Class MethodInvokingFactoryBean
- All Implemented Interfaces:
Aware
,BeanClassLoaderAware
,BeanFactoryAware
,FactoryBean<Object>
,InitializingBean
FactoryBean
which returns a value which is the result of a static or instance
method invocation. For most use cases it is better to just use the container's
built-in factory method support for the same purpose, since that is smarter at
converting arguments. This factory bean is still useful though when you need to
call a method which doesn't return any value (for example, a static class method
to force some sort of initialization to happen). This use case is not supported
by factory methods, since a return value is needed to obtain the bean instance.
Note that as it is expected to be used mostly for accessing factory methods,
this factory by default operates in a singleton fashion. The first request
to getObject()
by the owning bean factory will cause a method invocation,
whose return value will be cached for subsequent requests. An internal
singleton
property may be set to "false", to cause this
factory to invoke the target method each time it is asked for an object.
NOTE: If your target method does not produce a result to expose, consider
MethodInvokingBean
instead, which avoids the type determination and
lifecycle limitations that this MethodInvokingFactoryBean
comes with.
This invoker supports any kind of target method. A static method may be specified
by setting the targetMethod
property to a String representing
the static method name, with targetClass
specifying the Class
that the static method is defined on. Alternatively, a target instance method may be
specified, by setting the targetObject
property as the target
object, and the targetMethod
property as the name of the
method to call on that target object. Arguments for the method invocation may be
specified by setting the arguments
property.
This class depends on afterPropertiesSet()
being called once
all properties have been set, as per the InitializingBean contract.
An example (in an XML based bean factory definition) of a bean definition which uses this class to call a static factory method:
<bean id="myObject" class="org.springframework.beans.factory.config.MethodInvokingFactoryBean"> <property name="staticMethod" value="com.whatever.MyClassFactory.getInstance"/> </bean>
An example of calling a static method then an instance method to get at a Java system property. Somewhat verbose, but it works.
<bean id="sysProps" class="org.springframework.beans.factory.config.MethodInvokingFactoryBean"> <property name="targetClass" value="java.lang.System"/> <property name="targetMethod" value="getProperties"/> </bean> <bean id="javaVersion" class="org.springframework.beans.factory.config.MethodInvokingFactoryBean"> <property name="targetObject" ref="sysProps"/> <property name="targetMethod" value="getProperty"/> <property name="arguments" value="java.version"/> </bean>
- Since:
- 21.11.2003
- Author:
- Colin Sampaleanu, Juergen Hoeller
- See Also:
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Field Summary
Fields inherited from class org.springframework.util.MethodInvoker
targetClass
Fields inherited from interface org.springframework.beans.factory.FactoryBean
OBJECT_TYPE_ATTRIBUTE
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionvoid
Invoked by the containingBeanFactory
after it has set all bean properties and satisfiedBeanFactoryAware
,ApplicationContextAware
etc.Returns the same value each time if the singleton property is set to "true", otherwise returns the value returned from invoking the specified method on the fly.Class<?>
Return the type of object that this FactoryBean creates, ornull
if not known in advance.boolean
Is the object managed by this factory a singleton? That is, willFactoryBean.getObject()
always return the same object (a reference that can be cached)?void
setSingleton
(boolean singleton) Set if a singleton should be created, or a new object on eachgetObject()
request otherwise.Methods inherited from class org.springframework.beans.factory.config.MethodInvokingBean
getDefaultTypeConverter, invokeWithTargetException, resolveClassName, setBeanClassLoader, setBeanFactory
Methods inherited from class org.springframework.beans.support.ArgumentConvertingMethodInvoker
doFindMatchingMethod, findMatchingMethod, getTypeConverter, registerCustomEditor, setTypeConverter
Methods inherited from class org.springframework.util.MethodInvoker
getArguments, getPreparedMethod, getTargetClass, getTargetMethod, getTargetObject, getTypeDifferenceWeight, invoke, isPrepared, prepare, setArguments, setStaticMethod, setTargetClass, setTargetMethod, setTargetObject
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Constructor Details
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MethodInvokingFactoryBean
public MethodInvokingFactoryBean()
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Method Details
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setSingleton
public void setSingleton(boolean singleton) Set if a singleton should be created, or a new object on eachgetObject()
request otherwise. Default is "true". -
afterPropertiesSet
Description copied from interface:InitializingBean
Invoked by the containingBeanFactory
after it has set all bean properties and satisfiedBeanFactoryAware
,ApplicationContextAware
etc.This method allows the bean instance to perform validation of its overall configuration and final initialization when all bean properties have been set.
- Specified by:
afterPropertiesSet
in interfaceInitializingBean
- Overrides:
afterPropertiesSet
in classMethodInvokingBean
- Throws:
Exception
- in the event of misconfiguration (such as failure to set an essential property) or if initialization fails for any other reason
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getObject
Returns the same value each time if the singleton property is set to "true", otherwise returns the value returned from invoking the specified method on the fly.- Specified by:
getObject
in interfaceFactoryBean<Object>
- Returns:
- an instance of the bean (can be
null
) - Throws:
Exception
- in case of creation errors- See Also:
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getObjectType
Return the type of object that this FactoryBean creates, ornull
if not known in advance.- Specified by:
getObjectType
in interfaceFactoryBean<Object>
- Returns:
- the type of object that this FactoryBean creates,
or
null
if not known at the time of the call - See Also:
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isSingleton
public boolean isSingleton()Description copied from interface:FactoryBean
Is the object managed by this factory a singleton? That is, willFactoryBean.getObject()
always return the same object (a reference that can be cached)?NOTE: If a FactoryBean indicates to hold a singleton object, the object returned from
getObject()
might get cached by the owning BeanFactory. Hence, do not returntrue
unless the FactoryBean always exposes the same reference.The singleton status of the FactoryBean itself will generally be provided by the owning BeanFactory; usually, it has to be defined as singleton there.
NOTE: This method returning
false
does not necessarily indicate that returned objects are independent instances. An implementation of the extendedSmartFactoryBean
interface may explicitly indicate independent instances through itsSmartFactoryBean.isPrototype()
method. PlainFactoryBean
implementations which do not implement this extended interface are simply assumed to always return independent instances if theisSingleton()
implementation returnsfalse
.The default implementation returns
true
, since aFactoryBean
typically manages a singleton instance.- Specified by:
isSingleton
in interfaceFactoryBean<Object>
- Returns:
- whether the exposed object is a singleton
- See Also:
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