com.haulmont.cuba.core.config.ConfigDefaultMethod.java Source code

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Here is the source code for com.haulmont.cuba.core.config.ConfigDefaultMethod.java

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/*
 * Copyright (c) 2008-2018 Haulmont.
 *
 * 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 com.haulmont.cuba.core.config;

import org.apache.commons.lang3.SystemUtils;

import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

/**
 * Invokes default method of configuration interfaces.
 */
public class ConfigDefaultMethod extends ConfigMethod {

    private final Class<?> configInterface;
    private final Method configMethod;

    public ConfigDefaultMethod(Class<?> configInterface, Method configMethod) {
        this.configInterface = configInterface;
        this.configMethod = configMethod;
    }

    @Override
    public Object invoke(ConfigHandler handler, Object[] args, Object proxy) {
        try {
            if (SystemUtils.IS_JAVA_1_8) {
                // hack to invoke default method of an interface reflectively
                Constructor<MethodHandles.Lookup> lookupConstructor = MethodHandles.Lookup.class
                        .getDeclaredConstructor(Class.class, Integer.TYPE);
                if (!lookupConstructor.isAccessible()) {
                    lookupConstructor.setAccessible(true);
                }
                return lookupConstructor.newInstance(configInterface, MethodHandles.Lookup.PRIVATE)
                        .unreflectSpecial(configMethod, configInterface).bindTo(proxy).invokeWithArguments(args);
            } else {
                return MethodHandles.lookup()
                        .findSpecial(configInterface, configMethod.getName(),
                                MethodType.methodType(configMethod.getReturnType(),
                                        configMethod.getParameterTypes()),
                                configInterface)
                        .bindTo(proxy).invokeWithArguments(args);
            }
        } catch (Throwable throwable) {
            throw new RuntimeException("Error invoking default method of config interface", throwable);
        }
    }

    /**
     * The ConfigDefaultMethod factory.
     */
    public static final Factory FACTORY = new Factory() {

        /**
         * The method is default and has a non-void return type.
         */
        @Override
        public boolean canHandle(Method method) {
            return method.isDefault() && !Void.TYPE.equals(method.getReturnType());
        }

        @Override
        public ConfigMethod newInstance(Class<?> configInterface, Method configMethod) {
            return new ConfigDefaultMethod(configInterface, configMethod);
        }
    };
}