Chapter 52. JacksonXML
Chapter 52. JacksonXML Jackson XML is a Data Format which uses the Jackson library with the XMLMapper extension to unmarshal an XML payload into Java objects or to marshal Java objects into an XML payload. NOTE: If you are familiar with Jackson, this XML data format behaves in the same way as its JSON counterpart, and thus can be used with classes annotated for JSON serialization/deserialization. This extension also mimics JAXB's "Code first" approach . This data format relies on Woodstox (especially for features like pretty printing), a fast and efficient XML processor. from("activemq:My.Queue"). unmarshal().jacksonxml(). to("mqseries:Another.Queue"); 52.1. Dependencies When using jacksonxml with Red Hat build of Camel Spring Boot make sure to use the following Maven dependency to have support for auto configuration: <dependency> <groupId>org.apache.camel.springboot</groupId> <artifactId>camel-jacksonxml-starter</artifactId> </dependency> 52.2. JacksonXML Options The JacksonXML dataformat supports 15 options, which are listed below. Name Default Java Type Description xmlMapper String Lookup and use the existing XmlMapper with the given id. prettyPrint false Boolean To enable pretty printing output nicely formatted. Is by default false. unmarshalType String Class name of the java type to use when unmarshalling. jsonView String When marshalling a POJO to JSON you might want to exclude certain fields from the JSON output. With Jackson you can use JSON views to accomplish this. This option is to refer to the class which has JsonView annotations. include String If you want to marshal a pojo to JSON, and the pojo has some fields with null values. And you want to skip these null values, you can set this option to NON_NULL. allowJmsType Boolean Used for JMS users to allow the JMSType header from the JMS spec to specify a FQN classname to use to unmarshal to. collectionType String Refers to a custom collection type to lookup in the registry to use. This option should rarely be used, but allows to use different collection types than java.util.Collection based as default. useList Boolean To unmarshal to a List of Map or a List of Pojo. enableJaxbAnnotationModule Boolean Whether to enable the JAXB annotations module when using jackson. When enabled then JAXB annotations can be used by Jackson. moduleClassNames String To use custom Jackson modules com.fasterxml.jackson.databind.Module specified as a String with FQN class names. Multiple classes can be separated by comma. moduleRefs String To use custom Jackson modules referred from the Camel registry. Multiple modules can be separated by comma. enableFeatures String Set of features to enable on the Jackson com.fasterxml.jackson.databind.ObjectMapper. The features should be a name that matches a enum from com.fasterxml.jackson.databind.SerializationFeature, com.fasterxml.jackson.databind.DeserializationFeature, or com.fasterxml.jackson.databind.MapperFeature Multiple features can be separated by comma. disableFeatures String Set of features to disable on the Jackson com.fasterxml.jackson.databind.ObjectMapper. The features should be a name that matches a enum from com.fasterxml.jackson.databind.SerializationFeature, com.fasterxml.jackson.databind.DeserializationFeature, or com.fasterxml.jackson.databind.MapperFeature Multiple features can be separated by comma. allowUnmarshallType Boolean If enabled then Jackson is allowed to attempt to use the CamelJacksonUnmarshalType header during the unmarshalling. This should only be enabled when desired to be used. contentTypeHeader Boolean Whether the data format should set the Content-Type header with the type from the data format. For example application/xml for data formats marshalling to XML, or application/json for data formats marshalling to JSON. 52.2.1. Using Jackson XML in Spring DSL When using Data Format in Spring DSL you need to declare the data formats first. This is done in the DataFormats XML tag. <dataFormats> <!