ProxyClass.java

package com.github.gquintana.metrics.proxy;

/*
 * #%L
 * Metrics SQL
 * %%
 * Copyright (C) 2014 Open-Source
 * %%
 * 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.
 * #L%
 */

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;
import java.util.Arrays;
import java.util.Objects;

/**
 * Proxy class key
 */
public final class ProxyClass {
    private final ClassLoader classLoader;
    private final Class<?>[] interfaces;
    private final int hashCode;

    public ProxyClass(ClassLoader classLoader, Class<?>... interfaces) {
        this.classLoader = classLoader;
        this.interfaces = interfaces;
        // Generate hascode once for all
        final Object[] hashValue = new Object[interfaces.length + 1];
        hashValue[0] = classLoader;
        System.arraycopy(interfaces, 0, hashValue, 1, interfaces.length);
        this.hashCode = Objects.hash(hashValue);
    } // Generate hascode once for all

    public ClassLoader getClassLoader() {
        return classLoader;
    }

    public Class<?>[] getInterfaces() {
        return interfaces;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        final ProxyClass that = (ProxyClass) o;
        return (this.hashCode == that.hashCode) && Objects.equals(this.classLoader, that.classLoader) && Arrays.equals(this.interfaces, that.interfaces);
    }

    @Override
    public int hashCode() {
        return hashCode;
    }
    /**
     * Create proxy class
     */
    public Class createClass() {
        return Proxy.getProxyClass(getClassLoader(), getInterfaces());
    }
    /**
     * Create proxy constructor
     */
    public Constructor createConstructor() {
        try {
            return createClass().getConstructor(InvocationHandler.class);
        } catch (NoSuchMethodException noSuchMethodException) {
            throw new ProxyException(noSuchMethodException);
        }
    }
}