Class MethodUtils

java.lang.Object
org.apache.commons.beanutils.MethodUtils
public class MethodUtils extends Object

Utility reflection methods focused on methods in general rather than properties in particular.

Known Limitations: Accessing Public Methods In A Default Access Superclass

There is an issue when invoking public methods contained in a default access superclass. Reflection locates these methods fine and correctly assigns them as public. However, an IllegalAccessException is thrown if the method is invoked.

MethodUtils contains a workaround for this situation. It will attempt to call setAccessible on this method. If this call succeeds, then the method can be invoked as normal. This call will only succeed when the application has sufficient security privileges. If this call fails then a warning will be logged and the method may fail.

  • Field Details

    • loggedAccessibleWarning

      private static boolean loggedAccessibleWarning
      Only log warning about accessibility work around once.

      Note that this is broken when this class is deployed via a shared classloader in a container, as the warning message will be emitted only once, not once per webapp. However making the warning appear once per webapp means having a map keyed by context classloader which introduces nasty memory-leak problems. As this warning is really optional we can ignore this problem; only one of the webapps will get the warning in its logs but that should be good enough.

    • CACHE_METHODS

      private static boolean CACHE_METHODS
      Indicates whether methods should be cached for improved performance.

      Note that when this class is deployed via a shared classloader in a container, this will affect all webapps. However making this configurable per webapp would mean having a map keyed by context classloader which may introduce memory-leak problems.

    • EMPTY_CLASS_PARAMETERS

      private static final Class<?>[] EMPTY_CLASS_PARAMETERS
      An empty class array

    • EMPTY_OBJECT_ARRAY

      private static final Object[] EMPTY_OBJECT_ARRAY
      An empty object array

    • cache

      private static final Map<MethodUtils.MethodDescriptor, Reference<Method>> cache
      Stores a cache of MethodDescriptor to Method in a WeakHashMap.

      The keys into this map only ever exist as temporary variables within methods of this class, and are never exposed to users of this class. This means that the WeakHashMap is used only as a mechanism for limiting the size of the cache, ie a way to tell the garbage collector that the contents of the cache can be completely garbage-collected whenever it needs the memory. Whether this is a good approach to this problem is doubtful; something like the commons-collections LRUMap may be more appropriate (though of course selecting an appropriate size is an issue).

      This static variable is safe even when this code is deployed via a shared classloader because it is keyed via a MethodDescriptor object which has a Class as one of its members and that member is used in the MethodDescriptor.equals method. So two components that load the same class via different classloaders will generate non-equal MethodDescriptor objects and hence end up with different entries in the map.

  • Constructor Details

    • MethodUtils

      @Deprecated public MethodUtils()
      Deprecated.
      Will be private in 2.0.
      Deprecated, all methods are static.

  • Method Details

    • cacheMethod

      private static void cacheMethod(MethodUtils.MethodDescriptor md, Method method)
      Add a method to the cache.
      Parameters:
      md - The method descriptor
      method - The method to cache

    • clearCache

      public static int clearCache()
      Clear the method cache.
      Returns:
      the number of cached methods cleared
      Since:
      1.8.0

    • getAccessibleMethod

      public static Method getAccessibleMethod(Class<?> clazz, Method method)

      Return an accessible method (that is, one that can be invoked via reflection) that implements the specified Method. If no such method can be found, return null.

      Parameters:
      clazz - The class of the object
      method - The method that we wish to call
      Returns:
      The accessible method
      Since:
      1.8.0

    • getAccessibleMethod

      public static Method getAccessibleMethod(Class<?> clazz, String methodName, Class<?> parameterType)

      Return an accessible method (that is, one that can be invoked via reflection) with given name and a single parameter. If no such method can be found, return null. Basically, a convenience wrapper that constructs a Class array for you.