-- here we define a Xml data format with the id jack and that it should use the TestPojo as the class type when doing unmarshal. The unmarshalType is optional, if not provided Camel will use a Map as the type --> <jacksonxml id="jack" unmarshalType="org.apache.camel.component.jacksonxml.TestPojo"/> </dataFormats> And then you can refer to this id in the route: <route> <from uri="direct:back"/> <unmarshal><custom ref="jack"/></unmarshal> <to uri="mock:reverse"/> </route> 52.2.2. Excluding POJO fields from marshalling When marshalling a POJO to XML you might want to exclude certain fields from the XML output. With Jackson you can use JSON views to accomplish this. First create one or more marker classes. Use the marker classes with the @JsonView annotation to include/exclude certain fields. The annotation also works on getters. Finally use the Camel JacksonXMLDataFormat to marshall the above POJO to XML. Note that the weight field is missing in the resulting XML: <pojo age="30" weight="70"/> 52.3. Include/Exclude fields using the jsonView attribute with `JacksonXML`DataFormat As an example of using this attribute you can instead of: JacksonXMLDataFormat ageViewFormat = new JacksonXMLDataFormat(TestPojoView.class, Views.Age.class); from("direct:inPojoAgeView"). marshal(ageViewFormat); Directly specify your JSON view inside the Java DSL as: from("direct:inPojoAgeView"). marshal().jacksonxml(TestPojoView.class, Views.Age.class); And the same in XML DSL: <from uri="direct:inPojoAgeView"/> <marshal> <jacksonxml unmarshalType="org.apache.camel.component.jacksonxml.TestPojoView" jsonView="org.apache.camel.component.jacksonxml.ViewsUSDAge"/> </marshal> 52.4. Setting serialization include option If you want to marshal a pojo to XML, and the pojo has some fields with null values. And you want to skip these null values, then you need to set either an annotation on the pojo, @JsonInclude(Include.NON_NULL) public class MyPojo { ... } But this requires you to include that annotation in your pojo source code. You can also configure the Camel JacksonXMLDataFormat to set the include option, as shown below: JacksonXMLDataFormat format = new JacksonXMLDataFormat(); format.setInclude("NON_NULL"); Or from XML DSL you configure this as <dataFormats> <jacksonxml id="jacksonxml" include="NON_NULL"/> </dataFormats> 52.5. Unmarshalling from XML to POJO with dynamic class name If you use jackson to unmarshal XML to POJO, then you can now specify a header in the message that indicate which class name to unmarshal to. The header has key CamelJacksonUnmarshalType if that header is present in the message, then Jackson will use that as FQN for the POJO class to unmarshal the XML payload as. JacksonDataFormat format = new JacksonDataFormat(); format.setAllowJmsType(true); Or from XML DSL you configure this as <dataFormats> <jacksonxml id="jacksonxml" allowJmsType="true"/> </dataFormats> 52.6. Unmarshalling from XML to List<Map> or List<pojo> If you are using Jackson to unmarshal XML to a list of map/pojo, you can now specify this by setting useList="true" or use the org.apache.camel.component.jacksonxml.ListJacksonXMLDataFormat . For example with Java you can do as shown below: JacksonXMLDataFormat format = new ListJacksonXMLDataFormat(); // or JacksonXMLDataFormat format = new JacksonXMLDataFormat(); format.useList(); // and you can specify the pojo class type also format.setUnmarshalType(MyPojo.class); And if you use XML DSL then you configure to use list using useList attribute as shown below: <dataFormats> <jacksonxml id="jack" useList="true"/> </dataFormats> And you can specify the pojo type also <dataFormats> <jacksonxml id="jack" useList="true" unmarshalType="com.foo.MyPojo"/> </dataFormats> 52.7. Using custom Jackson modules You can use custom Jackson modules by specifying the class names of those using the moduleClassNames option as shown below. <dataFormats> <jacksonxml id="jack" useList="true" unmarshalType="com.foo.MyPojo" moduleClassNames="com.foo.MyModule,com.foo.MyOtherModule"/> </dataFormats> When using moduleClassNames then the custom jackson modules are not configured, by created using default constructor and used as-is. If a custom module needs any custom configuration, then an instance of the module can be created and configured, and then use modulesRefs to refer to the module as shown below: <bean id="myJacksonModule" class="com.foo.MyModule"> ... // configure the module as you want </bean> <dataFormats> <jacksonxml id="jacksonxml" useList="true" unmarshalType="com.foo.MyPojo" moduleRefs="myJacksonModule"/> </dataFormats> 52.8. Enabling or disable features using Jackson Jackson has a number of features you can enable or disable, which its ObjectMapper uses. For example to disable failing on unknown properties