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EclipseLink 2.2.0, build 'v20110202-r8913' API Reference | ||||||||
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java.lang.Objectjavax.xml.bind.JAXBContext
public abstract class JAXBContext
The JAXBContext class provides the client's entry point to the JAXB API. It provides an abstraction for managing the XML/Java binding information necessary to implement the JAXB binding framework operations: unmarshal, marshal and validate.
A client application normally obtains new instances of this class using one of these two styles for newInstance methods, although there are other specialized forms of the method available:
JAXBContext.newInstance( "com.acme.foo:com.acme.bar" )
JAXBContext.newInstance( com.acme.foo.Foo.class )
newInstance(Class...)
for details.
SPEC REQUIREMENT: the provider must supply an implementation class containing the following method signatures:
public static JAXBContext createContext( String contextPath, ClassLoader classLoader, Mapproperties ) throws JAXBException public static JAXBContext createContext( Class[] classes, Map properties ) throws JAXBException
The following JAXB 1.0 requirement is only required for schema to java interface/implementation binding. It does not apply to JAXB annotated classes. JAXB Providers must generate a jaxb.properties file in each package containing schema derived classes. The property file must contain a property named javax.xml.bind.context.factory whose value is the name of the class that implements the createContext APIs.
The class supplied by the provider does not have to be assignable to javax.xml.bind.JAXBContext, it simply has to provide a class that implements the createContext APIs.
In addition, the provider must call the
DatatypeConverter.setDatatypeConverter
api prior to any client
invocations of the marshal and unmarshal methods. This is necessary to
configure the datatype converter that will be used during these operations.
The Unmarshaller
class provides the client application the ability
to convert XML data into a tree of Java content objects.
The unmarshal method allows for
any global XML element declared in the schema to be unmarshalled as
the root of an instance document.
Additionally, the unmarshal method allows for an unrecognized root element that
has an xsi:type attribute's value that references a type definition declared in
the schema to be unmarshalled as the root of an instance document.
The JAXBContext object
allows the merging of global elements and type definitions across a set of schemas (listed
in the contextPath). Since each schema in the schema set can belong
to distinct namespaces, the unification of schemas to an unmarshalling
context should be namespace independent. This means that a client
application is able to unmarshal XML documents that are instances of
any of the schemas listed in the contextPath. For example:
JAXBContext jc = JAXBContext.newInstance( "com.acme.foo:com.acme.bar" ); Unmarshaller u = jc.createUnmarshaller(); FooObject fooObj = (FooObject)u.unmarshal( new File( "foo.xml" ) ); // ok BarObject barObj = (BarObject)u.unmarshal( new File( "bar.xml" ) ); // ok BazObject bazObj = (BazObject)u.unmarshal( new File( "baz.xml" ) ); // error, "com.acme.baz" not in contextPath
The client application may also generate Java content trees explicitly rather than unmarshalling existing XML data. For all JAXB-annotated value classes, an application can create content using constructors. For schema-derived interface/implementation classes and for the creation of elements that are not bound to a JAXB-annotated class, an application needs to have access and knowledge about each of the schema derived ObjectFactory classes that exist in each of java packages contained in the contextPath. For each schema derived java class, there is a static factory method that produces objects of that type. For example, assume that after compiling a schema, you have a package com.acme.foo that contains a schema derived interface named PurchaseOrder. In order to create objects of that type, the client application would use the factory method like this:
com.acme.foo.PurchaseOrder po = com.acme.foo.ObjectFactory.createPurchaseOrder();
Once the client application has an instance of the the schema derived object, it can use the mutator methods to set content on it.
For more information on the generated ObjectFactory classes, see Section 4.2 Java Package of the specification.