      Parameters:
      clazz - get method from this class
      methodName - get method with this name
      parameterType - taking this type of parameter
      Returns:
      The accessible method

    • getAccessibleMethod

      public static Method getAccessibleMethod(Class<?> clazz, String methodName, Class<?>[] parameterTypes)

      Return an accessible method (that is, one that can be invoked via reflection) with given name and parameters. If no such method can be found, return null. This is just a convenient wrapper for getAccessibleMethod(Method method).

      Parameters:
      clazz - get method from this class
      methodName - get method with this name
      parameterTypes - with these parameters types
      Returns:
      The accessible method

    • getAccessibleMethod

      public static Method getAccessibleMethod(Method method)

      Return an accessible method (that is, one that can be invoked via reflection) that implements the specified Method. If no such method can be found, return null.

      Parameters:
      method - The method that we wish to call
      Returns:
      The accessible method

    • getAccessibleMethodFromInterfaceNest

      private static Method getAccessibleMethodFromInterfaceNest(Class<?> clazz, String methodName, Class<?>[] parameterTypes)

      Return an accessible method (that is, one that can be invoked via reflection) that implements the specified method, by scanning through all implemented interfaces and subinterfaces. If no such method can be found, return null.

      There isn't any good reason why this method must be private. It is because there doesn't seem any reason why other classes should call this rather than the higher level methods.

      Parameters:
      clazz - Parent class for the interfaces to be checked
      methodName - Method name of the method we wish to call
      parameterTypes - The parameter type signatures

    • getAccessibleMethodFromSuperclass

      private static Method getAccessibleMethodFromSuperclass(Class<?> clazz, String methodName, Class<?>[] parameterTypes)

      Return an accessible method (that is, one that can be invoked via reflection) by scanning through the superclasses. If no such method can be found, return null.

      Parameters:
      clazz - Class to be checked
      methodName - Method name of the method we wish to call
      parameterTypes - The parameter type signatures

    • getCachedMethod

      private static Method getCachedMethod(MethodUtils.MethodDescriptor md)
      Return the method from the cache, if present.
      Parameters:
      md - The method descriptor
      Returns:
      The cached method

    • getMatchingAccessibleMethod

      public static Method getMatchingAccessibleMethod(Class<?> clazz, String methodName, Class<?>[] parameterTypes)

      Find an accessible method that matches the given name and has compatible parameters. Compatible parameters mean that every method parameter is assignable from the given parameters. In other words, it finds a method with the given name that will take the parameters given.

      This method is slightly undeterministic since it loops through methods names and return the first matching method.

      This method is used by invokeMethod(Object object,String methodName,Object [] args,Class[] parameterTypes).

      This method can match primitive parameter by passing in wrapper classes. For example, a Boolean will match a primitive boolean parameter.

      Parameters:
      clazz - find method in this class
      methodName - find method with this name
      parameterTypes - find method with compatible parameters
      Returns:
      The accessible method

    • getObjectTransformationCost

      private static float getObjectTransformationCost(Class<?> srcClass, Class<?> destClass)
      Gets the number of steps required needed to turn the source class into the destination class. This represents the number of steps in the object hierarchy graph.
      Parameters:
      srcClass - The source class
      destClass - The destination class
      Returns:
      The cost of transforming an object

    • getPrimitiveType

      public static Class<?> getPrimitiveType(Class<?> wrapperType)
      Gets the class for the primitive type corresponding to the primitive wrapper class given. For example, an instance of Boolean.class returns a boolean.class.
      Parameters:
      wrapperType - the
      Returns:
      the primitive type class corresponding to the given wrapper class, null if no match is found

    • getPrimitiveWrapper

      public static Class<?> getPrimitiveWrapper(Class<?> primitiveType)
      Gets the wrapper object class for the given primitive type class. For example, passing boolean.class returns Boolean.class
      Parameters:
      primitiveType - the primitive type class for which a match is to be found
      Returns:
      the wrapper type associated with the given primitive or null if no match is found

    • getTotalTransformationCost

      private static float getTotalTransformationCost(Class<?>[] srcArgs, Class<?>[] destArgs)
      Returns the sum of the object transformation cost for each class in the source argument list.
      Parameters:
      srcArgs - The source arguments
      destArgs - The destination arguments
      Returns:
      The total transformation cost

    • invokeExactMethod

      public static Object invokeExactMethod(Object object, String methodName, Object arg) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException

      Invoke a method whose parameter type matches exactly the object type.

