org.algorithmx.rules.util.ReflectionUtils Maven / Gradle / Ivy
/**
* This software is licensed under the Apache 2 license, quoted below.
*
* Copyright (c) 1999-2019, Live Software & Consultants Inc ([email protected])
*
* 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.algorithmx.rules.util;
import org.algorithmx.rules.spring.core.DefaultParameterNameDiscoverer;
import org.algorithmx.rules.spring.core.ParameterNameDiscoverer;
import org.algorithmx.rules.spring.util.Assert;
import javax.annotation.PostConstruct;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
/**
* Reflection related utility methods.
*
* @author Max Arulananthan
* @since 1.0
*/
public final class ReflectionUtils {
private static final ParameterNameDiscoverer parameterNameDiscoverer = new DefaultParameterNameDiscoverer();
private ReflectionUtils() {
super();
}
/**
* Retrieves the method parameter names. First it looks for @Param to get the parameter information.
* If that failed then we use standard Java Reflection techniques to retrieve the information and If that fails
* we use ASM to load the bytecode to find the method information.
*
* @param method target method
* @return method parameter names.
*/
public static String[] getParameterNames(Method method) {
return parameterNameDiscoverer.getParameterNames(method);
}
/**
* Finds the PostConstruct method(s) in a given class.
*
* @param c desired class
* @return PostConstruct methods (if found); null otherwise.
*/
public static List getPostConstructMethods(Class c) {
return Arrays.stream(c.getDeclaredMethods())
.filter(method -> void.class.equals(method.getReturnType()) &&
method.getParameterCount() == 0 && method.getExceptionTypes().length == 0 &&
method.getAnnotation(PostConstruct.class) != null).collect(Collectors.toList());
}
/**
* Invokes the PostConstruct method on the given target.
*
* @param postConstructMethod post constructor method.
* @param target target object.
*/
public static void invokePostConstruct(Method postConstructMethod, Object target) {
Assert.notNull(postConstructMethod, "postConstructMethod cannot be null");
postConstructMethod.setAccessible(true);
try {
postConstructMethod.invoke(target);
} catch (IllegalAccessException e) {
throw new IllegalArgumentException("Error occurred trying to call @PostConstruct ["
+ postConstructMethod + "]", e);
} catch (InvocationTargetException e) {
throw new IllegalArgumentException("Error occurred trying to call @PostConstruct ["
+ postConstructMethod + "]", e);
}
}
}