SPEC REQUIREMENT: the provider must generate a class in each package that contains all of the necessary object factory methods for that package named ObjectFactory as well as the static newInstance( javaContentInterface ) method
The Marshaller
class provides the client application the ability
to convert a Java content tree back into XML data. There is no difference
between marshalling a content tree that is created manually using the factory
methods and marshalling a content tree that is the result an unmarshal
operation. Clients can marshal a java content tree back to XML data
to a java.io.OutputStream or a java.io.Writer. The
marshalling process can alternatively produce SAX2 event streams to a
registered ContentHandler or produce a DOM Node object.
Client applications have control over the output encoding as well as
whether or not to marshal the XML data as a complete document or
as a fragment.
Here is a simple example that unmarshals an XML document and then marshals it back out:
JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" ); // unmarshal from foo.xml Unmarshaller u = jc.createUnmarshaller(); FooObject fooObj = (FooObject)u.unmarshal( new File( "foo.xml" ) ); // marshal to System.out Marshaller m = jc.createMarshaller(); m.marshal( fooObj, System.out );
Validation has been changed significantly since JAXB 1.0. The Validator
class has been deprecated and made optional. This means that you are advised
not to use this class and, in fact, it may not even be available depending on
your JAXB provider. JAXB 1.0 client applications that rely on Validator
will still work properly when deployed with the JAXB 1.0 runtime system.
In JAXB 2.0, the Unmarshaller
has included convenince methods that expose
the JAXP 1.3 javax.xml.validation
framework. Please refer to the
Unmarshaller.setSchema(javax.xml.validation.Schema)
API for more
information.
The following JAXB 1.0 restriction only applies to binding schema to interfaces/implementation classes. Since this binding does not require a common runtime system, a JAXB client application must not attempt to mix runtime objects (JAXBContext, Marshaller, etc. ) from different providers. This does not mean that the client application isn't portable, it simply means that a client has to use a runtime system provided by the same provider that was used to compile the schema.
When one of the newInstance methods is called, a JAXB implementation is discovered by the following steps.
newInstance(java.lang.String)
method, in the order they are specified,
jaxb.properties file is looked up in its package, by using the associated classloader —
this is the owner class loader
for a Class
argument, and for a package
the speified ClassLoader
.
If such a file is discovered, it is loaded
as a property file, and
the value of the JAXB_CONTEXT_FACTORY
key will be assumed to be the provider factory class.
This class is then loaded by the associated classloader discussed above.
This phase of the look up allows some packages to force the use of a certain JAXB implementation. (For example, perhaps the schema compiler has generated some vendor extension in the code.)
JAXB_CONTEXT_FACTORY
exists, then its value is assumed to be the provider
factory class. This phase of the look up enables per-JVM override of the JAXB implementation.
Once the provider factory class is discovered, its
public static JAXBContext createContext(String,ClassLoader,Map) method
(see newInstance(String, ClassLoader, Map)
for the parameter semantics.)
or public static JAXBContext createContet(Class[],Map) method
(see newInstance(Class[], Map)
for the parameter semantics) are invoked
to create a JAXBContext
.
