INT-2809: Add/Extract JSON JavaType Headers
* Add `AmqpHeaders` headers * Add `JavaType` headers mapping to `DefaultAmqpHeaderMapper` * Add ability to Json Transformers to add/extract `JavaType` headers * Make `JsonToObjectTransformer#targetClass` as non-required and do fallback to extract type from `JavaType` headers * Add `JavaType` extraction in the `JsonObjectMapper` implementors JIRA: https://jira.springsource.org/browse/INT-2809 INT-2809: Polishing and refactoring * Introduce `JsonHeaders`, `AbstractJacksonJsonObjectMapper` * Move `TestPerson` and `TestAddress` to package level * Now `JsonToObjectTransformer` supports not only `String` payload * Remove json headers after transformation in the `JsonToObjectTransformer` INT-2809 Minor Polishing INT-2809 Docs and What's New
This commit is contained in:
Artem Bilan
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Gary Russell
Gary Russell
parent
c389604c2e
commit
4dd95c41ea
@@ -206,7 +206,7 @@ public class Kid {
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a BeanCreationException will be thrown.
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</note>
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<para>
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<emphasis>JSON Transformers</emphasis>
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<emphasis role="bold">JSON Transformers</emphasis>
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</para>
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<para>
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<emphasis>Object to JSON</emphasis> and <emphasis>JSON to Object</emphasis> transformers are provided.
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@@ -279,7 +279,7 @@ public class Foo {
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</para>
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<important>
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<para>
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Beginning with version 2.2, the <code>object-to-json-transformer</code> sets the <emphasis>content-type</emphasis>
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Beginning with <emphasis>version 2.2</emphasis>, the <code>object-to-json-transformer</code> sets the <emphasis>content-type</emphasis>
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header to <code>application/json</code>, by default, if the input message does not already have that header
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present.
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</para>
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@@ -290,66 +290,50 @@ public class Foo {
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attribute to an empty string (<code>""</code>). This will result in a message with no <code>content-type</code>
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header, unless such a header was present on the input message.
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</para>
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<para>
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The behavior of adding the default header has a side affect - causing applications with the following
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sequence to fail:
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</para>
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<para>
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<code>->object-to-json-transformer->amqp-outbound-adapter----></code>
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</para>
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<para>
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<code>---->amqp-inbound-adapter->json-to-object-transformer-></code>
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</para>
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<para>
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This is because the default <classname>SimpleMessageConverter</classname> used by the inbound adapter doesn't
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recognize this content type and the adapter emits a message with a <code>byte[]</code> payload instead of
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<code>String</code>, which was the case with earlier versions.
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</para>
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<para>
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If you are using this pattern, there are a number of ways to configure the environment so that JSON
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conversion will be performed correctly.
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</para>
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<para>
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One solution is to set the content type to a text type, so the inbound converter will convert the JSON to
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String. This solution requires a change to just the outbound application.
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</para>
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<para>
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<programlisting language="xml"><![CDATA[<object-to-json-transformer ... content-type="text/x-json"/>]]></programlisting>
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</para>
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<para>
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The second solution is to eliminate the json transformers altogether and use an
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<classname>org.springframework.amqp.support.converter.JsonMessageConverter</classname> on both the
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outbound and inbound adapters. This configures the adapters to perform the JSON conversion and
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the transformers are not necessary. The converter on the outbound adapter adds
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type information to the message properties; the inbound converter uses this type information for the conversion.
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The converter is provided to the adapters using the <emphasis>message-converter</emphasis> attribute.
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This solution requires a change to both the inbound and outbound applications.
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</para>
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<para>
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The third solution is to eliminate the <emphasis>json-to-object-transformer</emphasis> in just
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the inbound application and use an
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<classname>org.springframework.amqp.support.converter.JsonMessageConverter</classname> on the
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inbound adapter. The converter
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is provided to the adapter using the <emphasis>message-converter</emphasis> attribute.
