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: 789087 $ 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 // eager same instance type test to avoid the overhead of invoking the type converter 062 // if already same type 063 if (type.isInstance(body)) { 064 return type.cast(body); 065 } 066 067 Exchange e = getExchange(); 068 if (e != null) { 069 TypeConverter converter = e.getContext().getTypeConverter(); 070 071 // lets first try converting the body itself first 072 // as for some types like InputStream v Reader its more efficient to do the transformation 073 // from the body itself as its got efficient implementations of them, before trying the 074 // message 075 T answer = converter.convertTo(type, getExchange(), body); 076 if (answer != null) { 077 return answer; 078 } 079 080 // fallback to the message itself (e.g. used in camel-http) 081 answer = converter.convertTo(type, getExchange(), this); 082 if (answer != null) { 083 return answer; 084 } 085 } 086 087 // not possible to convert 088 return null; 089 } 090 091 public <T> T getMandatoryBody(Class<T> type) throws InvalidPayloadException { 092 // eager same instance type test to avoid the overhead of invoking the type converter 093 // if already same type 094 if (type.isInstance(body)) { 095 return type.cast(body); 096 } 097 098 Exchange e = getExchange(); 099 if (e != null) { 100 TypeConverter converter = e.getContext().getTypeConverter(); 101 try { 102 return converter.mandatoryConvertTo(type, e, getBody()); 103 } catch (Exception cause) { 104 throw new InvalidPayloadException(e, type, this, cause); 105 } 106 } 107 throw new InvalidPayloadException(e, type, this); 108 } 109 110 public void setBody(Object body) { 111 this.body = body; 112 } 113 114 public <T> void setBody(Object value, Class<T> type) { 115 Exchange e = getExchange(); 116 if (e != null) { 117 T v = e.getContext().getTypeConverter().convertTo(type, e, value); 118 if (v != null) { 119 value = v; 120 } 121 } 122 setBody(value); 123 } 124 125 public Message copy() { 126 Message answer = newInstance(); 127 answer.copyFrom(this); 128 return answer; 129 } 130 131 public void copyFrom(Message that) { 132 setMessageId(that.getMessageId()); 133 setBody(that.getBody()); 134 getHeaders().putAll(that.getHeaders()); 135 getAttachments().putAll(that.getAttachments()); 136 } 137 138 public Exchange getExchange() { 139 return exchange; 140 } 141 142 public void setExchange(Exchange exchange) { 143 this.exchange = exchange; 144 } 145 146 /** 147 * Returns a new instance 148 */ 149 public abstract Message newInstance(); 150 151 /** 152 * A factory method to allow a provider to lazily create the message body 153 * for inbound messages from other sources 154 * 155 * @return the value of the message body or null if there is no value 156 * available 157 */ 158 protected Object createBody() { 159 return null; 160 } 161 162 public String getMessageId() { 163 if (messageId == null) { 164 messageId = createMessageId(); 165 } 166 return this.messageId; 167 } 168 169 public void setMessageId(String messageId) { 170 this.messageId = messageId; 171 } 172 173 /** 174 * Lets allow implementations to auto-create a messageId 175 */ 176 protected String createMessageId() { 177 return DEFALT_ID_GENERATOR.generateId(); 178 } 179 }