org.gridgain.grid.spi.deployment.uri.GridUriDeploymentClassLoader Maven / Gradle / Ivy

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/* 
 Copyright (C) GridGain Systems. All Rights Reserved.
 
 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.gridgain.grid.spi.deployment.uri;

import org.gridgain.grid.util.typedef.internal.*;
import org.jetbrains.annotations.*;

import java.io.*;
import java.net.*;
import java.util.*;

/**
 * Loads classes and resources from "unpacked" GAR file (GAR directory).
 * 
 * Class loader scans GAR directory first and then if
 * class/resource was not found scans all JAR files.
 */
class GridUriDeploymentClassLoader extends URLClassLoader {
    /**
     * Creates new instance of class loader.
     *
     * @param urls The URLs from which to load classes and resources.
     * @param parent The parent class loader for delegation.
     */
    GridUriDeploymentClassLoader(URL[] urls, ClassLoader parent) {
        super(urls, parent);
    }

    /** {@inheritDoc} */
    @Override protected synchronized Class loadClass(String name, boolean resolve) throws ClassNotFoundException {
        // First, check if the class has already been loaded.
        Class cls = findLoadedClass(name);

        if (cls == null) {
            try {
                try {
                    // Search classes in GAR file.
                    // NOTE: findClass(String) is not overridden since it is always called after
                    // findLoadedClass(String) in exclusive synchronization block.
                    cls = findClass(name);
                }
                catch (ClassNotFoundException ignored) {
                    // If still not found, then invoke parent class loader in order
                    // to find the class.
                    cls = super.loadClass(name, resolve);
                }
            }
            catch (ClassNotFoundException e) {
                throw e;
            }
            // Catch Throwable to secure against any errors resulted from
            // corrupted class definitions or other user errors.
            catch (Exception e) {
                throw new ClassNotFoundException("Failed to load class due to unexpected error: " + name, e);
            }
        }

        return cls;
    }

    /**
     * Load class from GAR file.
     *
     * @param name Class name.
     * @return Loaded class.
     * @throws ClassNotFoundException If no class found.
     */
    public synchronized Class loadClassGarOnly(String name) throws ClassNotFoundException {
        // First, check if the class has already been loaded.
        Class cls = findLoadedClass(name);

        if (cls == null) {
            try {
                // Search classes in GAR file.
                // NOTE: findClass(String) is not overridden since it is always called after
                // findLoadedClass(String) in exclusive synchronization block.
                cls = findClass(name);
            }
            catch (ClassNotFoundException e) {
                throw e;
            }
            // Catch Throwable to secure against any errors resulted from
            // corrupted class definitions or other user errors.
            catch (Exception e) {
                throw new ClassNotFoundException("Failed to load class due to unexpected error: " + name, e);
            }
        }

        return cls;
    }

    /** {@inheritDoc} */
    @Override public URL getResource(String name) {
        URL url = findResource(name);

        if (url == null)
            url = ClassLoader.getSystemResource(name);

        if (url == null)
            url = super.getResource(name);

        return url;
    }

    /** {@inheritDoc} */
    @Override public InputStream getResourceAsStream(String name) {
        // Find resource in GAR file first.
        InputStream in = getResourceAsStreamGarOnly(name);

        // Find resource in parent class loader.
        if (in == null)
            in = ClassLoader.getSystemResourceAsStream(name);

        if (in == null)
            in = super.getResourceAsStream(name);

        return in;
    }

    /**
     * Returns an input stream for reading the specified resource from GAR file only.
     *
     * @param name Resource name.
     * @return An input stream for reading the resource, or {@code null}
     *      if the resource could not be found.
     */
    @Nullable public InputStream getResourceAsStreamGarOnly(String name) {
        URL url = findResource(name);

        try {
            return url != null ? url.openStream() : null;
        }
        catch (IOException ignored) {
            return null;
        }
    }

    /** {@inheritDoc} */
    @Override public String toString() {
        return S.toString(GridUriDeploymentClassLoader.class, this, "urls", Arrays.toString(getURLs()));
    }
}