java.lang.reflect.InvocationHandler Maven / Gradle / Ivy
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This work corresponds to the API signatures of JSR 219: Foundation
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*/
package java.lang.reflect;
/**
* InvocationHandler is the interface implemented by
* the invocation handler of a proxy instance.
*
*
Each proxy instance has an associated invocation handler.
* When a method is invoked on a proxy instance, the method
* invocation is encoded and dispatched to the invoke
* method of its invocation handler.
*
* @author Peter Jones
* @version 1.5, 00/02/02
* @see Proxy
* @since JDK1.3
*/
public interface InvocationHandler
{
/**
* Processes a method invocation on a proxy instance and returns
* the result. This method will be invoked on an invocation handler
* when a method is invoked on a proxy instance that it is
* associated with.
*
* @param proxy the proxy instance that the method was invoked on
*
* @param method the Method instance corresponding to
* the interface method invoked on the proxy instance. The declaring
* class of the Method object will be the interface that
* the method was declared in, which may be a superinterface of the
* proxy interface that the proxy class inherits the method through.
*
* @param args an array of objects containing the values of the
* arguments passed in the method invocation on the proxy instance,
* or null if interface method takes no arguments.
* Arguments of primitive types are wrapped in instances of the
* appropriate primitive wrapper class, such as
* java.lang.Integer or java.lang.Boolean.
*
* @return the value to return from the method invocation on the
* proxy instance. If the declared return type of the interface
* method is a primitive type, then the value returned by
* this method must be an instance of the corresponding primitive
* wrapper class; otherwise, it must be a type assignable to the
* declared return type. If the value returned by this method is
* null and the interface method's return type is
* primitive, then a NullPointerException will be
* thrown by the method invocation on the proxy instance. If the
* value returned by this method is otherwise not compatible with
* the interface method's declared return type as described above,
* a ClassCastException will be thrown by the method
* invocation on the proxy instance.
*
* @throws Throwable the exception to throw from the method
* invocation on the proxy instance. The exception's type must be
* assignable either to any of the exception types declared in the
* throws clause of the interface method or to the
* unchecked exception types java.lang.RuntimeException
* or java.lang.Error. If a checked exception is
* thrown by this method that is not assignable to any of the
* exception types declared in the throws clause of
* the interface method, then an
* {@link UndeclaredThrowableException} containing the
* exception that was thrown by this method will be thrown by the
* method invocation on the proxy instance.
*
* @see UndeclaredThrowableException
*/
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable;
}