      This is a convenient wrapper for invokeExactMethod(Object object,String methodName,Object [] args).

      Parameters:
      object - invoke method on this object
      methodName - get method with this name
      arg - use this argument. May be null (this will result in calling the parameterless method with name methodName).
      Returns:
      The value returned by the invoked method
      Throws:
      NoSuchMethodException - if there is no such accessible method
      InvocationTargetException - wraps an exception thrown by the method invoked
      IllegalAccessException - if the requested method is not accessible via reflection

    • invokeExactMethod

      public static Object invokeExactMethod(Object object, String methodName, Object[] args) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException

      Invoke a method whose parameter types match exactly the object types.

      This uses reflection to invoke the method obtained from a call to getAccessibleMethod().

      Parameters:
      object - invoke method on this object
      methodName - get method with this name
      args - use these arguments - treat null as empty array (passing null will result in calling the parameterless method with name methodName).
      Returns:
      The value returned by the invoked method
      Throws:
      NoSuchMethodException - if there is no such accessible method
      InvocationTargetException - wraps an exception thrown by the method invoked
      IllegalAccessException - if the requested method is not accessible via reflection

    • invokeExactMethod

      public static Object invokeExactMethod(Object object, String methodName, Object[] args, Class<?>[] parameterTypes) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException

      Invoke a method whose parameter types match exactly the parameter types given.

      This uses reflection to invoke the method obtained from a call to getAccessibleMethod().

      Parameters:
      object - invoke method on this object
      methodName - get method with this name
      args - use these arguments - treat null as empty array (passing null will result in calling the parameterless method with name methodName).
      parameterTypes - match these parameters - treat null as empty array
      Returns:
      The value returned by the invoked method
      Throws:
      NoSuchMethodException - if there is no such accessible method
      InvocationTargetException - wraps an exception thrown by the method invoked
      IllegalAccessException - if the requested method is not accessible via reflection

    • invokeExactStaticMethod

      public static Object invokeExactStaticMethod(Class<?> objectClass, String methodName, Object arg) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException

      Invoke a static method whose parameter type matches exactly the object type.

      This is a convenient wrapper for invokeExactStaticMethod(Class objectClass,String methodName,Object [] args).

      Parameters:
      objectClass - invoke static method on this class
      methodName - get method with this name
      arg - use this argument. May be null (this will result in calling the parameterless method with name methodName).
      Returns:
      The value returned by the invoked method
      Throws:
      NoSuchMethodException - if there is no such accessible method
      InvocationTargetException - wraps an exception thrown by the method invoked
      IllegalAccessException - if the requested method is not accessible via reflection
      Since:
      1.8.0

    • invokeExactStaticMethod

      public static Object invokeExactStaticMethod(Class<?> objectClass, String methodName, Object[] args) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException

      Invoke a static method whose parameter types match exactly the object types.

      This uses reflection to invoke the method obtained from a call to getAccessibleMethod(Class, String, Class[]).

      Parameters:
      objectClass - invoke static method on this class
      methodName - get method with this name
      args - use these arguments - treat null as empty array (passing null will result in calling the parameterless method with name methodName).
      Returns:
      The value returned by the invoked method
      Throws:
      NoSuchMethodException - if there is no such accessible method
      InvocationTargetException - wraps an exception thrown by the method invoked
      IllegalAccessException - if the requested method is not accessible via reflection
      Since:
      1.8.0

    • invokeExactStaticMethod

      public static Object invokeExactStaticMethod(Class<?> objectClass, String methodName, Object[] args, Class<?>[] parameterTypes) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException

      Invoke a static method whose parameter types match exactly the parameter types given.

