ExceptionUtils.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.deltaspike.core.util;

import javax.enterprise.inject.Typed;
import java.lang.reflect.Constructor;

@Typed()
public abstract class ExceptionUtils
{
    private ExceptionUtils()
    {
        // prevent instantiation
    }

    public static RuntimeException throwAsRuntimeException(Throwable throwable)
    {
        //Attention: helper which allows to use a trick to throw
        // a catched checked exception without a wrapping exception
        new ExceptionHelper<RuntimeException>().throwException(throwable);
        return null; //not needed due to the helper trick, but it's easier for using it
    }

    public static void changeAndThrowException(Throwable throwable, String customMessage)
    {
        Throwable newThrowable = createNewException(throwable, customMessage);
        //Attention: helper which allows to use a trick to throw a cached checked exception without a wrapping exception
        new ExceptionHelper<RuntimeException>().throwException(newThrowable);
    }

    private static Throwable createNewException(Throwable throwable, String message)
    {
        Class<? extends Throwable> throwableClass = throwable.getClass();

        try
        {
            Constructor<? extends Throwable> constructor = throwableClass.getDeclaredConstructor(String.class);
            constructor.setAccessible(true);
            Throwable result = constructor.newInstance(message);
            result.initCause(throwable.getCause());
            return result;
        }
        catch (Exception e)
        {
            //use the original exception if there is any issue
            return throwable;
        }
    }

    @SuppressWarnings({ "unchecked" })
    private static class ExceptionHelper<T extends Throwable>
    {
        private void throwException(Throwable exception) throws T
        {
            try
            {
                //exception-type is only checked at compile-time
                throw (T) exception;
            }
            catch (ClassCastException e)
            {
                //doesn't happen with existing JVMs! - if that changes the local ClassCastException needs to be ignored
                //-> throw original exception
                if (e.getStackTrace()[0].toString().contains(getClass().getName()))
                {
                    if (exception instanceof RuntimeException)
                    {
                        throw (RuntimeException) exception;
                    }
                    throw new RuntimeException(exception);
                }
                //if the exception to throw is a ClassCastException, throw it
                throw e;
            }
        }
    }
}