org.springframework.boot.loader.ExecutableArchiveLauncher.java Source code

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Here is the source code for org.springframework.boot.loader.ExecutableArchiveLauncher.java

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/*
 * Copyright 2012-2019 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.boot.loader;

import java.util.ArrayList;
import java.util.List;
import java.util.jar.JarEntry;
import java.util.jar.Manifest;

import org.springframework.boot.loader.archive.Archive;

/**
 * Base class for executable archive {@link Launcher}s.
 *
 * @author Phillip Webb
 * @author Andy Wilkinson
 * @since 1.0.0
 */
public abstract class ExecutableArchiveLauncher extends Launcher {

    private final Archive archive;

    public ExecutableArchiveLauncher() {
        try {
            this.archive = createArchive();
        } catch (Exception ex) {
            throw new IllegalStateException(ex);
        }
    }

    protected ExecutableArchiveLauncher(Archive archive) {
        this.archive = archive;
    }

    protected final Archive getArchive() {
        return this.archive;
    }

    @Override
    protected String getMainClass() throws Exception {
        Manifest manifest = this.archive.getManifest();
        String mainClass = null;
        if (manifest != null) {
            mainClass = manifest.getMainAttributes().getValue("Start-Class");
        }
        if (mainClass == null) {
            throw new IllegalStateException("No 'Start-Class' manifest entry specified in " + this);
        }
        return mainClass;
    }

    @Override
    protected List<Archive> getClassPathArchives() throws Exception {
        List<Archive> archives = new ArrayList<>(this.archive.getNestedArchives(this::isNestedArchive));
        postProcessClassPathArchives(archives);
        return archives;
    }

    /**
     * Determine if the specified {@link JarEntry} is a nested item that should be added
     * to the classpath. The method is called once for each entry.
     * @param entry the jar entry
     * @return {@code true} if the entry is a nested item (jar or folder)
     */
    protected abstract boolean isNestedArchive(Archive.Entry entry);

    /**
     * Called to post-process archive entries before they are used. Implementations can
     * add and remove entries.
     * @param archives the archives
     * @throws Exception if the post processing fails
     */
    protected void postProcessClassPathArchives(List<Archive> archives) throws Exception {
    }

}