $e.
Throws:
CannotCompileException

insertAt

public int insertAt(int lineNum,
                    java.lang.String src)
             throws CannotCompileException
Inserts bytecode at the specified line in the body. It is equivalent to:
insertAt(lineNum, true, src)
See this method as well.

Parameters:
lineNum - the line number. The bytecode is inserted at the beginning of the code at the line specified by this line number.
src - the source code representing the inserted bytecode. It must be a single statement or block.
Returns:
the line number at which the bytecode has been inserted.
Throws:
CannotCompileException
See Also:
insertAt(int,boolean,String)

insertAt

public int insertAt(int lineNum,
                    boolean modify,
                    java.lang.String src)
             throws CannotCompileException
Inserts bytecode at the specified line in the body.

If there is not a statement at the specified line, the bytecode might be inserted at the line including the first statement after that line specified. For example, if there is only a closing brace at that line, the bytecode would be inserted at another line below. To know exactly where the bytecode will be inserted, call with modify set to false.

Parameters:
lineNum - the line number. The bytecode is inserted at the beginning of the code at the line specified by this line number.
modify - if false, this method does not insert the bytecode. It instead only returns the line number at which the bytecode would be inserted.
src - the source code representing the inserted bytecode. It must be a single statement or block. If modify is false, the value of src can be null.
Returns:
the line number at which the bytecode has been inserted.
Throws:
CannotCompileException


Javassist, a Java-bytecode translator toolkit.
Copyright (C) 1999-2006 Shigeru Chiba. All Rights Reserved.