camel-core/src/main/java/org/apache/camel/impl/BridgeExceptionHandlerToErrorHandler.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.camel.impl;

import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.spi.ExceptionHandler;
import org.apache.camel.spi.UnitOfWork;
import org.apache.camel.support.LoggingExceptionHandler;
import org.apache.camel.util.UnitOfWorkHelper;

/**
 * An {@link ExceptionHandler} that uses the {@link DefaultConsumer} to
 * process the caused exception to send the message into the Camel routing engine
 * which allows to let the routing engine handle the exception.
 * <p/>
 * An endpoint can be configured with <tt>consumer.bridgeErrorHandler=true</tt> in the URI
 * to enable this {@link BridgeExceptionHandlerToErrorHandler} on the consumer.
 * The consumer must extend the {@link DefaultConsumer}, to support this, if not an
 * {@link IllegalArgumentException} is thrown upon startup.
 * <p/>
 * <b>Notice:</b> When using this bridging error handler, then interceptors, onCompletions
 * does <b>not</b> apply. The {@link Exchange} is processed directly by the Camel
 * error handler, and does not allow prior actions such as interceptors, onCompletion
 * to take action.
 */
public class BridgeExceptionHandlerToErrorHandler implements ExceptionHandler {

    private final LoggingExceptionHandler fallback;
    private final DefaultConsumer consumer;
    private final Processor bridge;

    public BridgeExceptionHandlerToErrorHandler(DefaultConsumer consumer) {
        this.consumer = consumer;
        this.fallback = new LoggingExceptionHandler(consumer.getEndpoint().getCamelContext(), consumer.getClass());
        this.bridge = consumer.getProcessor();
    }

    @Override
    public void handleException(Throwable exception) {
        handleException(null, exception);
    }

    @Override
    public void handleException(String message, Throwable exception) {
        handleException(message, null, exception);
    }

    @Override
    public void handleException(String message, Exchange exchange, Throwable exception) {
        if (exchange == null) {
            exchange = consumer.getEndpoint().createExchange();
        }

        // set the caused exception
        exchange.setException(exception);
        // and the message
        exchange.getIn().setBody(message);
        // and mark as redelivery exhausted as we cannot do redeliveries
        exchange.setProperty(Exchange.REDELIVERY_EXHAUSTED, Boolean.TRUE);

        // wrap in UoW
        UnitOfWork uow = null;
        try {
            uow = consumer.createUoW(exchange);
            bridge.process(exchange);
        } catch (Exception e) {
            fallback.handleException("Error handling exception " + exception.getMessage(), exchange, e);
        } finally {
            UnitOfWorkHelper.doneUow(uow, exchange);
        }
    }
}