ReflectionUtils.java

/*
 * Copyright (C) 2015 SoftIndex LLC.
 *
 * 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 io.datakernel.jmx;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

import static io.datakernel.util.Preconditions.checkArgument;

final class ReflectionUtils {

	private ReflectionUtils() {}

	public static boolean isJmxStats(Class<?> clazz) {
		return JmxStats.class.isAssignableFrom(clazz);
	}

	public static boolean isJmxRefreshableStats(Class<?> clazz) {
		return JmxRefreshableStats.class.isAssignableFrom(clazz);
	}

	public static boolean isPrimitiveType(Class<?> clazz) {
		return boolean.class.isAssignableFrom(clazz)
				|| byte.class.isAssignableFrom(clazz)
				|| short.class.isAssignableFrom(clazz)
				|| char.class.isAssignableFrom(clazz)
				|| int.class.isAssignableFrom(clazz)
				|| long.class.isAssignableFrom(clazz)
				|| float.class.isAssignableFrom(clazz)
				|| double.class.isAssignableFrom(clazz);
	}

	public static boolean isPrimitiveTypeWrapper(Class<?> clazz) {
		return Boolean.class.isAssignableFrom(clazz)
				|| Byte.class.isAssignableFrom(clazz)
				|| Short.class.isAssignableFrom(clazz)
				|| Character.class.isAssignableFrom(clazz)
				|| Integer.class.isAssignableFrom(clazz)
				|| Long.class.isAssignableFrom(clazz)
				|| Float.class.isAssignableFrom(clazz)
				|| Double.class.isAssignableFrom(clazz);
	}

	public static boolean isString(Class<?> clazz) {
		return String.class.isAssignableFrom(clazz);
	}

	public static boolean isThrowable(Class<?> clazz) {
		return Throwable.class.isAssignableFrom(clazz);
	}

	public static boolean isGetter(Method method) {
		boolean returnsBoolean = method.getReturnType() == boolean.class || method.getReturnType() == Boolean.class;
		boolean isIsGetter = method.getName().length() > 2 && method.getName().startsWith("is") && returnsBoolean;

		boolean doesntReturnVoid = method.getReturnType() != void.class;
		boolean isGetGetter = method.getName().length() >= 3 && method.getName().startsWith("get") && doesntReturnVoid;

		return isIsGetter || isGetGetter;
	}

	public static String extractFieldNameFromGetter(Method getter) {
		checkArgument(isGetter(getter));

		if (getter.getName().startsWith("get")) {
			if (getter.getName().length() == 3) {
				return "";
			} else {
				String getterName = getter.getName();
				String firstLetter = getterName.substring(3, 4);
				String restOfName = getterName.substring(4);
				return firstLetter.toLowerCase() + restOfName;
			}
		} else if (getter.getName().startsWith("is")) {
			String getterName = getter.getName();
			String firstLetter = getterName.substring(2, 3);
			String restOfName = getterName.substring(3);
			return firstLetter.toLowerCase() + restOfName;
		} else {
			throw new RuntimeException();
		}
	}

	public static boolean isSetter(Method method) {
		boolean hasSingleParameter = method.getParameterTypes().length == 1;
		return method.getName().length() > 3 && method.getName().startsWith("set")
				&& method.getReturnType() == void.class && hasSingleParameter;
	}

	public static String extractFieldNameFromSetter(Method setter) {
		checkArgument(isSetter(setter));

		String setterName = setter.getName();
		String firstLetter = setterName.substring(3, 4);
		String restOfName = setterName.substring(4);
		return firstLetter.toLowerCase() + restOfName;
	}

	public static boolean classHasPublicNoArgConstructor(Class<?> clazz) {
		for (Constructor<?> constructor : clazz.getConstructors()) {
			if (constructor.getParameterTypes().length == 0) {
				return true;
			}
		}
		return false;
	}

	public static boolean classHasPublicStaticFactoryMethod(Class<?> clazz, String methodName) {
		Method createMethod;
		try {
			createMethod = clazz.getDeclaredMethod(methodName);
		} catch (NoSuchMethodException e) {
			return false;
		}

		return Modifier.isStatic(createMethod.getModifiers()) &&
				Modifier.isPublic(createMethod.getModifiers()) &&
				createMethod.getReturnType().equals(clazz);
	}
}