| Convenient base class for when there exists a one-to-one mapping
between attribute names on the element that is to be parsed and
the property names on the
Class being configured.
Extend this parser class when you want to create a single
bean definition from a relatively simple custom XML element. The
resulting BeanDefinition will be automatically
registered with the relevant
org.springframework.beans.factory.support.BeanDefinitionRegistry .
An example will hopefully make the use of this particular parser
class immediately clear. Consider the following class definition:
public class SimpleCache implements Cache {
public void setName(String name) {...}
public void setTimeout(int timeout) {...}
public void setEvictionPolicy(EvictionPolicy policy) {...}
// remaining class definition elided for clarity...
}
Then let us assume the following XML tag has been defined to
permit the easy configuration of instances of the above class;
<caching:cache name="..." timeout="..." eviction-policy="..."/>
All that is required of the Java developer tasked with writing
the parser to parse the above XML tag into an actual
SimpleCache bean definition is the following:
public class SimpleCacheBeanDefinitionParser extends AbstractSimpleBeanDefinitionParser {
protected Class getBeanClass(Element element) {
return SimpleCache.class;
}
}
Please note that the AbstractSimpleBeanDefinitionParser
is limited to populating the created bean definition with property values.
if you want to parse constructor arguments and nested elements from the
supplied XML element, then you will have to implement the
AbstractSimpleBeanDefinitionParser.postProcess(org.springframework.beans.factory.support.BeanDefinitionBuilder,org.w3c.dom.Element) method and do such parsing yourself, or (more likely) subclass the
AbstractSingleBeanDefinitionParser or
AbstractBeanDefinitionParser classes directly.
The process of actually registering the
SimpleCacheBeanDefinitionParser with the Spring XML parsing
infrastructure is described in the Spring Framework reference documentation
(in one of the appendices).
For an example of this parser in action (so to speak), do look at
the source code for the
org.springframework.beans.factory.xml.UtilNamespaceHandler.PropertiesBeanDefinitionParser ;
the observant (and even not so observant) reader will immediately notice that
there is next to no code in the implementation. The
PropertiesBeanDefinitionParser populates a
org.springframework.beans.factory.config.PropertiesFactoryBean from an XML element that looks like this:
<util:properties location="jdbc.properties"/>
The observant reader will notice that the sole attribute on the
<util:properties/> element matches the
org.springframework.beans.factory.config.PropertiesFactoryBean.setLocation(org.springframework.core.io.Resource) method name on the PropertiesFactoryBean (the general
usage thus illustrated holds true for any number of attributes).
All that the PropertiesBeanDefinitionParser needs
actually do is supply an implementation of the
AbstractSimpleBeanDefinitionParser.getBeanClass(org.w3c.dom.Element) method to return the
PropertiesFactoryBean type.
author:
Rob Harrop
author:
Rick Evans
author:
Juergen Hoeller
since:
2.0
See Also: Conventions.attributeNameToPropertyName(String) | 