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 }