MethodInvokingFactoryBean

Class Overview

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>

Summary

[Expand] Inherited Methods
From class org.springframework.beans.support.ArgumentConvertingMethodInvoker Method doFindMatchingMethod(Object[] arguments) Actually find a method with matching parameter type, i.e. Method findMatchingMethod() This implementation looks for a method with matching parameter types. TypeConverter getDefaultTypeConverter() Obtain the default TypeConverter for this method invoker. TypeConverter getTypeConverter() Return the TypeConverter used for argument type conversion. void registerCustomEditor(Class requiredType, PropertyEditor propertyEditor) Register the given custom property editor for all properties of the given type. void setTypeConverter(TypeConverter typeConverter) Set a TypeConverter to use for argument type conversion.
From class org.springframework.util.MethodInvoker Method findMatchingMethod() Find a matching method with the specified name for the specified arguments. Object[] getArguments() Return the arguments for the method invocation. Method getPreparedMethod() Return the prepared Method object that will be invoked. Class getTargetClass() Return the target class on which to call the target method. String getTargetMethod() Return the name of the method to be invoked. Object getTargetObject() Return the target object on which to call the target method. static int getTypeDifferenceWeight(Class[] paramTypes, Object[] args) Algorithm that judges the match between the declared parameter types of a candidate method and a specific list of arguments that this method is supposed to be invoked with. Object invoke() Invoke the specified method. boolean isPrepared() Return whether this invoker has been prepared already, i.e. void prepare() Prepare the specified method. Class resolveClassName(String className) Resolve the given class name into a Class. void setArguments(Object[] arguments) Set arguments for the method invocation. void setStaticMethod(String staticMethod) Set a fully qualified static method name to invoke, e.g. void setTargetClass(Class targetClass) Set the target class on which to call the target method. void setTargetMethod(String targetMethod) Set the name of the method to be invoked. void setTargetObject(Object targetObject) Set the target object on which to call the target method.
From class java.lang.Object Object clone() boolean equals(Object arg0) void finalize() final Class<?> getClass() int hashCode() final void notify() final void notifyAll() String toString() final void wait() final void wait(long arg0, int arg1) final void wait(long arg0)
From interface org.springframework.beans.factory.BeanClassLoaderAware abstract void setBeanClassLoader(ClassLoader classLoader) Callback that supplies the bean class loader to a bean instance.
From interface org.springframework.beans.factory.BeanFactoryAware abstract void setBeanFactory(BeanFactory beanFactory) Callback that supplies the owning factory to a bean instance.
From interface org.springframework.beans.factory.FactoryBean abstract T getObject() Return an instance (possibly shared or independent) of the object managed by this factory. abstract Class<?> getObjectType() Return the type of object that this FactoryBean creates, or null if not known in advance. abstract boolean isSingleton() Is the object managed by this factory a singleton? That is, will 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.
From interface org.springframework.beans.factory.InitializingBean abstract void afterPropertiesSet() Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware).