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net.sf.cglib.proxy
public class: Enhancer [javadoc | source]
java.lang.Object
   net.sf.cglib.core.AbstractClassGenerator
      net.sf.cglib.proxy.Enhancer

All Implemented Interfaces:
    ClassGenerator

Generates dynamic subclasses to enable method interception. This class started as a substitute for the standard Dynamic Proxy support included with JDK 1.3, but one that allowed the proxies to extend a concrete base class, in addition to implementing interfaces. The dynamically generated subclasses override the non-final methods of the superclass and have hooks which callback to user-defined interceptor implementations.

The original and most general callback type is the MethodInterceptor , which in AOP terms enables "around advice"--that is, you can invoke custom code both before and after the invocation of the "super" method. In addition you can modify the arguments before calling the super method, or not call it at all.

Although MethodInterceptor is generic enough to meet any interception need, it is often overkill. For simplicity and performance, additional specialized callback types, such as LazyLoader are also available. Often a single callback will be used per enhanced class, but you can control which callback is used on a per-method basis with a CallbackFilter .

The most common uses of this class are embodied in the static helper methods. For advanced needs, such as customizing the ClassLoader to use, you should create a new instance of Enhancer. Other classes within CGLIB follow a similar pattern.

All enhanced objects implement the Factory interface, unless #setUseFactory is used to explicitly disable this feature. The Factory interface provides an API to change the callbacks of an existing object, as well as a faster and easier way to create new instances of the same type.

For an almost drop-in replacement for java.lang.reflect.Proxy, see the Proxy class.
Nested Class Summary:
public interface  Enhancer.EnhancerKey  Internal interface, only public due to ClassLoader issues. 
Constructor:
 public Enhancer() 
Method from net.sf.cglib.proxy.Enhancer Summary:
create,   create,   create,   create,   create,   createClass,   filterConstructors,   firstInstance,   generateClass,   getDefaultClassLoader,   getMethods,   isEnhanced,   nextInstance,   registerCallbacks,   registerStaticCallbacks,   setCallback,   setCallbackFilter,   setCallbackType,   setCallbackTypes,   setCallbacks,   setInterceptDuringConstruction,   setInterfaces,   setSerialVersionUID,   setSuperclass,   setUseFactory
Methods from net.sf.cglib.core.AbstractClassGenerator:
create,   firstInstance,   getAttemptLoad,   getClassLoader,   getClassName,   getCurrent,   getDefaultClassLoader,   getNamingPolicy,   getStrategy,   getUseCache,   nextInstance,   setAttemptLoad,   setClassLoader,   setNamePrefix,   setNamingPolicy,   setStrategy,   setUseCache
Methods from java.lang.Object:
equals,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
Method from net.sf.cglib.proxy.Enhancer Detail:
 public Object create() 
    Generate a new class if necessary and uses the specified callbacks (if any) to create a new object instance. Uses the no-arg constructor of the superclass.
 public Object create(Class[] argumentTypes,
    Object[] arguments) 
    Generate a new class if necessary and uses the specified callbacks (if any) to create a new object instance. Uses the constructor of the superclass matching the argumentTypes parameter, with the given arguments.
 public static Object create(Class type,
    Callback callback) 
    Helper method to create an intercepted object. For finer control over the generated instance, use a new instance of Enhancer instead of this static method.
 public static Object create(Class superclass,
    Class[] interfaces,
    Callback callback) 
    Helper method to create an intercepted object. For finer control over the generated instance, use a new instance of Enhancer instead of this static method.
 public static Object create(Class superclass,
    Class[] interfaces,
    CallbackFilter filter,
    Callback[] callbacks) 
    Helper method to create an intercepted object. For finer control over the generated instance, use a new instance of Enhancer instead of this static method.
 public Class createClass() 
    Generate a new class if necessary and return it without creating a new instance. This ignores any callbacks that have been set. To create a new instance you will have to use reflection, and methods called during the constructor will not be intercepted. To avoid this problem, use the multi-arg create method.
 protected  void filterConstructors(Class sc,
    List constructors) 
    Filter the list of constructors from the superclass. The constructors which remain will be included in the generated class. The default implementation is to filter out all private constructors, but subclasses may extend Enhancer to override this behavior.
 protected Object firstInstance(Class type) throws Exception 
 public  void generateClass(ClassVisitor v) throws Exception 
 protected ClassLoader getDefaultClassLoader() 
 public static  void getMethods(Class superclass,
    Class[] interfaces,
    List methods) 
    Finds all of the methods that will be extended by an Enhancer-generated class using the specified superclass and interfaces. This can be useful in building a list of Callback objects. The methods are added to the end of the given list. Due to the subclassing nature of the classes generated by Enhancer, the methods are guaranteed to be non-static, non-final, and non-private. Each method signature will only occur once, even if it occurs in multiple classes.
 public static boolean isEnhanced(Class type) 
    Determine if a class was generated using Enhancer.
 protected Object nextInstance(Object instance) 
 public static  void registerCallbacks(Class generatedClass,
    Callback[] callbacks) 
    Call this method to register the Callback array to use before creating a new instance of the generated class via reflection. If you are using an instance of Enhancer or the Factory interface to create new instances, this method is unnecessary. Its primary use is for when you want to cache and reuse a generated class yourself, and the generated class does not implement the Factory interface.

