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: 13620 $ 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 // same instance type 057 if (type.isInstance(body)) { 058 return type.cast(body); 059 } 060 061 Exchange e = getExchange(); 062 if (e != null) { 063 CamelContext camelContext = e.getContext(); 064 if (camelContext != null) { 065 boolean tryConvert = true; 066 TypeConverter converter = camelContext.getTypeConverter(); 067 // if its the default type converter then use a performance shortcut to check if it can convert it 068 // this is faster than getting throwing and catching NoTypeConversionAvailableException 069 // the StreamCachingInterceptor will attempt to convert the payload to a StremCache for caching purpose 070 // so we get invoked on each node the exchange passes. So this is a little performance optimization 071 // to avoid the excessive exception handling 072 if (body != null) { 073 // we can only check if there is no converter meaning we have tried to convert it beforehand 074 // and then knows for sure there is no converter possible 075 tryConvert = !hasNoConverterFor(converter, type, body.getClass()); 076 } 077 if (tryConvert) { 078 try { 079 // lets first try converting the body itself first 080 // as for some types like InputStream v Reader its more efficient to do the transformation 081 // from the body itself as its got efficient implementations of them, before trying the 082 // message 083 return converter.convertTo(type, e, body); 084 } catch (NoTypeConversionAvailableException ex) { 085 // ignore 086 } 087 } 088 089 // fallback to the message itself (e.g. used in camel-http) 090 tryConvert = !hasNoConverterFor(converter, type, this.getClass()); 091 if (tryConvert) { 092 try { 093 return converter.convertTo(type, e, this); 094 } catch (NoTypeConversionAvailableException ex) { 095 // ignore 096 } 097 } 098 } 099 } 100 101 // not possible to convert 102 throw new NoTypeConversionAvailableException(body, type); 103 } 104 105 private boolean hasNoConverterFor(TypeConverter converter, Class toType, Class fromType) { 106 if (converter instanceof DefaultTypeConverter) { 107 DefaultTypeConverter defaultTypeConverter = (DefaultTypeConverter) converter; 108 // we can only check if there is no converter meaning we have tried to convert it beforehand 109 // and then knows for sure there is no converter possible 110 return defaultTypeConverter.hasNoConverterFor(toType, fromType); 111 } 112 return false; 113 } 114 115 public void setBody(Object body) { 116 this.body = body; 117 } 118 119 public <T> void setBody(Object value, Class<T> type) { 120 Exchange e = getExchange(); 121 if (e != null) { 122 T v = e.getContext().getTypeConverter().convertTo(type, e, value); 123 if (v != null) { 124 value = v; 125 } 126 } 127 setBody(value); 128 } 129 130 public Message copy() { 131 Message answer = newInstance(); 132 answer.copyFrom(this); 133 return answer; 134 } 135 136 public void copyFrom(Message that) { 137 setMessageId(that.getMessageId()); 138 setBody(that.getBody()); 139 getHeaders().putAll(that.getHeaders()); 140 getAttachments().putAll(that.getAttachments()); 141 } 142 143 public Exchange getExchange() { 144 return exchange; 145 } 146 147 public void setExchange(Exchange exchange) { 148 this.exchange = exchange; 149 } 150 151 /** 152 * Returns a new instance 153 */ 154 public abstract Message newInstance(); 155 156 /** 157 * A factory method to allow a provider to lazily create the message body 158 * for inbound messages from other sources 159 * 160 * @return the value of the message body or null if there is no value 161 * available 162 */ 163 protected Object createBody() { 164 return null; 165 } 166 167 public String getMessageId() { 168 if (messageId == null) { 169 messageId = createMessageId(); 170 } 171 return this.messageId; 172 } 173 174 public void setMessageId(String messageId) { 175 this.messageId = messageId; 176 } 177 178 /** 179 * Lets allow implementations to auto-create a messageId 180 */ 181 protected String createMessageId() { 182 return DEFALT_ID_GENERATOR.generateId(); 183 } 184 }