mockit.internal.expectations.mocking.InstanceFactory Maven / Gradle / Ivy

/*
 * Copyright (c) 2006 JMockit developers
 * This file is subject to the terms of the MIT license (see LICENSE.txt).
 */
package mockit.internal.expectations.mocking;

import java.lang.reflect.*;
import javax.annotation.*;

import mockit.internal.util.*;

import sun.reflect.ReflectionFactory;

/**
 * Factory for the creation of new mocked instances, and for obtaining/clearing the last instance created.
 * There are separate subclasses dedicated to mocked interfaces and mocked classes.
 */
public abstract class InstanceFactory
{
   @SuppressWarnings("UseOfSunClasses")
   private static final ReflectionFactory REFLECTION_FACTORY = ReflectionFactory.getReflectionFactory();
   private static final Constructor OBJECT_CONSTRUCTOR;
   static {
      try { OBJECT_CONSTRUCTOR = Object.class.getConstructor(); }
      catch (NoSuchMethodException e) { throw new RuntimeException(e); }
   }

   @Nonnull final Class concreteClass;
   @Nullable Object lastInstance;

   InstanceFactory(@Nonnull Class concreteClass) { this.concreteClass = concreteClass; }

   @Nonnull
   final  T newUninitializedConcreteClassInstance() {
      try {
         Constructor fakeConstructor = REFLECTION_FACTORY.newConstructorForSerialization(concreteClass, OBJECT_CONSTRUCTOR);

         if (fakeConstructor == null) { // can happen on Java 9
            //noinspection ConstantConditions
            return null;
         }

         @SuppressWarnings("unchecked") T newInstance = (T) fakeConstructor.newInstance();
         return newInstance;
      }
      catch (NoClassDefFoundError | ExceptionInInitializerError e) {
         StackTrace.filterStackTrace(e);
         e.printStackTrace();
         throw e;
      }
      catch (InstantiationException | IllegalAccessException e) { throw new RuntimeException(e); }
      catch (InvocationTargetException e) { throw new RuntimeException(e.getCause()); }
   }

   @Nonnull public abstract Object create();

   @Nullable public final Object getLastInstance() { return lastInstance; }
   public abstract void clearLastInstance();

   static final class InterfaceInstanceFactory extends InstanceFactory {
      @Nullable private Object emptyProxy;

      InterfaceInstanceFactory(@Nonnull Object emptyProxy) {
         super(emptyProxy.getClass());
         this.emptyProxy = emptyProxy;
      }

      @Nonnull @Override
      public Object create() {
         if (emptyProxy == null) {
            emptyProxy = newUninitializedConcreteClassInstance();
         }

         lastInstance = emptyProxy;
         return emptyProxy;
      }

      @Override
      public void clearLastInstance() {
         emptyProxy = null;
         lastInstance = null;
      }
   }

   static final class ClassInstanceFactory extends InstanceFactory {
      ClassInstanceFactory(@Nonnull Class concreteClass) { super(concreteClass); }

      @Override @Nonnull
      public Object create() {
         lastInstance = newUninitializedConcreteClassInstance();
         return lastInstance;
      }

      @Override
      public void clearLastInstance() { lastInstance = null; }
   }
}