Marshaller
,
Unmarshaller
,
S 7.4.1.1 "Package Annotations" in Java Language Specification, 3rd EditionField Summary | |
---|---|
static java.lang.String |
JAXB_CONTEXT_FACTORY
The name of the property that contains the name of the class capable of creating new JAXBContext objects. |
Constructor Summary | |
---|---|
protected |
JAXBContext()
|
Method Summary | ||
---|---|---|
Binder<org.w3c.dom.Node> |
createBinder()
Creates a Binder for W3C DOM. |
|
|
createBinder(java.lang.Class<T> domType)
Creates a Binder object that can be used for associative/in-place unmarshalling/marshalling. |
|
JAXBIntrospector |
createJAXBIntrospector()
Creates a JAXBIntrospector object that can be used to introspect JAXB objects. |
|
abstract Marshaller |
createMarshaller()
Create a Marshaller object that can be used to convert a java content tree into XML data. |
|
abstract Unmarshaller |
createUnmarshaller()
Create an Unmarshaller object that can be used to convert XML data into a java content tree. |
|
abstract Validator |
createValidator()
Deprecated. since JAXB2.0 |
|
void |
generateSchema(SchemaOutputResolver outputResolver)
Generates the schema documents for this context. |
|
static JAXBContext |
newInstance(java.lang.Class... classesToBeBound)
Obtain a new instance of a JAXBContext class. |
|
static JAXBContext |
newInstance(java.lang.Class[] classesToBeBound,
java.util.Map<java.lang.String,?> properties)
Obtain a new instance of a JAXBContext class. |
|
static JAXBContext |
newInstance(java.lang.String contextPath)
Obtain a new instance of a JAXBContext class. |
|
static JAXBContext |
newInstance(java.lang.String contextPath,
java.lang.ClassLoader classLoader)
Obtain a new instance of a JAXBContext class. |
|
static JAXBContext |
newInstance(java.lang.String contextPath,
java.lang.ClassLoader classLoader,
java.util.Map<java.lang.String,?> properties)
Obtain a new instance of a JAXBContext class. |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
---|
public static final java.lang.String JAXB_CONTEXT_FACTORY
Constructor Detail |
---|
protected JAXBContext()
Method Detail |
---|
public static JAXBContext newInstance(java.lang.String contextPath) throws JAXBException
Obtain a new instance of a JAXBContext class.
This is a convenience method to invoke the
newInstance(String,ClassLoader)
method with
the context class loader of the current thread.
JAXBException
- if an error was encountered while creating the
JAXBContext such as
public static JAXBContext newInstance(java.lang.String contextPath, java.lang.ClassLoader classLoader) throws JAXBException
Obtain a new instance of a JAXBContext class.
The client application must supply a context path which is a list of colon (':', \u003A) separated java package names that contain schema-derived classes and/or fully qualified JAXB-annotated classes. Schema-derived code is registered with the JAXBContext by the ObjectFactory.class generated per package. Alternatively than being listed in the context path, programmer annotated JAXB mapped classes can be listed in a jaxb.index resource file, format described below. Note that a java package can contain both schema-derived classes and user annotated JAXB classes. Additionally, the java package may contain JAXB package annotations that must be processed. (see JLS 3rd Edition, Section 7.4.1. "Package Annotations").
Every package listed on the contextPath must meet one or both of the following conditions otherwise a JAXBException will be thrown:
Format for jaxb.index
The file contains a newline-separated list of class names.
Space and tab characters, as well as blank
lines, are ignored. The comment character
is '#' (0x23); on each line all characters following the first comment
character are ignored. The file must be encoded in UTF-8. Classes that
are reachable, as defined in newInstance(Class...)
, from the
listed classes are also registered with JAXBContext.
Constraints on class name occuring in a jaxb.index file are:
To maintain compatibility with JAXB 1.0 schema to java
interface/implementation binding, enabled by schema customization
If there are any global XML element name collisions across the various packages listed on the contextPath, a JAXBException will be thrown.
Mixing generated interface/impl bindings from multiple JAXB Providers in the same context path may result in a JAXBException being thrown.
The steps involved in discovering the JAXB implementation is discussed in the class javadoc.
contextPath
- list of java package names that contain schema
derived class and/or java to schema (JAXB-annotated)
mapped classesclassLoader
- This class loader will be used to locate the implementation
classes.
JAXBException
- if an error was encountered while creating the
JAXBContext such as
public static JAXBContext newInstance(java.lang.String contextPath, java.lang.ClassLoader classLoader, java.util.Map<java.lang.String,?> properties) throws JAXBException
Obtain a new instance of a JAXBContext class.
This is mostly the same as newInstance(String, ClassLoader)
,
but this version allows you to pass in provider-specific properties to configure
the instanciation of JAXBContext
.
The interpretation of properties is up to implementations. Implementations should throw JAXBException if it finds properties that it doesn't understand.
contextPath
- list of java package names that contain schema derived classesclassLoader
- This class loader will be used to locate the implementation classes.properties
- provider-specific properties. Can be null, which means the same thing as passing
in an empty map.
