com.ovea.tajin.server.util.DeleteOnExitHook Maven / Gradle / Ivy

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/**
 * Copyright (C) 2011 Ovea 
 *
 * 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.ovea.tajin.server.util;

import java.io.File;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashSet;

final class DeleteOnExitHook implements Runnable {
    private static final DeleteOnExitHook instance = new DeleteOnExitHook();
    private LinkedHashSet files = new LinkedHashSet();

    private DeleteOnExitHook() {
        Runtime.getRuntime().addShutdownHook(new Thread(this, "DeleteOnExitHookThread"));
    }

    public void run() {
        LinkedHashSet theFiles;
        synchronized (files) {
            theFiles = files;
            files = null;
        }
        ArrayList toBeDeleted = new ArrayList(theFiles);
        // Reverse the list to maintain previous jdk deletion order.
        // Last in first deleted.
        Collections.reverse(toBeDeleted);
        for (File file : toBeDeleted) {
            deleteSubFolders(file);
            file.delete();
        }
    }

    public void deleteSubFolders(File file) {
        File[] files = file.listFiles();
        for (File f : files) {
            if (f.isDirectory()) {
                deleteSubFolders(f);
            }
            f.delete();
        }
    }

    public DeleteOnExitHook add(File file) {
        synchronized (files) {
            if (files == null) {
                throw new IllegalStateException("Shutdown in progress");
            }
            files.add(file);
        }
        return this;
    }

    public static DeleteOnExitHook instance() {
        return instance;
    }
}