private static <T> T getFieldInternal(Object instance, Class<?> fieldOwner, String fieldname) {
Field target;
try {
target = fieldOwner.getDeclaredField(fieldname);
} catch (NoSuchFieldException e) {
throw Exceptions.newIllegalArgumentException("%s has no field named %s", instance, fieldname);
}
boolean alreadyAccessible = target.isAccessible();
if (!alreadyAccessible) {
target.setAccessible(true);
}
try {
@SuppressWarnings("unchecked") // we've already left statically-typed land,
// so we may as well make it convenient for callers
T value = (T) target.get(instance);
return value;
} catch (IllegalAccessException e) {
throw Throwables.propagate(e);
} finally {
if (!alreadyAccessible) {
target.setAccessible(false);
}
}
}
public static <T> InvocationTarget<T> invokeSpecificMethod(
Object instance, Class<?> methodOwner, String methodName, Class<?>... argTypes) {
Preconditions.checkArgument(
methodOwner.isInstance(instance), "%s is not a %s", instance, methodOwner);
Method target;
try {
target = methodOwner.getDeclaredMethod(methodName, argTypes);
} catch (NoSuchMethodException e) {
throw Exceptions.newIllegalArgumentException(
"%s has no method named %s and with argument types %s",
instance.getClass(), methodName, Arrays.toString(argTypes));
}
return new InvocationTarget<T>(target, instance);
}
/**
* Uses reflection to set a (potentially private) non-static field to the given value.
*
* @param instance the object instance whose private field should be changed
* @param fieldOwner the class that declares the target field
* @param fieldname the name of the target field
* @param value the new value
*/
public static void setField(
Object instance, Class<?> fieldOwner, String fieldname, Object value) {
Preconditions.checkArgument(
fieldOwner.isInstance(instance), "%s is not a %s", instance, fieldOwner);
Field target;
try {
target = fieldOwner.getDeclaredField(fieldname);
} catch (NoSuchFieldException e) {
throw Exceptions.newIllegalArgumentException("%s has no field named %s", instance, fieldname);
}
boolean alreadyAccessible = target.isAccessible();
if (!alreadyAccessible) {
target.setAccessible(true);
}
try {
target.set(instance, value);
} catch (IllegalAccessException e) {
throw Throwables.propagate(e);
} finally {
if (!alreadyAccessible) {
target.setAccessible(false);
}
}
}