when marshalling, you can configure this using the disableFeatures: <dataFormats> <jacksonxml id="jacksonxml" unmarshalType="com.foo.MyPojo" disableFeatures="FAIL_ON_UNKNOWN_PROPERTIES"/> </dataFormats> You can disable multiple features by separating the values using comma. The values for the features must be the name of the enums from Jackson from the following enum classes com.fasterxml.jackson.databind.SerializationFeature com.fasterxml.jackson.databind.DeserializationFeature com.fasterxml.jackson.databind.MapperFeature To enable a feature use the enableFeatures options instead. From Java code you can use the type safe methods from camel-jackson module: JacksonDataFormat df = new JacksonDataFormat(MyPojo.class); df.disableFeature(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES); df.disableFeature(DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES); 52.9. Converting Maps to POJO using Jackson Jackson ObjectMapper can be used to convert maps to POJO objects. Jackson component comes with the data converter that can be used to convert java.util.Map instance to non-String, non-primitive and non-Number objects. Map<String, Object> invoiceData = new HashMap<String, Object>(); invoiceData.put("netValue", 500); producerTemplate.sendBody("direct:mapToInvoice", invoiceData); ... // Later in the processor Invoice invoice = exchange.getIn().getBody(Invoice.class); If there is a single ObjectMapper instance available in the Camel registry, it will used by the converter to perform the conversion. Otherwise the default mapper will be used. 52.10. Formatted XML marshalling (pretty-printing) Using the prettyPrint option one can output a well formatted XML while marshalling: <dataFormats> <jacksonxml id="jack" prettyPrint="true"/> </dataFormats> And in Java DSL: from("direct:inPretty").marshal().jacksonxml(true); Please note that there are 5 different overloaded jacksonxml() DSL methods which support the prettyPrint option in combination with other settings for unmarshalType , jsonView etc. 52.11. Spring Boot Auto-Configuration The component supports 16 options, which are listed below. Name Description Default Type camel.dataformat.jacksonxml.allow-jms-type Used for JMS users to allow the JMSType header from the JMS spec to specify a FQN classname to use to unmarshal to. false Boolean camel.dataformat.jacksonxml.allow-unmarshall-type If enabled then Jackson is allowed to attempt to use the CamelJacksonUnmarshalType header during the unmarshalling. This should only be enabled when desired to be used. false Boolean camel.dataformat.jacksonxml.collection-type Refers to a custom collection type to lookup in the registry to use. This option should rarely be used, but allows to use different collection types than java.util.Collection based as default. String camel.dataformat.jacksonxml.content-type-header Whether the data format should set the Content-Type header with the type from the data format. For example application/xml for data formats marshalling to XML, or application/json for data formats marshalling to JSON. true Boolean camel.dataformat.jacksonxml.disable-features Set of features to disable on the Jackson com.fasterxml.jackson.databind.ObjectMapper. The features should be a name that matches a enum from com.fasterxml.jackson.databind.SerializationFeature, com.fasterxml.jackson.databind.DeserializationFeature, or com.fasterxml.jackson.databind.MapperFeature Multiple features can be separated by comma. String camel.dataformat.jacksonxml.enable-features Set of features to enable on the Jackson com.fasterxml.jackson.databind.ObjectMapper. The features should be a name that matches a enum from com.fasterxml.jackson.databind.SerializationFeature, com.fasterxml.jackson.databind.DeserializationFeature, or com.fasterxml.jackson.databind.MapperFeature Multiple features can be separated by comma. String camel.dataformat.jacksonxml.enable-jaxb-annotation-module Whether to enable the JAXB annotations module when using jackson. When enabled then JAXB annotations can be used by Jackson. false Boolean camel.dataformat.jacksonxml.enabled Whether to enable auto configuration of the jacksonxml data format. This is enabled by default. Boolean camel.dataformat.jacksonxml.include If you want to marshal a pojo to JSON, and the pojo has some fields with null values. And you want to skip these null values, you can set this option