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: 749956 $
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 @SuppressWarnings("unchecked")
056 protected <T> T getBody(Class<T> type, Object body) {
057 Exchange e = getExchange();
058 if (e != null) {
059 CamelContext camelContext = e.getContext();
060 if (camelContext != null) {
061 boolean tryConvert = true;
062 TypeConverter converter = camelContext.getTypeConverter();
063 // if its the default type converter then use a performance shortcut to check if it can convert it
064 // this is faster than getting throwing and catching NoTypeConversionAvailableException
065 // the StreamCachingInterceptor will attempt to convert the payload to a StremCache for caching purpose
066 // so we get invoked on each node the exchange passes. So this is a little performance optimization
067 // to avoid the excessive exception handling
068 if (body != null && converter instanceof DefaultTypeConverter) {
069 DefaultTypeConverter defaultTypeConverter = (DefaultTypeConverter) converter;
070 // we can only check if there is no converter meaning we have tried to convert it beforehand
071 // and then knows for sure there is no converter possible
072 tryConvert = !defaultTypeConverter.hasNoConverterFor(type, body.getClass());
073 }
074 if (tryConvert) {
075 try {
076 // lets first try converting the body itself first
077 // as for some types like InputStream v Reader its more efficient to do the transformation
078 // from the body itself as its got efficient implementations of them, before trying the
079 // message
080 return converter.convertTo(type, e, body);
081 } catch (NoTypeConversionAvailableException ex) {
082 // ignore
083 }
084 }
085 // fallback to the message itself
086 return converter.convertTo(type, this);
087 }
088 }
089 return (T)getBody();
090 }
091
092 public void setBody(Object body) {
093 this.body = body;
094 }
095
096 public <T> void setBody(Object value, Class<T> type) {
097 Exchange e = getExchange();
098 if (e != null) {
099 T v = e.getContext().getTypeConverter().convertTo(type, e, value);
100 if (v != null) {
101 value = v;
102 }
103 }
104 setBody(value);
105 }
106
107 public Message copy() {
108 Message answer = newInstance();
109 answer.copyFrom(this);
110 return answer;
111 }
112
113 public void copyFrom(Message that) {
114 setMessageId(that.getMessageId());
115 setBody(that.getBody());
116 getHeaders().putAll(that.getHeaders());
117 getAttachments().putAll(that.getAttachments());
118 }
119
120 public Exchange getExchange() {
121 return exchange;
122 }
123
124 public void setExchange(Exchange exchange) {
125 this.exchange = exchange;
126 }
127
128 /**
129 * Returns a new instance
130 */
131 public abstract Message newInstance();
132
133 /**
134 * A factory method to allow a provider to lazily create the message body
135 * for inbound messages from other sources
136 *
137 * @return the value of the message body or null if there is no value
138 * available
139 */
140 protected Object createBody() {
141 return null;
142 }
143
144 public String getMessageId() {
145 if (messageId == null) {
146 messageId = createMessageId();
147 }
148 return this.messageId;
149 }
150
151 public void setMessageId(String messageId) {
152 this.messageId = messageId;
153 }
154
155 /**
156 * Lets allow implementations to auto-create a messageId
157 */
158 protected String createMessageId() {
159 return DEFALT_ID_GENERATOR.generateId();
160 }
161 }