public class

MethodInvoker

extends Object
java.lang.Object
   ↳ org.springframework.util.MethodInvoker
Known Direct Subclasses
Known Indirect Subclasses

Class Overview

Helper class that allows for specifying a method to invoke in a declarative fashion, be it static or non-static.

Usage: Specify "targetClass"/"targetMethod" or "targetObject"/"targetMethod", optionally specify arguments, prepare the invoker. Afterwards, you may invoke the method any number of times, obtaining the invocation result.

Typically not used directly but via its subclasses MethodInvokingFactoryBean and MethodInvokingJobDetailFactoryBean.

Summary

Public Constructors
MethodInvoker()
Public Methods
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.
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.
Protected Methods
Method findMatchingMethod()
Find a matching method with the specified name for the specified arguments.
Class resolveClassName(String className)
Resolve the given class name into a Class.
[Expand]
Inherited Methods
From class java.lang.Object

Public Constructors

public MethodInvoker ()

Also: SpringCore

Public Methods

public Object[] getArguments ()

Also: SpringCore

Return the arguments for the method invocation.

public Method getPreparedMethod ()

Also: SpringCore

Return the prepared Method object that will be invoked.

Can for example be used to determine the return type.

Returns
  • the prepared Method object (never null)
Throws
IllegalStateException if the invoker hasn't been prepared yet

public Class getTargetClass ()

Also: SpringCore

Return the target class on which to call the target method.

public String getTargetMethod ()

Also: SpringCore

Return the name of the method to be invoked.

public Object getTargetObject ()

Also: SpringCore

Return the target object on which to call the target method.

public static int getTypeDifferenceWeight (Class[] paramTypes, Object[] args)

Also: SpringCore

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.

Determines a weight that represents the class hierarchy difference between types and arguments. A direct match, i.e. type Integer -> arg of class Integer, does not increase the result - all direct matches means weight 0. A match between type Object and arg of class Integer would increase the weight by 2, due to the superclass 2 steps up in the hierarchy (i.e. Object) being the last one that still matches the required type Object. Type Number and class Integer would increase the weight by 1 accordingly, due to the superclass 1 step up the hierarchy (i.e. Number) still matching the required type Number. Therefore, with an arg of type Integer, a constructor (Integer) would be preferred to a constructor (Number) which would in turn be preferred to a constructor (Object). All argument weights get accumulated.

Parameters
paramTypes the parameter types to match
args the arguments to match
Returns
  • the accumulated weight for all arguments

public Object invoke ()

Also: SpringCore

Invoke the specified method.

The invoker needs to have been prepared before.

Returns
  • the object (possibly null) returned by the method invocation, or null if the method has a void return type
Throws
InvocationTargetException if the target method threw an exception
IllegalAccessException if the target method couldn't be accessed
See Also

public boolean isPrepared ()

Also: SpringCore

Return whether this invoker has been prepared already, i.e. whether it allows access to getPreparedMethod() already.

public void prepare ()

Also: SpringCore

Prepare the specified method. The method can be invoked any number of times afterwards.

public void setArguments (Object[] arguments)

Also: SpringCore

Set arguments for the method invocation. If this property is not set, or the Object array is of length 0, a method with no arguments is assumed.

public void setStaticMethod (String staticMethod)

Also: SpringCore

Set a fully qualified static method name to invoke, e.g. "example.MyExampleClass.myExampleMethod". Convenient alternative to specifying targetClass and targetMethod.

public void setTargetClass (Class targetClass)

Also: SpringCore

Set the target class on which to call the target method. Only necessary when the target method is static; else, a target object needs to be specified anyway.

public void setTargetMethod (String targetMethod)

Also: SpringCore

Set the name of the method to be invoked. Refers to either a static method or a non-static method, depending on a target object being set.

public void setTargetObject (Object targetObject)

Also: SpringCore

Set the target object on which to call the target method. Only necessary when the target method is not static; else, a target class is sufficient.

Protected Methods

protected Method findMatchingMethod ()

Also: SpringCore

Find a matching method with the specified name for the specified arguments.

Returns
  • a matching method, or null if none

protected Class resolveClassName (String className)

Also: SpringCore

Resolve the given class name into a Class.

The default implementations uses ClassUtils.forName, using the thread context class loader.

Parameters
className the class name to resolve
Returns
  • the resolved Class
Throws
ClassNotFoundException if the class name was invalid