Package org.apache.commons.configuration.beanutils

Class BeanHelper

java.lang.Object

org.apache.commons.configuration.beanutils.BeanHelper

public final class BeanHelper
extends java.lang.Object

A helper class for creating bean instances that are defined in configuration files.

This class provides static utility methods related to bean creation operations. These methods simplify such operations because a client need not deal with all involved interfaces. Usually, if a bean declaration has already been obtained, a single method call is necessary to create a new bean instance.

This class also supports the registration of custom bean factories. Implementations of the BeanFactory interface can be registered under a symbolic name using the registerBeanFactory() method. In the configuration file the name of the bean factory can be specified in the bean declaration. Then this factory will be used to create the bean.

Since:

1.3

Version:

$Id: BeanHelper.java 1534393 2013-10-21 22:02:27Z henning $

Author:

Commons Configuration team

Method Summary

Modifier and Type	Method	Description
static java.lang.Object	createBean(BeanDeclaration data)	Returns a bean instance for the specified declaration.
static java.lang.Object	createBean(BeanDeclaration data, java.lang.Class<?> defaultClass)	Returns a bean instance for the specified declaration.
static java.lang.Object	createBean(BeanDeclaration data, java.lang.Class<?> defaultClass, java.lang.Object param)	The main method for creating and initializing beans from a configuration.
static BeanFactory	deregisterBeanFactory(java.lang.String name)	Deregisters the bean factory with the given name.
static BeanFactory	getDefaultBeanFactory()	Returns the default bean factory.
static void	initBean(java.lang.Object bean, BeanDeclaration data)	Initializes the passed in bean.
static void	initBeanProperties(java.lang.Object bean, BeanDeclaration data)	Initializes the beans properties.
static void	registerBeanFactory(java.lang.String name, BeanFactory factory)	Register a bean factory under a symbolic name.
static java.util.Set<java.lang.String>	registeredFactoryNames()	Returns a set with the names of all currently registered bean factories.
static void	setDefaultBeanFactory(BeanFactory factory)	Sets the default bean factory.
static void	setProperty(java.lang.Object bean, java.lang.String propName, java.lang.Object value)	Set a property on the bean only if the property exists

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

registerBeanFactory

public static void registerBeanFactory(java.lang.String name,
                                       BeanFactory factory)

Register a bean factory under a symbolic name. This factory object can then be specified in bean declarations with the effect that this factory will be used to obtain an instance for the corresponding bean declaration.

Parameters:

name - the name of the factory

factory - the factory to be registered

deregisterBeanFactory

public static BeanFactory deregisterBeanFactory(java.lang.String name)

Deregisters the bean factory with the given name. After that this factory cannot be used any longer.

Parameters:

name - the name of the factory to be deregistered

Returns:

the factory that was registered under this name; null if there was no such factory

registeredFactoryNames

public static java.util.Set<java.lang.String> registeredFactoryNames()

Returns a set with the names of all currently registered bean factories.

Returns:

a set with the names of the registered bean factories

getDefaultBeanFactory

public static BeanFactory getDefaultBeanFactory()

Returns the default bean factory.

Returns:

the default bean factory

setDefaultBeanFactory

public static void setDefaultBeanFactory(BeanFactory factory)

Sets the default bean factory. This factory will be used for all create operations, for which no special factory is provided in the bean declaration.

Parameters:

factory - the default bean factory (must not be null)

initBean

public static void initBean(java.lang.Object bean,
                            BeanDeclaration data)
                     throws ConfigurationRuntimeException

Initializes the passed in bean. This method will obtain all the bean's properties that are defined in the passed in bean declaration. These properties will be set on the bean. If necessary, further beans will be created recursively.

Parameters:

bean - the bean to be initialized

data - the bean declaration

Throws:

ConfigurationRuntimeException - if a property cannot be set

initBeanProperties

public static void initBeanProperties(java.lang.Object bean,
                                      BeanDeclaration data)
                               throws ConfigurationRuntimeException

Initializes the beans properties.

Parameters:

bean - the bean to be initialized

data - the bean declaration

Throws:

ConfigurationRuntimeException - if a property cannot be set

setProperty

public static void setProperty(java.lang.Object bean,
                               java.lang.String propName,
                               java.lang.Object value)

Set a property on the bean only if the property exists

Parameters:

bean - the bean

propName - the name of the property

value - the property's value

Throws:

ConfigurationRuntimeException - if the property is not writeable or an error occurred

createBean

public static java.lang.Object createBean(BeanDeclaration data,
                                          java.lang.Class<?> defaultClass,
                                          java.lang.Object param)
                                   throws ConfigurationRuntimeException

The main method for creating and initializing beans from a configuration. This method will return an initialized instance of the bean class specified in the passed in bean declaration. If this declaration does not contain the class of the bean, the passed in default class will be used. From the bean declaration the factory to be used for creating the bean is queried. The declaration may here return null, then a default factory is used. This factory is then invoked to perform the create operation.

Parameters:

data - the bean declaration

defaultClass - the default class to use

param - an additional parameter that will be passed to the bean factory; some factories may support parameters and behave different depending on the value passed in here

Returns:

the new bean

Throws:

ConfigurationRuntimeException - if an error occurs

createBean

public static java.lang.Object createBean(BeanDeclaration data,
                                          java.lang.Class<?> defaultClass)
                                   throws ConfigurationRuntimeException

Returns a bean instance for the specified declaration. This method is a short cut for createBean(data, null, null);.

Parameters:

data - the bean declaration

defaultClass - the class to be used when in the declaration no class is specified

Returns:

the new bean

Throws:

ConfigurationRuntimeException - if an error occurs

createBean

public static java.lang.Object createBean(BeanDeclaration data)
                                   throws ConfigurationRuntimeException

Returns a bean instance for the specified declaration. This method is a short cut for createBean(data, null);.

Parameters:

data - the bean declaration

Returns:

the new bean

Throws:

ConfigurationRuntimeException - if an error occurs