to NON_NULL. String camel.dataformat.jacksonxml.json-view When marshalling a POJO to JSON you might want to exclude certain fields from the JSON output. With Jackson you can use JSON views to accomplish this. This option is to refer to the class which has JsonView annotations. String camel.dataformat.jacksonxml.module-class-names To use custom Jackson modules com.fasterxml.jackson.databind.Module specified as a String with FQN class names. Multiple classes can be separated by comma. String camel.dataformat.jacksonxml.module-refs To use custom Jackson modules referred from the Camel registry. Multiple modules can be separated by comma. String camel.dataformat.jacksonxml.pretty-print To enable pretty printing output nicely formatted. Is by default false. false Boolean camel.dataformat.jacksonxml.unmarshal-type Class name of the java type to use when unmarshalling. String camel.dataformat.jacksonxml.use-list To unmarshal to a List of Map or a List of Pojo. false Boolean camel.dataformat.jacksonxml.xml-mapper Lookup and use the existing XmlMapper with the given id. String
from("activemq:My.Queue"). unmarshal().jacksonxml(). to("mqseries:Another.Queue"); <dependency> <groupId>org.apache.camel.springboot</groupId> <artifactId>camel-jacksonxml-starter</artifactId> </dependency> <dataFormats> <!-- here we define a Xml data format with the id jack and that it should use the TestPojo as the class type when doing unmarshal. The unmarshalType is optional, if not provided Camel will use a Map as the type --> <jacksonxml id="jack" unmarshalType="org.apache.camel.component.jacksonxml.TestPojo"/> </dataFormats> <route> <from uri="direct:back"/> <unmarshal><custom ref="jack"/></unmarshal> <to uri="mock:reverse"/> </route> <pojo age="30" weight="70"/> JacksonXMLDataFormat ageViewFormat = new JacksonXMLDataFormat(TestPojoView.class, Views.Age.class); from("direct:inPojoAgeView"). marshal(ageViewFormat); from("direct:inPojoAgeView"). marshal().jacksonxml(TestPojoView.class, Views.Age.class); <from uri="direct:inPojoAgeView"/> <marshal> <jacksonxml unmarshalType="org.apache.camel.component.jacksonxml.TestPojoView" jsonView="org.apache.camel.component.jacksonxml.ViewsUSDAge"/> </marshal> @JsonInclude(Include.NON_NULL) public class MyPojo { } JacksonXMLDataFormat format = new JacksonXMLDataFormat(); format.setInclude("NON_NULL"); <dataFormats> <jacksonxml id="jacksonxml" include="NON_NULL"/> </dataFormats> For JMS end users there is the JMSType header from the JMS spec that indicates that also. To enable support for JMSType you would need to turn that on, on the jackson data format as shown: JacksonDataFormat format = new JacksonDataFormat(); format.setAllowJmsType(true); <dataFormats> <jacksonxml id="jacksonxml" allowJmsType="true"/> </dataFormats> JacksonXMLDataFormat format = new ListJacksonXMLDataFormat(); // or JacksonXMLDataFormat format = new JacksonXMLDataFormat(); format.useList(); // and you can specify the pojo class type also format.setUnmarshalType(MyPojo.class); <dataFormats> <jacksonxml id="jack" useList="true"/> </dataFormats> <dataFormats> <jacksonxml id="jack" useList="true" unmarshalType="com.foo.MyPojo"/> </dataFormats> <dataFormats> <jacksonxml id="jack" useList="true" unmarshalType="com.foo.MyPojo" moduleClassNames="com.foo.MyModule,com.foo.MyOtherModule"/> </dataFormats> <bean id="myJacksonModule" class="com.foo.MyModule"> ... // configure the module as you want </bean> <dataFormats> <jacksonxml id="jacksonxml" useList="true" unmarshalType="com.foo.MyPojo" moduleRefs="myJacksonModule"/> </dataFormats> Multiple modules can be specified separated by comma, such as moduleRefs="myJacksonModule,myOtherModule" <dataFormats> <jacksonxml id="jacksonxml" unmarshalType="com.foo.MyPojo" disableFeatures="FAIL_ON_UNKNOWN_PROPERTIES"/> </dataFormats> JacksonDataFormat df = new JacksonDataFormat(MyPojo.class); df.disableFeature(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES); df.disableFeature(DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES); Map<String, Object> invoiceData = new HashMap<String, Object>(); invoiceData.put("netValue", 500); producerTemplate.sendBody("direct:mapToInvoice", invoiceData); // Later in the processor Invoice invoice = exchange.getIn().getBody(Invoice.class); <dataFormats> <jacksonxml id="jack" prettyPrint="true"/> </dataFormats> from("direct:inPretty").marshal().jacksonxml(true);