DynamicExecutor.java

/*
 * Copyright (C)  Tony Green, Litepal Framework Open Source Project
 *
 * 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 org.litepal.crud;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import org.litepal.exceptions.DataSupportException;

/**
 * This provides a send method to allow calling method in dynamic way. (Just
 * like Ruby, but not clean or easy as Ruby to use).
 * 
 * @author Tony Green
 * @since 1.1
 */
class DynamicExecutor {

	/**
	 * Disable to create an instance of DynamicExecutor.
	 */
	private DynamicExecutor() {
	}

	/**
	 * This method use java reflect API to execute method dynamically. Most
	 * importantly, it could access the methods with private modifier to break
	 * encapsulation.
	 * 
	 * @param object
	 *            The object to invoke method.
	 * @param methodName
	 *            The method name to invoke.
	 * @param parameters
	 *            The parameters.
	 * @param objectClass
	 *            Use objectClass to find method to invoke.
	 * @param parameterTypes
	 *            The parameter types.
	 * @return Returns the result of dynamically invoking method.
	 * @throws SecurityException
	 * @throws IllegalArgumentException
	 * @throws IllegalAccessException
	 * @throws InvocationTargetException
	 */
	static Object send(Object object, String methodName, Object[] parameters, Class<?> objectClass,
			Class<?>[] parameterTypes) throws SecurityException, IllegalArgumentException,
			IllegalAccessException, InvocationTargetException {
		try {
			if (parameters == null) {
				parameters = new Object[] {};
			}
			if (parameterTypes == null) {
				parameterTypes = new Class[] {};
			}
			Method method = objectClass.getDeclaredMethod(methodName, parameterTypes);
			method.setAccessible(true);
			return method.invoke(object, parameters);
		} catch (NoSuchMethodException e) {
			throw new DataSupportException(DataSupportException.noSuchMethodException(
					objectClass.getSimpleName(), methodName));
		}
	}

	/**
	 * This method use java reflect API to set field value dynamically. Most
	 * importantly, it could access fields with private modifier to break
	 * encapsulation.
	 * 
	 * @param object
	 *            The object to access.
	 * @param fieldName
	 *            The field name to access.
	 * @param value
	 *            Assign this value to field.
	 * @param objectClass
	 *            The class of object.
	 * @throws SecurityException
	 * @throws IllegalArgumentException
	 * @throws IllegalAccessException
	 */
	static void setField(Object object, String fieldName, Object value, Class<?> objectClass)
			throws SecurityException, IllegalArgumentException, IllegalAccessException {
		try {
			Field objectField = objectClass.getDeclaredField(fieldName);
			objectField.setAccessible(true);
			objectField.set(object, value);
		} catch (NoSuchFieldException e) {
			throw new DataSupportException(DataSupportException.noSuchFieldExceptioin(
					objectClass.getSimpleName(), fieldName));
		}
	}

	/**
	 * This method use java reflect API to get field value dynamically. Most
	 * importantly, it could access fields with private modifier to break
	 * encapsulation.
	 * 
	 * @param object
	 *            The object to access.
	 * @param fieldName
	 *            The field name to access.
	 * @param objectClass
	 *            The class of object.
	 * @throws SecurityException
	 * @throws NoSuchFieldException
	 * @throws IllegalArgumentException
	 * @throws IllegalAccessException
	 */
	static Object getField(Object object, String fieldName, Class<?> objectClass)
			throws IllegalArgumentException, IllegalAccessException {
		try {
			Field objectField = objectClass.getDeclaredField(fieldName);
			objectField.setAccessible(true);
			return objectField.get(object);
		} catch (NoSuchFieldException e) {
			throw new DataSupportException(DataSupportException.noSuchFieldExceptioin(
					objectClass.getSimpleName(), fieldName));
		}
	}

}