AMQP-277 Add DefaultType to DefaultClassMapper

Permit the use of a JsonMessageConverter when no type information
is provided in the MessageProperties and the type is known.

spring-amqp/src/main/java/org/springframework/amqp/support/converter/DefaultClassMapper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2010 the original author or authors.
+ * Copyright 2002-2012 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
  * the License. You may obtain a copy of the License at
@@ -22,21 +22,37 @@ import org.springframework.beans.factory.InitializingBean;
 import org.springframework.util.ClassUtils;
 
 /**
- * 
+ * Maps to/from JSON using type information in the {@link MessageProperties};
+ * the default name of the message property containing the type is '__TypeId__'.
+ * An optional property {@link #setDefaultType(Class)}
+ * is provided that allows mapping to a statically defined type, if no message property is
+ * found in the message properties.
  * @author Mark Pollack
- * 
+ * @author Gary Russell
+ *
  */
 public class DefaultClassMapper implements ClassMapper, InitializingBean {
 
 	public static final String DEFAULT_CLASSID_FIELD_NAME = "__TypeId__";
 
-	private Map<String, Class<?>> idClassMapping = new HashMap<String, Class<?>>();
+	private volatile Map<String, Class<?>> idClassMapping = new HashMap<String, Class<?>>();
 
-	private Map<Class<?>, String> classIdMapping = new HashMap<Class<?>, String>();
+	private volatile Map<Class<?>, String> classIdMapping = new HashMap<Class<?>, String>();
 
-	private String defaultHashtableTypeId = "Hashtable";
+	private final String defaultHashtableTypeId = "Hashtable";
 
-	private Class<?> defaultHashtableClass = Hashtable.class;
+	private volatile Class<?> defaultHashtableClass = Hashtable.class;
+
+	private volatile Class<?> defaultType;
+
+	/**
+	 * The type returned by {@link #toClass(MessageProperties)} if no type information
+	 * is found in the message properties.
+	 * @param defaultType the defaultType to set
+	 */
+	public void setDefaultType(Class<?> defaultType) {
+		this.defaultType = defaultType;
+	}
 
 	public void setDefaultHashtableClass(Class<?> defaultHashtableClass) {
 		this.defaultHashtableClass = defaultHashtableClass;
@@ -105,9 +121,15 @@ public class DefaultClassMapper implements ClassMapper, InitializingBean {
 			classId = classIdFieldNameValue.toString();
 		}
 		if (classId == null) {
-			throw new MessageConversionException(
-					"failed to convert Message content. Could not resolve "
-							+ getClassIdFieldName() + " in header");
+			if (this.defaultType != null) {
+				return this.defaultType;
+			}
+			else {
+				throw new MessageConversionException(
+						"failed to convert Message content. Could not resolve "
+								+ getClassIdFieldName() + " in header " +
+								"and no defaultType provided");
+			}
 		}
 		return toClass(classId);
 	}

spring-amqp/src/test/java/org/springframework/amqp/support/converter/DefaultClassMapperTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2012 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
  * the License. You may obtain a copy of the License at
@@ -14,6 +14,7 @@ package org.springframework.amqp.support.converter;
 
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertThat;
 import static org.junit.matchers.JUnitMatchers.containsString;
 import static org.mockito.BDDMockito.given;
@@ -28,15 +29,18 @@ import org.junit.runner.RunWith;
 import org.mockito.Spy;
 import org.mockito.runners.MockitoJUnitRunner;
 import org.springframework.amqp.core.MessageProperties;
+import org.springframework.amqp.support.converter.JsonMessageConverterTests.Foo;
 
 /**
  * @author James Carr
- * 
+ * @author Gary Russell
+ *
  */
 @RunWith(MockitoJUnitRunner.class)
 public class DefaultClassMapperTest {
 	@Spy
 	DefaultClassMapper classMapper = new DefaultClassMapper();
+
 	private final MessageProperties props = new MessageProperties();
 
 	@Test
@@ -115,6 +119,17 @@ public class DefaultClassMapperTest {
 		assertThat(className, equalTo("Hashtable"));
 	}
 
+	@SuppressWarnings("unchecked")
+	@Test
+	public void shouldUseDefaultType() {
+		props.getHeaders().clear();
+		classMapper.setDefaultType(Foo.class);
+		Class<Foo> clazz = (Class<Foo>) classMapper.toClass(props);
+
+		assertSame(Foo.class, clazz);
+		classMapper.setDefaultType(null);
+	}
+
 	private Map<String, Class<?>> map(String string, Class<?> class1) {
 		Map<String, Class<?>> map = new HashMap<String, Class<?>>();
 		map.put(string, class1);

spring-amqp/src/test/java/org/springframework/amqp/support/converter/JsonMessageConverterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2010 the original author or authors. Licensed under the Apache License, Version 2.0 (the "License");
+ * Copyright 2002-2012 the original author or authors. Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License. You may obtain a copy of the License at
  * http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
@@ -10,6 +10,7 @@
 package org.springframework.amqp.support.converter;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
 
 import java.math.BigDecimal;
 import java.util.Hashtable;
@@ -18,19 +19,29 @@ import org.codehaus.jackson.map.ObjectMapper;
 import org.codehaus.jackson.map.ser.BeanSerializerFactory;
 import org.junit.Before;
 import org.junit.Test;
+import org.junit.runner.RunWith;
 import org.springframework.amqp.core.Message;
 import org.springframework.amqp.core.MessageProperties;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 
 /**
  * @author Mark Pollack
  * @author Dave Syer
  * @author Sam Nelson
+ * @author Gary Russell
  */
+@ContextConfiguration
+@RunWith(SpringJUnit4ClassRunner.class)
 public class JsonMessageConverterTests {
 
 	private JsonMessageConverter converter;
 	private SimpleTrade trade;
 
