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.impl; 018 019 import org.apache.camel.CamelContext; 020 import org.apache.camel.Exchange; 021 import org.apache.camel.Message; 022 import org.apache.camel.NoTypeConversionAvailableException; 023 import org.apache.camel.TypeConverter; 024 import org.apache.camel.impl.converter.DefaultTypeConverter; 025 import org.apache.camel.util.UuidGenerator; 026 027 /** 028 * A base class for implementation inheritence providing the core 029 * {@link Message} body handling features but letting the derived class deal 030 * with headers. 031 * 032 * Unless a specific provider wishes to do something particularly clever with 033 * headers you probably want to just derive from {@link DefaultMessage} 034 * 035 * @version $Revision: 749962 $ 036 */ 037 public abstract class MessageSupport implements Message { 038 private static final UuidGenerator DEFALT_ID_GENERATOR = new UuidGenerator(); 039 private Exchange exchange; 040 private Object body; 041 private String messageId; 042 043 public Object getBody() { 044 if (body == null) { 045 body = createBody(); 046 } 047 return body; 048 } 049 050 @SuppressWarnings({"unchecked" }) 051 public <T> T getBody(Class<T> type) { 052 return getBody(type, getBody()); 053 } 054 055 protected <T> T getBody(Class<T> type, Object body) { 056 Exchange e = getExchange(); 057 if (e != null) { 058 CamelContext camelContext = e.getContext(); 059 if (camelContext != null) { 060 boolean tryConvert = true; 061 TypeConverter converter = camelContext.getTypeConverter(); 062 // if its the default type converter then use a performance shortcut to check if it can convert it 063 // this is faster than getting throwing and catching NoTypeConversionAvailableException 064 // the StreamCachingInterceptor will attempt to convert the payload to a StremCache for caching purpose 065 // so we get invoked on each node the exchange passes. So this is a little performance optimization 066 // to avoid the excessive exception handling 067 if (body != null && converter instanceof DefaultTypeConverter) { 068 DefaultTypeConverter defaultTypeConverter = (DefaultTypeConverter) converter; 069 // we can only check if there is no converter meaning we have tried to convert it beforehand 070 // and then knows for sure there is no converter possible 071 tryConvert = !defaultTypeConverter.hasNoConverterFor(type, body.getClass()); 072 } 073 if (tryConvert) { 074 try { 075 // lets first try converting the body itself first 076 // as for some types like InputStream v Reader its more efficient to do the transformation 077 // from the body itself as its got efficient implementations of them, before trying the 078 // message 079 return converter.convertTo(type, e, body); 080 } catch (NoTypeConversionAvailableException ex) { 081 // ignore 082 } 083 } 084 // fallback to the message itself 085 return converter.convertTo(type, this); 086 } 087 } 088 return (T)getBody(); 089 } 090 091 public void setBody(Object body) { 092 this.body = body; 093 } 094 095 public <T> void setBody(Object value, Class<T> type) { 096 Exchange e = getExchange(); 097 if (e != null) { 098 T v = e.getContext().getTypeConverter().convertTo(type, e, value); 099 if (v != null) { 100 value = v; 101 } 102 } 103 setBody(value); 104 } 105 106 public Message copy() { 107 Message answer = newInstance(); 108 answer.copyFrom(this); 109 return answer; 110 } 111 112 public void copyFrom(Message that) { 113 setMessageId(that.getMessageId()); 114 setBody(that.getBody()); 115 getHeaders().putAll(that.getHeaders()); 116 getAttachments().putAll(that.getAttachments()); 117 } 118 119 public Exchange getExchange() { 120 return exchange; 121 } 122 123 public void setExchange(Exchange exchange) { 124 this.exchange = exchange; 125 } 126 127 /** 128 * Returns a new instance 129 */ 130 public abstract Message newInstance(); 131 132 /** 133 * A factory method to allow a provider to lazily create the message body 134 * for inbound messages from other sources 135 * 136 * @return the value of the message body or null if there is no value 137 * available 138 */ 139 protected Object createBody() { 140 return null; 141 } 142 143 public String getMessageId() { 144 if (messageId == null) { 145 messageId = createMessageId(); 146 } 147 return this.messageId; 148 } 149 150 public void setMessageId(String messageId) { 151 this.messageId = messageId; 152 } 153 154 /** 155 * Lets allow implementations to auto-create a messageId 156 */ 157 protected String createMessageId() { 158 return DEFALT_ID_GENERATOR.generateId(); 159 } 160 }