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However, because there will be no type information in the message properties,
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this also requires adding the <emphasis>defaultType</emphasis> to the converter, using the
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same type as currently configured on the <emphasis>json-to-object-transformer</emphasis>.
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This solution requires a change to just the inbound application. The configuration below shows
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how to configure the message converter; it requires <code>spring-amqp</code> 1.1.3 or
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above.
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</para>
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<programlisting language="xml"><![CDATA[<bean id="jsonConverterWithPOType"
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class="org.springframework.amqp.support.converter.JsonMessageConverter">
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<property name="classMapper">
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<bean class="org.springframework.amqp.support.converter.DefaultClassMapper">
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<property name="defaultType"
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value="foo.PurchaseOrder" />
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</bean>
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</property>
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</bean>
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<int-amqp:inbound-channel-adapter ... message-converter="jsonConverterWithPOType" ... />]]></programlisting>
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</important>
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<para>
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Beginning with <emphasis>version 3.0</emphasis>, the <classname>ObjectToJsonTransformer</classname> adds headers,
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reflecting the source type, to the message. Similarly, the <classname>JsonToObjectTransformer</classname> can
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use those type headers when converting the JSON to an object. These headers are mapped in the AMQP adapters so that
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they are entirely compatible with the Spring-AMQP
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<ulink url="http://docs.spring.io/spring-amqp/api/">JsonMessageConverter</ulink>.
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</para>
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<para>
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This enables the following flows to work without any special configuration...
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</para>
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<para>
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<code>...->amqp-outbound-adapter----></code>
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</para>
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<para>
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<code>---->amqp-inbound-adapter->json-to-object-transformer->...</code>
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</para>
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<para>
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Where the outbound adapter is configured with a <classname>JsonMessageConverter</classname> and the
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inbound adapter uses the default <classname>SimpleMessageConverter</classname>.
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</para>
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<para>
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<code>...->object-to-json-transformer->amqp-outbound-adapter----></code>
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</para>
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<para>
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<code>---->amqp-inbound-adapter->...</code>
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</para>
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<para>
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Where the outbound adapter is configured with a <classname>SimpleMessageConverter</classname> and the
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inbound adapter uses the default <classname>JsonMessageConverter</classname>.
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</para>
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<para>
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<code>...->object-to-json-transformer->amqp-outbound-adapter----></code>
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</para>
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<para>
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<code>---->amqp-inbound-adapter->json-to-object-transformer-></code>
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</para>
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<para>
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Where both adapters are configured with a <classname>SimpleMessageConverter</classname>.
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</para>
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<note>
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When using the headers to determine the type, you should <emphasis role="bold">not</emphasis> provide
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a <code>class</code> attribute, because it takes precedence over the headers.
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</note>
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<para>
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In addition to JSON Transformers, Spring Integration provides a built-in <emphasis>#jsonPath</emphasis>
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SpEL function for use in expressions. For more information see <xref linkend="spel"/>.
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@@ -325,10 +325,20 @@
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<section id="3.0-json-transformers">
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<title>Jackson Support (JSON)</title>
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<para>
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A new abstraction for JSON conversion has been introduced. Implementations for Jackson 1.x
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and Jackson 2 are currently provided, with the version being determined by presence on
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the classpath. Previously, only Jackson 1.x was supported. For more information,
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see 'JSON Transformers' in <xref linkend="transformer"/>.
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<itemizedlist>
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<listitem>
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A new abstraction for JSON conversion has been introduced. Implementations for Jackson 1.x
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and Jackson 2 are currently provided, with the version being determined by presence on
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the classpath. Previously, only Jackson 1.x was supported.
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</listitem>
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<listitem>
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The <classname>ObjectToJsonTransformer</classname> and <classname>JsonToObjectTransformer</classname>
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now emit/consume headers containing type information.
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</listitem>
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</itemizedlist>
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</para>
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<para>
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For more information, see 'JSON Transformers' in <xref linkend="transformer"/>.
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</para>
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</section>
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<section id="3.0-http-endpointss">
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