Class XMLBeanDeclaration

java.lang.Object
org.apache.commons.configuration.beanutils.XMLBeanDeclaration
All Implemented Interfaces:
BeanDeclaration
Direct Known Subclasses:
DefaultConfigurationBuilder.ConfigurationDeclaration
public class XMLBeanDeclaration extends Object implements BeanDeclaration

An implementation of the BeanDeclaration interface that is suitable for XML configuration files.

This class defines the standard layout of a bean declaration in an XML configuration file. Such a declaration must look like the following example fragment: 

  ...
  <personBean config-class="my.model.PersonBean"
      lastName="Doe" firstName="John">
      <address config-class="my.model.AddressBean"
          street="21st street 11" zip="1234"
          city="TestCity"/>
  </personBean>

The bean declaration can be contained in an arbitrary element. Here it is the personBean element. In the attributes of this element there can occur some reserved attributes, which have the following meaning:

config-class
Here the full qualified name of the bean's class can be specified. An instance of this class will be created. If this attribute is not specified, the bean class must be provided in another way, e.g. as the defaultClass passed to the BeanHelper class.
config-factory
This attribute can contain the name of the BeanFactory that should be used for creating the bean. If it is defined, a factory with this name must have been registered at the BeanHelper class. If this attribute is missing, the default bean factory will be used.
config-factoryParam
With this attribute a parameter can be specified that will be passed to the bean factory. This may be useful for custom bean factories.

All further attributes starting with the config- prefix are considered as meta data and will be ignored. All other attributes are treated as properties of the bean to be created, i.e. corresponding setter methods of the bean will be invoked with the values specified here.

If the bean to be created has also some complex properties (which are itself beans), their values cannot be initialized from attributes. For this purpose nested elements can be used. The example listing shows how an address bean can be initialized. This is done in a nested element whose name must match the name of a property of the enclosing bean declaration. The format of this nested element is exactly the same as for the bean declaration itself, i.e. it can have attributes defining meta data or bean properties and even further nested elements for complex bean properties.

A XMLBeanDeclaration object is usually created from a HierarchicalConfiguration. From this it will derive a SubnodeConfiguration, which is used to access the needed properties. This subnode configuration can be obtained using the getConfiguration() method. All of its properties can be accessed in the usual way. To ensure that the property keys used by this class are understood by the configuration, the default expression engine will be set.

Since:
1.3
Version:
$Id: XMLBeanDeclaration.java 1301959 2012-03-17 16:43:18Z oheger $
Author:
Commons Configuration team

  • Field Details

  • Constructor Details

    • XMLBeanDeclaration

      public XMLBeanDeclaration(HierarchicalConfiguration config, String key)
      Creates a new instance of XMLBeanDeclaration and initializes it from the given configuration. The passed in key points to the bean declaration.
      Parameters:
      config - the configuration
      key - the key to the bean declaration (this key must point to exactly one bean declaration or a IllegalArgumentException exception will be thrown)

    • XMLBeanDeclaration

      public XMLBeanDeclaration(HierarchicalConfiguration config, String key, boolean optional)
      Creates a new instance of XMLBeanDeclaration and initializes it from the given configuration. The passed in key points to the bean declaration. If the key does not exist and the boolean argument is true, the declaration is initialized with an empty configuration. It is possible to create objects from such an empty declaration if a default class is provided. If the key on the other hand has multiple values or is undefined and the boolean argument is false, a IllegalArgumentException exception will be thrown.
      Parameters:
      config - the configuration
      key - the key to the bean declaration
      optional - a flag whether this declaration is optional; if set to true, no exception will be thrown if the passed in key is undefined

    • XMLBeanDeclaration

      public XMLBeanDeclaration(HierarchicalConfiguration config)
      Creates a new instance of XMLBeanDeclaration and initializes it from the given configuration. The configuration's root node must contain the bean declaration.
      Parameters:
      config - the configuration with the bean declaration

    • XMLBeanDeclaration

      public XMLBeanDeclaration(SubnodeConfiguration config, ConfigurationNode node)
      Creates a new instance of XMLBeanDeclaration and initializes it with the configuration node that contains the bean declaration.
      Parameters:
      config - the configuration
      node - the node with the bean declaration.

  • Method Details

    • getConfiguration

      public SubnodeConfiguration getConfiguration()
      Returns the configuration object this bean declaration is based on.
      Returns:
      the associated configuration

    • getNode

      public ConfigurationNode getNode()
      Returns the node that contains the bean declaration.
      Returns:
      the configuration node this bean declaration is based on

    • getBeanFactoryName

      public String getBeanFactoryName()
      Returns the name of the bean factory. This information is fetched from the config-factory attribute.
      Specified by:
      getBeanFactoryName in interface BeanDeclaration
      Returns:
      the name of the bean factory

    • getBeanFactoryParameter

      public Object getBeanFactoryParameter()
      Returns a parameter for the bean factory. This information is fetched from the config-factoryParam attribute.
      Specified by:
      getBeanFactoryParameter in interface BeanDeclaration
      Returns:
      the parameter for the bean factory

    • getBeanClassName

      public String getBeanClassName()
      Returns the name of the class of the bean to be created. This information is obtained from the config-class attribute.
      Specified by:
      getBeanClassName in interface BeanDeclaration
      Returns:
      the name of the bean's class

    • getBeanProperties

      public Map<String,Object> getBeanProperties()
      Returns a map with the bean's (simple) properties. The properties are collected from all attribute nodes, which are not reserved.
      Specified by:
      getBeanProperties in interface BeanDeclaration
      Returns:
      a map with the bean's properties

    • getNestedBeanDeclarations

      public Map<String,Object> getNestedBeanDeclarations()
      Returns a map with bean declarations for the complex properties of the bean to be created. These declarations are obtained from the child nodes of this declaration's root node.
      Specified by:
      getNestedBeanDeclarations in interface BeanDeclaration
      Returns:
      a map with bean declarations for complex properties

    • interpolate

      protected Object interpolate(Object value)
      Performs interpolation for the specified value. This implementation will interpolate against the current subnode configuration's parent. If sub classes need a different interpolation mechanism, they should override this method.
      Parameters:
      value - the value that is to be interpolated
      Returns:
      the interpolated value

    • isReservedNode

      protected boolean isReservedNode(ConfigurationNode nd)
      Checks if the specified node is reserved and thus should be ignored. This method is called when the maps for the bean's properties and complex properties are collected. It checks whether the given node is an attribute node and if its name starts with the reserved prefix.
      Parameters:
      nd - the node to be checked
      Returns:
      a flag whether this node is reserved (and does not point to a property)

    • createBeanDeclaration

      protected BeanDeclaration createBeanDeclaration(ConfigurationNode node)
      Creates a new BeanDeclaration for a child node of the current configuration node. This method is called by getNestedBeanDeclarations() for all complex sub properties detected by this method. Derived classes can hook in if they need a specific initialization. This base implementation creates a XMLBeanDeclaration that is properly initialized from the passed in node.
      Parameters:
      node - the child node, for which a BeanDeclaration is to be created
      Returns:
      the BeanDeclaration for this child node
      Since:
      1.6