Introduction Marshaller and Unmarshaller
21. Marshalling XML using OX Mappers
21.1 Introduction
In this chapter, we will describe Spring’s ObjectXML Mapping support. ObjectXML Mapping, or OX mapping for short, is the act of converting an XML document to and from an object. This conversion process is also known as XML Marshalling, or XML Serialization. This chapter uses these terms interchangeably. Within the field of OX mapping, a marshaller is responsible for serializing an object graph to XML. In similar fashion, an unmarshaller deserializes the XML to an object graph. This XML can take the form of a DOM document, an input or output stream, or a SAX handler. Some of the benefits of using Spring for your OX mapping needs are: Ease of configuration Spring’s bean factory makes it easy to configure marshallers, without needing to construct JAXB context, JiBX binding factories, etc. The marshallers can be configured as any other bean in your application context. Additionally, XML Schema-based configuration is available for a number of marshallers, making the configuration even simpler. Consistent Interfaces Spring’s OX mapping operates through two global interfaces: the Marshaller and Unmarshaller interface. These abstractions allow you to switch OX mapping frameworks with relative ease, with little or no changes required on the classes that do the marshalling. This approach has the additional benefit of making it possible to do XML marshalling with a mix-and-match approach e.g. some marshalling performed using JAXB, other using XMLBeans in a non-intrusive fashion, leveraging the strength of each technology. Consistent Exception Hierarchy Spring provides a conversion from exceptions from the underlying OX mapping tool to its own exception hierarchy with the XmlMappingException as the root exception. As can be expected, these runtime exceptions wrap the original exception so no information is lost.21.2 Marshaller and Unmarshaller
As stated in the introduction, a marshaller serializes an object to XML, and an unmarshaller deserializes XML stream to an object. In this section, we will describe the two Spring interfaces used for this purpose. Marshaller Spring abstracts all marshalling operations behind the org.springframework.oxm.Marshaller interface, the main method of which is shown below. public interface Marshaller { Marshal the object graph with the given root into the provided Result. void marshalObject graph, Result result throws XmlMappingException, IOException; } 4.3.9.RELEASE Spring Framework 468 The Marshaller interface has one main method, which marshals the given object to a given javax.xml.transform.Result . Result is a tagging interface that basically represents an XML output abstraction: concrete implementations wrap various XML representations, as indicated in the table below. Result implementation Wraps XML representation DOMResult org.w3c.dom.Node SAXResult org.xml.sax.ContentHandler StreamResult java.io.File , java.io.OutputStream , or java.io.Writer Note Although the marshal method accepts a plain object as its first parameter, most Marshaller implementations cannot handle arbitrary objects. Instead, an object class must be mapped in a mapping file, marked with an annotation, registered with the marshaller, or have a common base class. Refer to the further sections in this chapter to determine how your OX technology of choice manages this. Unmarshaller Similar to the Marshaller , there is the org.springframework.oxm.Unmarshaller interface. public interface Unmarshaller { Unmarshal the given provided Source into an object graph. Object unmarshalSource source throws XmlMappingException, IOException; } This interface also has one method, which reads from the given javax.xml.transform.Source an XML input abstraction, and returns the object read. As with Result, Source is a tagging interface that has three concrete implementations. Each wraps a different XML representation, as indicated in the table below. Source implementation Wraps XML representation DOMSource org.w3c.dom.Node SAXSource org.xml.sax.InputSource , and org.xml.sax.XMLReader StreamSource java.io.File , java.io.InputStream , or java.io.Reader Even though there are two separate marshalling interfaces Marshaller and Unmarshaller , all implementations found in Spring-WS implement both in one class. This means that you can wire up one marshaller class and refer to it both as a marshaller and an unmarshaller in your applicationContext.xml . 4.3.9.RELEASE Spring Framework 469 XmlMappingException Spring converts exceptions from the underlying OX mapping tool to its own exception hierarchy with the XmlMappingException as the root exception. As can be expected, these runtime exceptions wrap the original exception so no information will be lost. Additionally, the MarshallingFailureException and UnmarshallingFailureException provide a distinction between marshalling and unmarshalling operations, even though the underlying OX mapping tool does not do so. The OX Mapping exception hierarchy is shown in the following figure: OX Mapping exception hierarchy21.3 Using Marshaller and Unmarshaller
Parts
» Dependency Injection and Inversion of Control Framework Modules
» Usage scenarios Introduction to the Spring Framework
» Java EE 6 and 7 Groovy Bean Definition DSL
» Core Container Improvements General Web Improvements
» WebSocket, SockJS, and STOMP Messaging Testing Improvements
» JMS Improvements Caching Improvements
» Web Improvements New Features and Enhancements in Spring Framework 1
» WebSocket Messaging Improvements Testing Improvements
» Core Container Improvements New Features and Enhancements in Spring Framework 4.2
» Data Access Improvements JMS Improvements Web Improvements
» Core Container Improvements Data Access Improvements Caching Improvements
» JMS Improvements Web Improvements WebSocket Messaging Improvements Testing Improvements
» Introduction to the Spring IoC container and beans
» Container overview The IoC container
» Bean overview The IoC container
» Dependencies The IoC container
» y.Baz beans The IoC container
» driverClassName = username = The IoC container
» email = spouse-ref = The IoC container
» y.Bar bean y.Foo constructor-arg y.Foo c:bar-ref baz-ref = y.Foo c:_0-ref _1-ref =
» y.z.MyValueCalculator b.c.ReplacementComputeValue Bean scopes
» y.Foo property Customizing the nature of a bean
» Bean definition inheritance The IoC container
» Container Extension Points The IoC container
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» Using JSR 330 Standard Annotations
» Java-based container configuration The IoC container
» Environment abstraction The IoC container
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» The BeanFactory The IoC container
» Introduction The Resource interface
» Built-in Resource implementations Resources
» The ResourceLoaderAware interface Resources
» Resources as dependencies Application contexts and Resource paths
» Introduction Validation, Data Binding, and Type Conversion
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» Spring Type Conversion Validation, Data Binding, and Type Conversion
» Spring Field Formatting Validation, Data Binding, and Type Conversion
» Configuring a global date time format
» Spring Validation Validation, Data Binding, and Type Conversion
» Introduction Feature Overview Spring Expression Language SpEL
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» Language Reference Spring Expression Language SpEL
» 3e0 4 .getValueDouble. 4e0 2 .getValueDouble.
