co.cask.cdap.common.lang.ProgramClassLoader.java Source code

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Here is the source code for co.cask.cdap.common.lang.ProgramClassLoader.java

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/*
 * Copyright  2014 Cask Data, Inc.
 *
 * 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 co.cask.cdap.common.lang;

import co.cask.cdap.proto.ProgramType;
import com.google.common.base.Predicates;
import com.google.common.collect.ImmutableSet;

import java.io.File;
import java.io.IOException;
import java.util.Set;
import javax.annotation.Nullable;

/**
 * ClassLoader that implements bundle jar feature, in which the application jar contains
 * its dependency jars inside.
 */
public class ProgramClassLoader extends DirectoryClassLoader {

    /**
     * Constructs an instance that load classes from the given directory, without program type. See
     * {@link ProgramResources#getVisibleResources(ProgramType)} for details on system classes that
     * are visible to the returned ClassLoader.
     */
    public static ProgramClassLoader create(File unpackedJarDir, ClassLoader parentClassLoader) throws IOException {
        return create(unpackedJarDir, parentClassLoader, null);
    }

    /**
     * Constructs an instance that load classes from the given directory for the given program type.
     * <p/>
     * The URLs for class loading are:
     * <p/>
     * <pre>
     * [dir]
     * [dir]/*.jar
     * [dir]/lib/*.jar
     * </pre>
     */
    public static ProgramClassLoader create(File unpackedJarDir, ClassLoader parentClassLoader,
            @Nullable ProgramType programType) throws IOException {
        Set<String> visibleResources = ProgramResources.getVisibleResources(programType);
        ImmutableSet.Builder<String> visiblePackages = ImmutableSet.builder();
        for (String resource : visibleResources) {
            if (resource.endsWith(".class")) {
                int idx = resource.lastIndexOf('/');
                // Ignore empty package
                if (idx > 0) {
                    visiblePackages.add(resource.substring(0, idx));
                }
            }
        }

        ClassLoader filteredParent = new FilterClassLoader(Predicates.in(visibleResources),
                Predicates.in(visiblePackages.build()), parentClassLoader);
        return new ProgramClassLoader(unpackedJarDir, filteredParent);
    }

    private ProgramClassLoader(File dir, ClassLoader parent) {
        super(dir, parent, "lib");
    }
}