JAXBException
- if an error was encountered while creating the
JAXBContext such as
public static JAXBContext newInstance(java.lang.Class... classesToBeBound) throws JAXBException
Obtain a new instance of a JAXBContext class.
The client application must supply a list of classes that the new
context object needs to recognize.
Not only the new context will recognize all the classes specified,
but it will also recognize any classes that are directly/indirectly
referenced statically from the specified classes. Subclasses of
referenced classes nor @XmlTransient referenced classes
are not registered with JAXBContext.
For example, in the following Java code, if you do
newInstance(Foo.class), the newly created JAXBContext
will recognize both Foo and Bar, but not Zot or FooBar:
class Foo { @XmlTransient FooBar c; Bar b; } class Bar { int x; } class Zot extends Bar { int y; } class FooBar { }Therefore, a typical client application only needs to specify the top-level classes, but it needs to be careful.
Note that for each java package registered with JAXBContext, when the optional package annotations exist, they must be processed. (see JLS 3rd Edition, Section 7.4.1. "Package Annotations").
The steps involved in discovering the JAXB implementation is discussed in the class javadoc.
classesToBeBound
- list of java classes to be recognized by the new JAXBContext
.
Can be empty, in which case a JAXBContext
that only knows about
spec-defined classes will be returned.
JAXBException
- if an error was encountered while creating the
JAXBContext, such as (but not limited to):
java.lang.IllegalArgumentException
- if the parameter contains null
(i.e., newInstance(null);
)public static JAXBContext newInstance(java.lang.Class[] classesToBeBound, java.util.Map<java.lang.String,?> properties) throws JAXBException
Obtain a new instance of a JAXBContext class.
An overloading of newInstance(Class...)
to configure 'properties' for this instantiation of JAXBContext
.
The interpretation of properties is up to implementations. Implementations should throw JAXBException if it finds properties that it doesn't understand.
classesToBeBound
- list of java classes to be recognized by the new JAXBContext
.
Can be empty, in which case a JAXBContext
that only knows about
spec-defined classes will be returned.properties
- provider-specific properties. Can be null, which means the same thing as passing
in an empty map.
JAXBException
- if an error was encountered while creating the
JAXBContext, such as (but not limited to):
java.lang.IllegalArgumentException
- if the parameter contains null
(i.e., newInstance(null,someMap);
)public abstract Unmarshaller createUnmarshaller() throws JAXBException
JAXBException
- if an error was encountered while creating the
Unmarshaller objectpublic abstract Marshaller createMarshaller() throws JAXBException
JAXBException
- if an error was encountered while creating the
Marshaller objectpublic abstract Validator createValidator() throws JAXBException
Validator
has been made optional and deprecated in JAXB 2.0. Please
refer to the javadoc for Validator
for more detail.
Create a Validator object that can be used to validate a java content tree against its source schema.
JAXBException
- if an error was encountered while creating the
Validator objectpublic <T> Binder<T> createBinder(java.lang.Class<T> domType)
domType
- select the DOM API to use by passing in its DOM Node class.
java.lang.UnsupportedOperationException
- if DOM API corresponding to domType is not supported by
the implementation.public Binder<org.w3c.dom.Node> createBinder()
public JAXBIntrospector createJAXBIntrospector()
java.lang.UnsupportedOperationException
- Calling this method on JAXB 1.0 implementations will throw
an UnsupportedOperationException.public void generateSchema(SchemaOutputResolver outputResolver) throws java.io.IOException
outputResolver
- this object controls the output to which schemas
will be sent.
java.io.IOException
- if SchemaOutputResolver
throws an IOException
.
java.lang.UnsupportedOperationException
- Calling this method on JAXB 1.0 implementations will throw
an UnsupportedOperationException.
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EclipseLink 2.2.0, build 'v20110202-r8913' API Reference | ||||||||
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