http://aopalliance.sourceforge.net: AOP Alliance
  • Public Domain 
package org.aopalliance.intercept;


Intercepts the construction of a new object.

The user should implement the construct(ConstructorInvocation) method to modify the original behavior. E.g. the following class implements a singleton interceptor (allows only one unique instance for the intercepted class): 
class DebuggingInterceptor implements ConstructorInterceptor {
  Object instance=null;
  Object construct(ConstructorInvocation i) throws Throwable {
    if(instance==null) {
      return instance=i.proceed();
    } else {
      throw new Exception("singleton does not allow multiple instance");
    }
  }
}

 
/**
 * Intercepts the construction of a new object.
 *
 * <p>The user should implement the {@link
 * #construct(ConstructorInvocation)} method to modify the original
 * behavior. E.g. the following class implements a singleton
 * interceptor (allows only one unique instance for the intercepted
 * class):
 *
 * <pre class=code>
 * class DebuggingInterceptor implements ConstructorInterceptor {
 *   Object instance=null;
 *
 *   Object construct(ConstructorInvocation i) throws Throwable {
 *     if(instance==null) {
 *       return instance=i.proceed();
 *     } else {
 *       throw new Exception("singleton does not allow multiple instance");
 *     }
 *   }
 * }
 * </pre> */

public interface ConstructorInterceptor extends Interceptor
{
    
Implement this method to perform extra treatments before and after the consrution of a new object. Polite implementations would certainly like to invoke Joinpoint.proceed(). 
Params:
  • invocation – the construction joinpoint
Throws:
  • Throwable – if the interceptors or the
target-object throws an exception.
Returns:the newly created object, which is also the result of the call to Joinpoint.proceed(), might be replaced by the interceptor.
/**
     * Implement this method to perform extra treatments before and
     * after the consrution of a new object. Polite implementations
     * would certainly like to invoke {@link Joinpoint#proceed()}.
     *
     * @param invocation the construction joinpoint
     * @return the newly created object, which is also the result of
     * the call to {@link Joinpoint#proceed()}, might be replaced by
     * the interceptor.
     *
     * @throws Throwable if the interceptors or the
     * target-object throws an exception.  */
    Object construct(ConstructorInvocation invocation) throws Throwable;
}