      This uses reflection to invoke the method obtained from a call to getAccessibleMethod(Class, String, Class[]).

      Parameters:
      objectClass - invoke static method on this class
      methodName - get method with this name
      args - use these arguments - treat null as empty array (passing null will result in calling the parameterless method with name methodName).
      parameterTypes - match these parameters - treat null as empty array
      Returns:
      The value returned by the invoked method
      Throws:
      NoSuchMethodException - if there is no such accessible method
      InvocationTargetException - wraps an exception thrown by the method invoked
      IllegalAccessException - if the requested method is not accessible via reflection
      Since:
      1.8.0

    • invokeMethod

      public static Object invokeMethod(Object object, String methodName, Object arg) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException

      Invoke a named method whose parameter type matches the object type.

      The behavior of this method is less deterministic than invokeExactMethod(). It loops through all methods with names that match and then executes the first it finds with compatible parameters.

      This method supports calls to methods taking primitive parameters via passing in wrapping classes. So, for example, a Boolean class would match a boolean primitive.

      This is a convenient wrapper for invokeMethod(Object object,String methodName,Object [] args).

      Parameters:
      object - invoke method on this object
      methodName - get method with this name
      arg - use this argument. May be null (this will result in calling the parameterless method with name methodName).
      Returns:
      The value returned by the invoked method
      Throws:
      NoSuchMethodException - if there is no such accessible method
      InvocationTargetException - wraps an exception thrown by the method invoked
      IllegalAccessException - if the requested method is not accessible via reflection

    • invokeMethod

      public static Object invokeMethod(Object object, String methodName, Object[] args) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException

      Invoke a named method whose parameter type matches the object type.

      The behavior of this method is less deterministic than invokeExactMethod(Object object,String methodName,Object [] args). It loops through all methods with names that match and then executes the first it finds with compatible parameters.

      This method supports calls to methods taking primitive parameters via passing in wrapping classes. So, for example, a Boolean class would match a boolean primitive.

      This is a convenient wrapper for invokeMethod(Object object,String methodName,Object [] args,Class[] parameterTypes).

      Parameters:
      object - invoke method on this object
      methodName - get method with this name
      args - use these arguments - treat null as empty array (passing null will result in calling the parameterless method with name methodName).
      Returns:
      The value returned by the invoked method
      Throws:
      NoSuchMethodException - if there is no such accessible method
      InvocationTargetException - wraps an exception thrown by the method invoked
      IllegalAccessException - if the requested method is not accessible via reflection

    • invokeMethod

      public static Object invokeMethod(Object object, String methodName, Object[] args, Class<?>[] parameterTypes) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException

      Invoke a named method whose parameter type matches the object type.

      The behavior of this method is less deterministic than invokeExactMethod(Object object,String methodName,Object [] args,Class[] parameterTypes). It loops through all methods with names that match and then executes the first it finds with compatible parameters.

      This method supports calls to methods taking primitive parameters via passing in wrapping classes. So, for example, a Boolean class would match a boolean primitive.

      Parameters:
      object - invoke method on this object
      methodName - get method with this name
      args - use these arguments - treat null as empty array (passing null will result in calling the parameterless method with name methodName).
      parameterTypes - match these parameters - treat null as empty array
      Returns:
      The value returned by the invoked method
      Throws:
      NoSuchMethodException - if there is no such accessible method
      InvocationTargetException - wraps an exception thrown by the method invoked
      IllegalAccessException - if the requested method is not accessible via reflection

    • invokeStaticMethod

      public static Object invokeStaticMethod(Class<?> objectClass, String methodName, Object arg) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException

      Invoke a named static method whose parameter type matches the object type.

      The behavior of this method is less deterministic than invokeExactMethod(Object, String, Object[], Class[]). It loops through all methods with names that match and then executes the first it finds with compatible parameters.

      This method supports calls to methods taking primitive parameters via passing in wrapping classes. So, for example, a Boolean class would match a boolean primitive.