+	@Autowired
+	private JsonMessageConverter jsonConverterWithDefaultType;
+
 	@Before
 	public void before(){
 		converter = new JsonMessageConverter();
@@ -43,7 +54,7 @@ public class JsonMessageConverterTests {
 		trade.setRequestId("R123");
 		trade.setTicker("VMW");
 		trade.setUserName("Joe Trader");
-		
+
 	}
    @Test
    public void simpleTrade() {
@@ -58,7 +69,7 @@ public class JsonMessageConverterTests {
       ObjectMapper mapper = new ObjectMapper();
       mapper.setSerializerFactory(BeanSerializerFactory.instance);
       converter.setJsonObjectMapper(mapper);
-      
+
       Message message = converter.toMessage(trade, new MessageProperties());
 
       SimpleTrade marshalledTrade = (SimpleTrade) converter.fromMessage(message);
@@ -82,25 +93,49 @@ public class JsonMessageConverterTests {
       Hashtable<String, String> hashtable = new Hashtable<String, String>();
       hashtable.put("TICKER", "VMW");
       hashtable.put("PRICE", "103.2");
-      
+
       Message message = converter.toMessage(hashtable, new MessageProperties());
       Hashtable<String, String> marhsalledHashtable = (Hashtable<String, String>) converter.fromMessage(message);
-      
+
       assertEquals("VMW", marhsalledHashtable.get("TICKER"));
       assertEquals("103.2", marhsalledHashtable.get("PRICE"));
    }
-   
+
    @Test
    public void shouldUseClassMapperWhenProvided() {
       Message message = converter.toMessage(trade, new MessageProperties());
-      
+
       converter.setClassMapper(new DefaultClassMapper());
       converter.setJavaTypeMapper(null);
-      
+
       SimpleTrade marshalledTrade = (SimpleTrade) converter.fromMessage(message);
       assertEquals(trade, marshalledTrade);
    }
 
+   @Test
+   public void testDefaultType() {
+	   byte[] bytes = "{\"name\" : \"foo\" }".getBytes();
+	   MessageProperties messageProperties = new MessageProperties();
+	   messageProperties.setContentType("application/json");
+	   Message message = new Message(bytes, messageProperties);
+	   JsonMessageConverter converter = new JsonMessageConverter();
+	   DefaultClassMapper classMapper = new DefaultClassMapper();
+	   classMapper.setDefaultType(Foo.class);
+	   converter.setClassMapper(classMapper);
+	   Object foo = converter.fromMessage(message);
+	   assertTrue(foo instanceof Foo);
+   }
+
+   @Test
+   public void testDefaultTypeConfig() {
+	   byte[] bytes = "{\"name\" : \"foo\" }".getBytes();
+	   MessageProperties messageProperties = new MessageProperties();
+	   messageProperties.setContentType("application/json");
+	   Message message = new Message(bytes, messageProperties);
+	   Object foo = jsonConverterWithDefaultType.fromMessage(message);
+	   assertTrue(foo instanceof Foo);
+   }
+
    public static class Foo {
       private String name = "foo";
 

spring-amqp/src/test/resources/org/springframework/amqp/support/converter/JsonMessageConverterTests-context.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans xmlns="http://www.springframework.org/schema/beans"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
+
+	<bean id="jsonConverterWithDefaultType" class="org.springframework.amqp.support.converter.JsonMessageConverter">
+		<property name="classMapper">
+			<bean class="org.springframework.amqp.support.converter.DefaultClassMapper">
+				<property name="defaultType"
+					value="org.springframework.amqp.support.converter.JsonMessageConverterTests$Foo" />
+			</bean>
+		</property>
+	</bean>
+
+</beans>

src/reference/docbook/amqp.xml

@@ -742,6 +742,22 @@ Object receiveAndConvert(String queueName) throws AmqpException;]]></programlist
         </bean>
     </property>
 </bean>]]></programlisting>
+
+      <para>As shown above, the <classname>JsonMessageConverter</classname> uses a
+      <classname>DefaultClassMapper</classname> by default. Type information is
+      added to (and retrieved from) the <classname>MessageProperties</classname>.
+      If an inbound message does not contain type information in the
+      <classname>MessageProperties</classname>, but you know the expected type,
+      you can configure a static type using the <code>defaultType</code> property</para>
+
+      <programlisting language="xml"><![CDATA[<bean id="jsonConverterWithDefaultType" class="org.springframework.amqp.support.converter.JsonMessageConverter">
+    <property name="classMapper">
+        <bean class="org.springframework.amqp.support.converter.DefaultClassMapper">
+            <property name="defaultType"
+                value="foo.PurchaseOrder" />
+        </bean>
+    </property>
+</bean>]]></programlisting>
     </sect2>
 
     <sect2>