Spring Framework

org.springframework.util
Class MethodInvoker

java.lang.Object
  extended by org.springframework.util.MethodInvoker
Direct Known Subclasses:
ArgumentConvertingMethodInvoker

public class MethodInvoker
extends java.lang.Object

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.

Since:
19.02.2004
Author:
Colin Sampaleanu, Juergen Hoeller
See Also:
prepare(), invoke()

Constructor Summary
MethodInvoker()
           
 
Method Summary
protected  java.lang.reflect.Method findMatchingMethod()
          Find a matching method with the specified name for the specified arguments.
 java.lang.Object[] getArguments()
          Return the arguments for the method invocation.
 java.lang.reflect.Method getPreparedMethod()
          Return the prepared Method object that will be invoked.
 java.lang.Class getTargetClass()
          Return the target class on which to call the target method.
 java.lang.String getTargetMethod()
          Return the name of the method to be invoked.
 java.lang.Object getTargetObject()
          Return the target object on which to call the target method.
static int getTypeDifferenceWeight(java.lang.Class[] paramTypes, java.lang.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.
 java.lang.Object invoke()
          Invoke the specified method.
 boolean isPrepared()
          Return whether this invoker has been prepared already, i.e.
 void prepare()
          Prepare the specified method.
protected  java.lang.Class resolveClassName(java.lang.String className)
          Resolve the given class name into a Class.
 void setArguments(java.lang.Object[] arguments)
          Set arguments for the method invocation.
 void setStaticMethod(java.lang.String staticMethod)
          Set a fully qualified static method name to invoke, e.g.
 void setTargetClass(java.lang.Class targetClass)
          Set the target class on which to call the target method.
 void setTargetMethod(java.lang.String targetMethod)
          Set the name of the method to be invoked.
 void setTargetObject(java.lang.Object targetObject)
          Set the target object on which to call the target method.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

MethodInvoker

public MethodInvoker()
Method Detail

setTargetClass

public void setTargetClass(java.lang.Class targetClass)
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.

See Also:
setTargetObject(java.lang.Object), setTargetMethod(java.lang.String)

getTargetClass

public java.lang.Class getTargetClass()
Return the target class on which to call the target method.


setTargetObject

public void setTargetObject(java.lang.Object targetObject)
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.

See Also:
setTargetClass(java.lang.Class), setTargetMethod(java.lang.String)

getTargetObject

public java.lang.Object getTargetObject()
Return the target object on which to call the target method.


setTargetMethod

public void setTargetMethod(java.lang.String targetMethod)
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.

See Also:
setTargetClass(java.lang.Class), setTargetObject(java.lang.Object)

getTargetMethod

public java.lang.String getTargetMethod()
Return the name of the method to be invoked.


setStaticMethod

public void setStaticMethod(java.lang.String staticMethod)
Set a fully qualified static method name to invoke, e.g. "example.MyExampleClass.myExampleMethod". Convenient alternative to specifying targetClass and targetMethod.

See Also:
setTargetClass(java.lang.Class), setTargetMethod(java.lang.String)

setArguments

public void setArguments(java.lang.Object[] arguments)
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.


getArguments

public java.lang.Object[] getArguments()
Return the arguments for the method invocation.


prepare

public void prepare()
             throws java.lang.ClassNotFoundException,
                    java.lang.NoSuchMethodException
Prepare the specified method. The method can be invoked any number of times afterwards.

Throws:
java.lang.ClassNotFoundException
java.lang.NoSuchMethodException
See Also:
getPreparedMethod(), invoke()

resolveClassName

protected java.lang.Class resolveClassName(java.lang.String className)
                                    throws java.lang.ClassNotFoundException
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:
java.lang.ClassNotFoundException - if the class name was invalid

findMatchingMethod

protected java.lang.reflect.Method findMatchingMethod()
Find a matching method with the specified name for the specified arguments.

Returns:
a matching method, or null if none
See Also:
getTargetClass(), getTargetMethod(), getArguments()

getPreparedMethod

public java.lang.reflect.Method getPreparedMethod()
                                           throws java.lang.IllegalStateException
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:
java.lang.IllegalStateException - if the invoker hasn't been prepared yet
See Also:
prepare(), invoke()

isPrepared

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


invoke

public java.lang.Object invoke()
                        throws java.lang.reflect.InvocationTargetException,
                               java.lang.IllegalAccessException
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:
java.lang.reflect.InvocationTargetException - if the target method threw an exception
java.lang.IllegalAccessException - if the target method couldn't be accessed
See Also:
prepare()

getTypeDifferenceWeight

public static int getTypeDifferenceWeight(java.lang.Class[] paramTypes,
                                          java.lang.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.

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

Spring Framework