/** * PermissionsEx * Copyright (C) zml and PermissionsEx contributors * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package ninja.leaping.permissionsex.bukkit; import java.lang.reflect.Field; /** * @author zml2008 */ public class FieldReplacer<Instance, Type> { private final Class<Type> requiredType; private final Field field; public FieldReplacer(Class<? extends Instance> clazz, String fieldName, Class<Type> requiredType) { this.requiredType = requiredType; field = getField(clazz, fieldName); if (field == null) { throw new ExceptionInInitializerError("No such field " + fieldName + " in class " + clazz); } field.setAccessible(true); if (!requiredType.isAssignableFrom(field.getType())) { throw new ExceptionInInitializerError("Field of wrong type"); } } public Type get(Instance instance) { try { return this.requiredType.cast(field.get(instance)); } catch (IllegalAccessException e) { throw new Error(e); } } public void set(Instance instance, Type newValue) { try { field.set(instance, newValue); } catch (IllegalAccessException e) { throw new Error(e); // This shouldn't happen because we call setAccessible in the constructor } } private static Field getField(Class<?> clazz, String fieldName) { while (clazz != null && clazz != Object.class) { try { return clazz.getDeclaredField(fieldName); } catch (NoSuchFieldException e) { clazz = clazz.getSuperclass(); } } return null; } }