001 /** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.camel.util; 018 019 import java.util.ArrayList; 020 import java.util.List; 021 022 import org.apache.camel.AsyncCallback; 023 import org.apache.camel.AsyncProcessor; 024 import org.apache.camel.DelegateProcessor; 025 import org.apache.camel.Exchange; 026 import org.apache.camel.Navigate; 027 import org.apache.camel.Processor; 028 import org.apache.camel.Service; 029 030 /** 031 * A simple converter that can convert any {@link Processor} to an {@link AsyncProcessor}. 032 * Processing will still occur synchronously but it will provide the required 033 * notifications that the caller expects. 034 * 035 * @version 036 */ 037 public final class AsyncProcessorConverterHelper { 038 039 private AsyncProcessorConverterHelper() { 040 // Helper class 041 } 042 043 /** 044 * Creates a {@link AsyncProcessor} that delegates to the given processor. 045 * It is important that this implements {@link DelegateProcessor} 046 */ 047 private static final class ProcessorToAsyncProcessorBridge implements DelegateProcessor, AsyncProcessor, Navigate<Processor>, Service { 048 protected Processor processor; 049 050 private ProcessorToAsyncProcessorBridge(Processor processor) { 051 this.processor = processor; 052 } 053 054 public boolean process(Exchange exchange, AsyncCallback callback) { 055 if (processor == null) { 056 // no processor then we are done 057 callback.done(true); 058 return true; 059 } 060 try { 061 processor.process(exchange); 062 } catch (Throwable e) { 063 // must catch throwable so we catch all 064 exchange.setException(e); 065 } finally { 066 // we are bridging a sync processor as async so callback with true 067 callback.done(true); 068 } 069 return true; 070 } 071 072 @Override 073 public String toString() { 074 if (processor != null) { 075 return processor.toString(); 076 } else { 077 return "Processor is null"; 078 } 079 } 080 081 public void process(Exchange exchange) throws Exception { 082 processNext(exchange); 083 } 084 085 protected void processNext(Exchange exchange) throws Exception { 086 if (processor != null) { 087 processor.process(exchange); 088 } 089 } 090 091 public void start() throws Exception { 092 ServiceHelper.startServices(processor); 093 } 094 095 public void stop() throws Exception { 096 ServiceHelper.stopServices(processor); 097 } 098 099 public boolean hasNext() { 100 return processor != null; 101 } 102 103 public List<Processor> next() { 104 if (!hasNext()) { 105 return null; 106 } 107 List<Processor> answer = new ArrayList<Processor>(1); 108 answer.add(processor); 109 return answer; 110 } 111 112 @Override 113 public Processor getProcessor() { 114 return processor; 115 } 116 } 117 118 public static AsyncProcessor convert(Processor value) { 119 if (value instanceof AsyncProcessor) { 120 return (AsyncProcessor)value; 121 } 122 return new ProcessorToAsyncProcessorBridge(value); 123 } 124 }