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package sun.swing;
import java.security.*;
import java.lang.reflect.*;
A utility for accessing and invoking methods, via reflection,
that would otherwise be unaccessible.
Author: Shannon Hickey
/**
* A utility for accessing and invoking methods, via reflection,
* that would otherwise be unaccessible.
*
* @author Shannon Hickey
*/
public class AccessibleMethod {
private final Method method;
Construct an instance for the given params.
Params: - klass – the class to which the method belongs
- methodName – the name of the method
- paramTypes – the paramater type array
Throws: - NullPointerException – if
klass
or name is null - NoSuchMethodException – if the method can't be found
/**
* Construct an instance for the given params.
*
* @param klass the class to which the method belongs
* @param methodName the name of the method
* @param paramTypes the paramater type array
* @throws NullPointerException if <code>klass</code>
* or <code>name</code> is <code>null</code>
* @throws NoSuchMethodException if the method can't be found
*/
public AccessibleMethod(Class klass,
String methodName,
Class ... paramTypes) throws NoSuchMethodException {
try {
method = AccessController.doPrivileged(
new AccessMethodAction(klass, methodName, paramTypes));
} catch (PrivilegedActionException e) {
throw (NoSuchMethodException)e.getCause();
}
}
Invoke the method that this object represents.
Has the same behavior and throws the same exceptions as
java.lang.reflect.Method.invoke with one
exception: This method does not throw
IllegalAccessException since the target
method has already been made accessible.
Params: - obj – the object the underlying method is invoked from
- args – the arguments used for the method call
See Also: Returns: the result of dispatching the method represented by
this object on obj with parameters
args
/**
* Invoke the method that this object represents.
* Has the same behavior and throws the same exceptions as
* <code>java.lang.reflect.Method.invoke</code> with one
* exception: This method does not throw
* <code>IllegalAccessException</code> since the target
* method has already been made accessible.
*
* @param obj the object the underlying method is invoked from
* @param args the arguments used for the method call
* @return the result of dispatching the method represented by
* this object on <code>obj</code> with parameters
* <code>args</code>
* @see java.lang.reflect.Method#invoke
*/
public Object invoke(Object obj, Object ... args)
throws IllegalArgumentException, InvocationTargetException {
try {
return method.invoke(obj, args);
} catch (IllegalAccessException e) {
// should never happen since we've made it accessible
throw new AssertionError("accessible method inaccessible");
}
}
Invoke the method that this object represents, with the
expectation that the method being called throws no
checked exceptions.
Simply calls this.invoke(obj, args)
but catches any InvocationTargetException
and returns the cause wrapped in a runtime exception.
Params: - obj – the object the underlying method is invoked from
- args – the arguments used for the method call
See Also: Returns: the result of dispatching the method represented by
this object on obj with parameters
args
/**
* Invoke the method that this object represents, with the
* expectation that the method being called throws no
* checked exceptions.
* <p>
* Simply calls <code>this.invoke(obj, args)</code>
* but catches any <code>InvocationTargetException</code>
* and returns the cause wrapped in a runtime exception.
*
* @param obj the object the underlying method is invoked from
* @param args the arguments used for the method call
* @return the result of dispatching the method represented by
* this object on <code>obj</code> with parameters
* <code>args</code>
* @see #invoke
*/
public Object invokeNoChecked(Object obj, Object ... args) {
try {
return invoke(obj, args);
} catch (InvocationTargetException ex) {
if (ex.getCause() instanceof RuntimeException) {
throw (RuntimeException)ex.getCause();
} else {
throw new RuntimeException(ex.getCause());
}
}
}
The action used to fetch the method and make it accessible /** The action used to fetch the method and make it accessible */
private static class AccessMethodAction implements PrivilegedExceptionAction<Method> {
private final Class<?> klass;
private final String methodName;
private final Class[] paramTypes;
public AccessMethodAction(Class klass,
String methodName,
Class ... paramTypes) {
this.klass = klass;
this.methodName = methodName;
this.paramTypes = paramTypes;
}
public Method run() throws NoSuchMethodException {
Method method = klass.getDeclaredMethod(methodName, paramTypes);
method.setAccessible(true);
return method;
}
}
}