» Classes used in the examples
» Introduction Aspect Oriented Programming with Spring
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» y.service.DefaultFooService y.SimpleProfiler aop:config
» Choosing which AOP declaration style to use
» Mixing aspect types Proxying mechanisms
» Introduction Pointcut API in Spring
» Advisor API in Spring Using the ProxyFactoryBean to create AOP proxies
» Concise proxy definitions Spring AOP APIs
» Creating AOP proxies programmatically with the ProxyFactory Manipulating advised objects
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» Using TargetSources Spring AOP APIs
» Mock Objects Unit Testing support Classes
» Overview Goals of Integration Testing
» JDBC Testing Support Annotations
» Spring TestContext Framework Integration Testing
» loginAction-ref = username = userPreferences-ref = theme =
» PetClinic Example Integration Testing
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» y.service.DefaultFooService Transaction Management
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» y.SimpleProfiler Transaction Management
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» Application server-specific integration Transaction Management
» Introduction Consistent exception hierarchy
» Annotations used for configuring DAO or Repository classes
» Introduction to Spring Framework JDBC
» Using the JDBC core classes to control basic JDBC processing and error handling
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» Introduction to ORM with Spring
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» JDO Object Relational Mapping ORM Data Access
» Introduction Marshaller and Unmarshaller
» Using Marshaller and Unmarshaller
» XML Schema-based Configuration JAXB
» Castor Marshalling XML using OX Mappers
» XMLBeans JiBX Marshalling XML using OX Mappers
» XStream Marshalling XML using OX Mappers
» Introduction to Spring Web MVC framework
» The DispatcherServlet Web MVC framework
» Handler mappings Web MVC framework
» Resolving views Web MVC framework
» Using flash attributes Web MVC framework
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» y.RegistrationController HTTP caching support
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» simpleDateFormat = Web MVC framework
» Introduction Thymeleaf Groovy Markup Templates
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» Introduction Integrating with other web frameworks
» Common configuration Integrating with other web frameworks
» JavaServer Faces 1.2 Apache Struts 2.x
» Introduction Portlet MVC Framework
» The DispatcherPortlet Portlet MVC Framework
» The ViewRendererServlet Controllers Portlet MVC Framework
» Handler mappings Portlet MVC Framework
» Views and resolving them Multipart file upload support
» Handling exceptions Annotation-based controller configuration
» absolute-ordering absolute-ordering WebSocket API
» SockJS Fallback Options WebSocket Support
» STOMP Over WebSocket Messaging Architecture
» Introduction Controller method CORS configuration
» Global CORS configuration Advanced Customization
» Introduction Remoting and web services using Spring
» Using Hessian or Burlap to remotely call services via HTTP
» Exposing services using HTTP invokers
» Web services Remoting and web services using Spring
» JMS Remoting and web services using Spring
» Accessing RESTful services on the Client
» Introduction Accessing EJBs Enterprise JavaBeans EJB integration
» Introduction JMS Java Message Service
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» Sending a Message JMS Java Message Service
» Receiving a message JMS Java Message Service
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» Introduction Exporting your beans to JMX
» Controlling the management interface of your beans
» Controlling the ObjectNames for your beans
» Accessing MBeans via Proxies
» Introduction Configuring CCI JCA CCI
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» Modeling CCI access as operation objects
» Using the JavaMail MimeMessageHelper
» Introduction The Spring TaskExecutor abstraction
» The Spring TaskScheduler abstraction
» Annotation Support for Scheduling and Asynchronous Execution
» The task namespace Task Execution and Scheduling
» Introduction A first example
» y.DefaultBookingService property Defining beans that are backed by dynamic languages
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» Scenarios Dynamic language support
» Bits and bobs y.DefaultBookingService property
» Introduction Understanding the cache abstraction
» Declarative annotation-based caching Cache Abstraction
» JCache JSR-107 annotations Cache Abstraction
» Declarative XML-based caching y.service.DefaultBookService
» Configuring the cache storage name =
» Classic ORM usage Classic Spring Usage
» JMS Usage Classic Spring Usage
» Concise proxy definitions Classic Spring AOP Usage
» Using the autoproxy facility
» Using TargetSources Classic Spring AOP Usage
» Introduction XML Schema-based configuration
» Introduction Authoring the schema
» Coding a NamespaceHandler Extensible XML authoring
» BeanDefinitionParser Extensible XML authoring
» Registering the handler and the schema
» Using a custom extension in your Spring XML configuration Meatier examples
» Introduction The argument tag The bind tag
» The escapeBody tag The eval tag The hasBindErrors tag
» The htmlEscape tag The message tag
» The nestedPath tag The param tag The theme tag
» The transform tag The url tag
» Introduction The button tag The checkbox tag
» The checkboxes tag The errors tag
» The option tag The options tag
» The password tag The radiobutton tag
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