Interface NamespaceHandler

All Known Implementing Classes:

AopNamespaceHandler, CacheNamespaceHandler, ContextNamespaceHandler, JdbcNamespaceHandler, JeeNamespaceHandler, JmsNamespaceHandler, LangNamespaceHandler, MvcNamespaceHandler, NamespaceHandlerSupport, OxmNamespaceHandler, SimpleConstructorNamespaceHandler, SimplePropertyNamespaceHandler, TaskNamespaceHandler, TxNamespaceHandler, UtilNamespaceHandler, WebSocketNamespaceHandler

public interface NamespaceHandler

Base interface used by the DefaultBeanDefinitionDocumentReader for handling custom namespaces in a Spring XML configuration file.

Implementations are expected to return implementations of the BeanDefinitionParser interface for custom top-level tags and implementations of the BeanDefinitionDecorator interface for custom nested tags.

The parser will call parse(Element, ParserContext) when it encounters a custom tag directly under the <beans> tags and decorate(Node, BeanDefinitionHolder, ParserContext) when it encounters a custom tag directly under a <bean> tag.

Developers writing their own custom element extensions typically will not implement this interface directly, but rather make use of the provided NamespaceHandlerSupport class.

Since:

2.0

Author:

Rob Harrop, Erik Wiersma

See Also:

• DefaultBeanDefinitionDocumentReader
• NamespaceHandlerResolver

Method Summary

Modifier and Type	Method	Description
@Nullable BeanDefinitionHolder	decorate(Node source, BeanDefinitionHolder definition, ParserContext parserContext)	Parse the specified Node and decorate the supplied BeanDefinitionHolder, returning the decorated definition.
void	init()	Invoked by the DefaultBeanDefinitionDocumentReader after construction but before any custom elements are parsed.
@Nullable BeanDefinition	parse(Element element, ParserContext parserContext)	Parse the specified Element and register any resulting BeanDefinitions with the BeanDefinitionRegistry that is embedded in the supplied ParserContext.

Method Details

init

void init()

Invoked by the DefaultBeanDefinitionDocumentReader after construction but before any custom elements are parsed.

See Also:

• NamespaceHandlerSupport.registerBeanDefinitionParser(String, BeanDefinitionParser)

parse

@Nullable BeanDefinition parse(Element element,
 ParserContext parserContext)

Parse the specified Element and register any resulting BeanDefinitions with the BeanDefinitionRegistry that is embedded in the supplied ParserContext.

Implementations should return the primary BeanDefinition that results from the parse phase if they wish to be used nested inside (for example) a <property> tag.

Implementations may return null if they will not be used in a nested scenario.

Parameters:

element - the element that is to be parsed into one or more BeanDefinitions

parserContext - the object encapsulating the current state of the parsing process

Returns:

the primary BeanDefinition (can be null as explained above)

decorate

@Nullable BeanDefinitionHolder decorate(Node source,
 BeanDefinitionHolder definition,
 ParserContext parserContext)

Parse the specified Node and decorate the supplied BeanDefinitionHolder, returning the decorated definition.

The Node may be either an Attr or an Element, depending on whether a custom attribute or element is being parsed.

Implementations may choose to return a completely new definition, which will replace the original definition in the resulting BeanFactory.

The supplied ParserContext can be used to register any additional beans needed to support the main definition.

Parameters:

source - the source element or attribute that is to be parsed

definition - the current bean definition

parserContext - the object encapsulating the current state of the parsing process

Returns:

the decorated definition (to be registered in the BeanFactory), or simply the original bean definition if no decoration is required. A null value is strictly speaking invalid, but will be leniently treated like the case where the original bean definition gets returned.