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.Exchange;
020 import org.apache.camel.InvalidPayloadException;
021 import org.apache.camel.Message;
022 import org.apache.camel.TypeConverter;
023 import org.apache.camel.util.UuidGenerator;
024
025 /**
026 * A base class for implementation inheritence providing the core
027 * {@link Message} body handling features but letting the derived class deal
028 * with headers.
029 *
030 * Unless a specific provider wishes to do something particularly clever with
031 * headers you probably want to just derive from {@link DefaultMessage}
032 *
033 * @version $Revision: 755890 $
034 */
035 public abstract class MessageSupport implements Message {
036 private static final UuidGenerator DEFALT_ID_GENERATOR = new UuidGenerator();
037 private Exchange exchange;
038 private Object body;
039 private String messageId;
040
041 public Object getBody() {
042 if (body == null) {
043 body = createBody();
044 }
045 return body;
046 }
047
048 public <T> T getBody(Class<T> type) {
049 return getBody(type, getBody());
050 }
051
052 public Object getMandatoryBody() throws InvalidPayloadException {
053 Object answer = getBody();
054 if (answer == null) {
055 throw new InvalidPayloadException(getExchange(), Object.class, this);
056 }
057 return answer;
058 }
059
060 protected <T> T getBody(Class<T> type, Object body) {
061 Exchange e = getExchange();
062 if (e != null) {
063 TypeConverter converter = e.getContext().getTypeConverter();
064
065 // lets first try converting the body itself first
066 // as for some types like InputStream v Reader its more efficient to do the transformation
067 // from the body itself as its got efficient implementations of them, before trying the
068 // message
069 T answer = converter.convertTo(type, getExchange(), body);
070 if (answer != null) {
071 return answer;
072 }
073 // fallback to the message itself
074 answer = converter.convertTo(type, getExchange(), this);
075 if (answer != null) {
076 return answer;
077 }
078 }
079
080 // not possible to convert
081 return null;
082 }
083
084 public <T> T getMandatoryBody(Class<T> type) throws InvalidPayloadException {
085 Exchange e = getExchange();
086 if (e != null) {
087 TypeConverter converter = e.getContext().getTypeConverter();
088 try {
089 return converter.mandatoryConvertTo(type, e, getBody());
090 } catch (Exception cause) {
091 throw new InvalidPayloadException(e, type, this, cause);
092 }
093 }
094 throw new InvalidPayloadException(e, type, this);
095 }
096
097 public void setBody(Object body) {
098 this.body = body;
099 }
100
101 public <T> void setBody(Object value, Class<T> type) {
102 Exchange e = getExchange();
103 if (e != null) {
104 T v = e.getContext().getTypeConverter().convertTo(type, e, value);
105 if (v != null) {
106 value = v;
107 }
108 }
109 setBody(value);
110 }
111
112 public Message copy() {
113 Message answer = newInstance();
114 answer.copyFrom(this);
115 return answer;
116 }
117
118 public void copyFrom(Message that) {
119 setMessageId(that.getMessageId());
120 setBody(that.getBody());
121 getHeaders().putAll(that.getHeaders());
122 getAttachments().putAll(that.getAttachments());
123 }
124
125 public Exchange getExchange() {
126 return exchange;
127 }
128
129 public void setExchange(Exchange exchange) {
130 this.exchange = exchange;
131 }
132
133 /**
134 * Returns a new instance
135 */
136 public abstract Message newInstance();
137
138 /**
139 * A factory method to allow a provider to lazily create the message body
140 * for inbound messages from other sources
141 *
142 * @return the value of the message body or null if there is no value
143 * available
144 */
145 protected Object createBody() {
146 return null;
147 }
148
149 public String getMessageId() {
150 if (messageId == null) {
151 messageId = createMessageId();
152 }
153 return this.messageId;
154 }
155
156 public void setMessageId(String messageId) {
157 this.messageId = messageId;
158 }
159
160 /**
161 * Lets allow implementations to auto-create a messageId
162 */
163 protected String createMessageId() {
164 return DEFALT_ID_GENERATOR.generateId();
165 }
166 }