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java.lang.Object org.springframework.util.MethodInvoker org.springframework.beans.support.ArgumentConvertingMethodInvoker org.springframework.beans.factory.config.MethodInvokingFactoryBean
public class MethodInvokingFactoryBean
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.
A static target 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</value></property> </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</value></property> <property name="targetMethod"><value>getProperties</value></property> </bean> <bean id="javaVersion" class="org.springframework.beans.factory.config.MethodInvokingFactoryBean"> <property name="targetObject"><ref local="sysProps"/></property> <property name="targetMethod"><value>getProperty</value></property> <property name="arguments"> <list> <value>java.version</value> </list> </property> </bean>
Constructor Summary | |
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MethodInvokingFactoryBean()
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Method Summary | |
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void |
afterPropertiesSet()
Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware). |
protected TypeConverter |
getDefaultTypeConverter()
Obtain the TypeConverter from the BeanFactory that this bean runs in, if possible. |
Object |
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. |
Class |
getObjectType()
Return the type of object that this FactoryBean creates, or null if not known in advance. |
boolean |
isSingleton()
Is the object managed by this factory a singleton? |
protected Class |
resolveClassName(String className)
Resolve the given class name into a Class. |
void |
setBeanClassLoader(ClassLoader classLoader)
Callback that supplies the bean class loader to
a bean instance. |
void |
setBeanFactory(BeanFactory beanFactory)
Callback that supplies the owning factory to a bean instance. |
void |
setSingleton(boolean singleton)
Set if a singleton should be created, or a new object on each request else. |
Methods inherited from class org.springframework.beans.support.ArgumentConvertingMethodInvoker |
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findMatchingMethod, getTypeConverter, registerCustomEditor, setTypeConverter |
Methods inherited from class org.springframework.util.MethodInvoker |
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getArguments, getPreparedMethod, getTargetClass, getTargetMethod, getTargetObject, invoke, isPrepared, prepare, setArguments, setStaticMethod, setTargetClass, setTargetMethod, setTargetObject |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public MethodInvokingFactoryBean()
Method Detail |
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public void setSingleton(boolean singleton)
public boolean isSingleton()
FactoryBean
FactoryBean.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 return true
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 extended SmartFactoryBean
interface
may explicitly indicate independent instances through its
SmartFactoryBean.isPrototype()
method. Plain FactoryBean
implementations which do not implement this extended interface are
simply assumed to always return independent instances if the
isSingleton()
implementation returns false
.
isSingleton
in interface FactoryBean
FactoryBean.getObject()
,
SmartFactoryBean.isPrototype()
public void setBeanClassLoader(ClassLoader classLoader)
BeanClassLoaderAware
class loader
to
a bean instance.
Invoked after the population of normal bean properties but
before an initialization callback such as
InitializingBean's
InitializingBean.afterPropertiesSet()
method or a custom init-method.
setBeanClassLoader
in interface BeanClassLoaderAware
classLoader
- the owning class loader; may be null
in
which case a default ClassLoader
must be used, for example
the ClassLoader
obtained via
ClassUtils.getDefaultClassLoader()
protected Class resolveClassName(String className) throws ClassNotFoundException
MethodInvoker
The default implementations uses ClassUtils.forName
,
using the thread context class loader.
resolveClassName
in class MethodInvoker
className
- the class name to resolve
ClassNotFoundException
- if the class name was invalidpublic void setBeanFactory(BeanFactory beanFactory)
BeanFactoryAware
Invoked after the population of normal bean properties
but before an initialization callback such as
InitializingBean.afterPropertiesSet()
or a custom init-method.
setBeanFactory
in interface BeanFactoryAware
beanFactory
- owning BeanFactory (never null
).
The bean can immediately call methods on the factory.BeanInitializationException
protected TypeConverter getDefaultTypeConverter()
getDefaultTypeConverter
in class ArgumentConvertingMethodInvoker
public void afterPropertiesSet() throws Exception
InitializingBean
This method allows the bean instance to perform initialization only possible when all bean properties have been set and to throw an exception in the event of misconfiguration.
afterPropertiesSet
in interface InitializingBean
Exception
- in the event of misconfiguration (such
as failure to set an essential property) or if initialization fails.public Object getObject() throws Exception
getObject
in interface FactoryBean
null
)
Exception
- in case of creation errorsFactoryBeanNotInitializedException
public Class getObjectType()
null
if not known in advance.
getObjectType
in interface FactoryBean
null
if not known at the time of the callListableBeanFactory.getBeansOfType(java.lang.Class)
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