    Note that this method only registers the callbacks on the current thread. If you want to register callbacks for instances created by multiple threads, use #registerStaticCallbacks .

    The registered callbacks are overwritten and subsequently cleared when calling any of the create methods (such as #create ), or any Factory newInstance method. Otherwise they are not cleared, and you should be careful to set them back to null after creating new instances via reflection if memory leakage is a concern.

 public static  void registerStaticCallbacks(Class generatedClass,
    Callback[] callbacks) 
    Similar to #registerCallbacks , but suitable for use when multiple threads will be creating instances of the generated class. The thread-level callbacks will always override the static callbacks. Static callbacks are never cleared.
 public  void setCallback(Callback callback) 
 public  void setCallbackFilter(CallbackFilter filter) 
    Set the CallbackFilter used to map the generated class' methods to a particular callback index. New object instances will always use the same mapping, but may use different actual callback objects.
 public  void setCallbackType(Class callbackType) 
    Set the single type of Callback to use. This may be used instead of #setCallback when calling #createClass , since it may not be possible to have an array of actual callback instances.
 public  void setCallbackTypes(Class[] callbackTypes) 
    Set the array of callback types to use. This may be used instead of #setCallbacks when calling #createClass , since it may not be possible to have an array of actual callback instances. You must use a CallbackFilter to specify the index into this array for each method in the proxied class.
 public  void setCallbacks(Callback[] callbacks) 
    Set the array of callbacks to use. Ignored if you use #createClass . You must use a CallbackFilter to specify the index into this array for each method in the proxied class.
 public  void setInterceptDuringConstruction(boolean interceptDuringConstruction) 
    Set whether methods called from within the proxy's constructer will be intercepted. The default value is true. Unintercepted methods will call the method of the proxy's base class, if it exists.
 public  void setInterfaces(Class[] interfaces) 
    Set the interfaces to implement. The Factory interface will always be implemented regardless of what is specified here.
 public  void setSerialVersionUID(Long sUID) 
    Insert a static serialVersionUID field into the generated class.
 public  void setSuperclass(Class superclass) 
    Set the class which the generated class will extend. As a convenience, if the supplied superclass is actually an interface, setInterfaces will be called with the appropriate argument instead. A non-interface argument must not be declared as final, and must have an accessible constructor.
 public  void setUseFactory(boolean useFactory) 
    Set whether the enhanced object instances should implement the Factory interface. This was added for tools that need for proxies to be more indistinguishable from their targets. Also, in some cases it may be necessary to disable the Factory interface to prevent code from changing the underlying callbacks.