Extracts a method matching the source method, allowing generic type parameters to be substituted as long as they are properly castable. - Java Reflection

Java examples for Reflection:Method Parameter

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Description

Extracts a method matching the source method, allowing generic type parameters to be substituted as long as they are properly castable.

Demo Code

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 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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.
 */
import java.lang.reflect.Method;
import javax.enterprise.inject.Typed;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.jar.Manifest;
import java.util.jar.Attributes;
import java.net.URL;

public class Main{
    /**
     * Extracts a method matching the source method, allowing generic type parameters to be substituted as
     * long as they are properly castable.
     *
     * @param clazz The target class
     * @param sourceMethod The source method.
     * @return the extracted method or <code>null</code>
     */
    public static Method extractPossiblyGenericMethod(Class<?> clazz,
            Method sourceMethod) {
        Method exactMethod = extractMethod(clazz, sourceMethod);
        if (exactMethod == null) {
            String methodName = sourceMethod.getName();
            Class<?>[] parameterTypes = sourceMethod.getParameterTypes();
            for (Method method : clazz.getMethods()) {
                if (method.getName().equals(methodName)
                        && allSameType(method.getParameterTypes(),
                                parameterTypes)) {
                    return method;
                }
            }
            return null;
        } else {
            return exactMethod;
        }
    }
    /**
     * Extracts a method with same signature as the source method.
     * 
     * @param clazz The target class
     * @param sourceMethod The source method.
     * @return the extracted method or <code>null</code>
     */
    public static Method extractMethod(Class<?> clazz, Method sourceMethod) {
        try {
            String name = sourceMethod.getName();
            return clazz != null ? clazz.getMethod(name,
                    sourceMethod.getParameterTypes()) : null;
        } catch (NoSuchMethodException e) {
            return null;
        }
    }
    /**
     * Whether all of the parameters from left to right are equivalent.
     * In order to support generics, it takes the form of left.isAssignableFrom(right)
     * @param left left hand side to check
     * @param right right hand side to check
     * @return whether all of the left classes can be assigned to the right hand side types
     */
    private static boolean allSameType(Class<?>[] left, Class<?>[] right) {
        if (left.length != right.length) {
            return false;
        }
        for (int p = 0; p < left.length; p++) {
            if (!left[p].isAssignableFrom(right[p])) {
                return false;
            }
        }
        return true;
    }
}

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