      This is a convenient wrapper for invokeStaticMethod(Class objectClass,String methodName,Object [] args).

      Parameters:
      objectClass - invoke static method on this class
      methodName - get method with this name
      arg - use this argument. May be null (this will result in calling the parameterless method with name methodName).
      Returns:
      The value returned by the invoked method
      Throws:
      NoSuchMethodException - if there is no such accessible method
      InvocationTargetException - wraps an exception thrown by the method invoked
      IllegalAccessException - if the requested method is not accessible via reflection
      Since:
      1.8.0

    • invokeStaticMethod

      public static Object invokeStaticMethod(Class<?> objectClass, String methodName, Object[] args) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException

      Invoke a named static method whose parameter type matches the object type.

      The behavior of this method is less deterministic than invokeExactMethod(Object object,String methodName,Object [] args). It loops through all methods with names that match and then executes the first it finds with compatible parameters.

      This method supports calls to methods taking primitive parameters via passing in wrapping classes. So, for example, a Boolean class would match a boolean primitive.

      This is a convenient wrapper for invokeStaticMethod(Class objectClass,String methodName,Object [] args,Class[] parameterTypes).

      Parameters:
      objectClass - invoke static method on this class
      methodName - get method with this name
      args - use these arguments - treat null as empty array (passing null will result in calling the parameterless method with name methodName).
      Returns:
      The value returned by the invoked method
      Throws:
      NoSuchMethodException - if there is no such accessible method
      InvocationTargetException - wraps an exception thrown by the method invoked
      IllegalAccessException - if the requested method is not accessible via reflection
      Since:
      1.8.0

    • invokeStaticMethod

      public static Object invokeStaticMethod(Class<?> objectClass, String methodName, Object[] args, Class<?>[] parameterTypes) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException

      Invoke a named static method whose parameter type matches the object type.

      The behavior of this method is less deterministic than invokeExactStaticMethod(Class objectClass,String methodName,Object [] args,Class[] parameterTypes). It loops through all methods with names that match and then executes the first it finds with compatible parameters.

      This method supports calls to methods taking primitive parameters via passing in wrapping classes. So, for example, a Boolean class would match a boolean primitive.

      Parameters:
      objectClass - invoke static method on this class
      methodName - get method with this name
      args - use these arguments - treat null as empty array (passing null will result in calling the parameterless method with name methodName).
      parameterTypes - match these parameters - treat null as empty array
      Returns:
      The value returned by the invoked method
      Throws:
      NoSuchMethodException - if there is no such accessible method
      InvocationTargetException - wraps an exception thrown by the method invoked
      IllegalAccessException - if the requested method is not accessible via reflection
      Since:
      1.8.0

    • isAssignmentCompatible

      public static final boolean isAssignmentCompatible(Class<?> parameterType, Class<?> parameterization)

      Determine whether a type can be used as a parameter in a method invocation. This method handles primitive conversions correctly.

      In order words, it will match a Boolean to a boolean, a Long to a long, a Float to a float, a Integer to a int, and a Double to a double. Now logic widening matches are allowed. For example, a Long will not match a int.

      Parameters:
      parameterType - the type of parameter accepted by the method
      parameterization - the type of parameter being tested
      Returns:
      true if the assignment is compatible.

    • setCacheMethods

      public static void setCacheMethods(boolean cacheMethods)
      Set whether methods should be cached for greater performance or not, default is true.
      Parameters:
      cacheMethods - true if methods should be cached for greater performance, otherwise false
      Since:
      1.8.0

    • setMethodAccessible

      private static void setMethodAccessible(Method method)
      Try to make the method accessible
      Parameters:
      method - The source arguments

    • toArray

      private static Object[] toArray(Object arg)

    • toNonPrimitiveClass

      public static Class<?> toNonPrimitiveClass(Class<?> clazz)
      Find a non primitive representation for given primitive class.
      Parameters:
      clazz - the class to find a representation for, not null
      Returns:
      the original class if it not a primitive. Otherwise the wrapper class. Not null