ClassFab

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Class

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Deprecated

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org.apache.hivemind.service
Interface ClassFab

public interface ClassFab

Used when fabricating a new class. Represents a wrapper around the Javassist library.

The core concept of Javassist is how method bodies (as well as constructor bodies, etc.) are specified ... as a very Java-like scripting language. The BodyBuilder class is very useful for assembling this method bodies. Details are available at the Javassist home page.

Method bodies look largely like Java. References to java classes must be fully qualified. Several special variables are used:

$0 first parameter, equivalent to this in Java code (and can't be used when creating a static method)
$1, $2, ... actual parameters to the method
$args all the parameters as an Object[]
$r the return type of the method, typically used as return ($r) .... $r is valid with method that return void. This also handles conversions between wrapper types and primitive types.
$w conversion from primitive type to wrapper type, used as ($w) foo() where foo() returns a primitive type and a wrapper type is needed

Method Summary

void addConstructor(java.lang.Class[] parameterTypes, java.lang.Class[] exceptions, java.lang.String body)
          Adds a constructor to the class.

void addField(java.lang.String name, java.lang.Class type)
          Adds a new field with the given name and type.

void addInterface(java.lang.Class interfaceClass)
          Adds the specified interface as an interface implemented by this class.

MethodFab addMethod(int modifiers, MethodSignature signature, java.lang.String body)
          Adds a method.

boolean containsMethod(MethodSignature signature)
          Convenience method for checking whether the fabricated class already contains a method.

java.lang.Class createClass()
          Invoked last to create the class.

MethodFab getMethodFab(MethodSignature signature)
          Returns a previous defined method so that it can be further enhanced (perhaps by adding additional catches, etc.).

Method Detail

addInterface

public void addInterface(java.lang.Class interfaceClass)

Adds the specified interface as an interface implemented by this class.

addField

public void addField(java.lang.String name,
                     java.lang.Class type)

Adds a new field with the given name and type. The field is added as a private field.

containsMethod

public boolean containsMethod(MethodSignature signature)

Convenience method for checking whether the fabricated class already contains a method.

addMethod

public MethodFab addMethod(int modifiers,
                           MethodSignature signature,
                           java.lang.String body)

Adds a method. The method is a public instance method.

getMethodFab

public MethodFab getMethodFab(MethodSignature signature)

Returns a previous defined method so that it can be further enhanced (perhaps by adding additional catches, etc.).

addConstructor

public void addConstructor(java.lang.Class[] parameterTypes,
                           java.lang.Class[] exceptions,
                           java.lang.String body)

Adds a constructor to the class. The constructor will be public.

createClass

public java.lang.Class createClass()

Invoked last to create the class. This will enforce that all abstract methods have been implemented in the (concrete) class.