DeleteFileTasklet.java

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2015 Almex
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

package be.raildelays.batch.tasklet;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.batch.core.StepContribution;
import org.springframework.batch.core.scope.context.ChunkContext;
import org.springframework.batch.core.step.tasklet.Tasklet;
import org.springframework.batch.repeat.RepeatStatus;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.core.io.Resource;
import org.springframework.util.Assert;

import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.stream.Stream;

/**
 * Delete all files contained in the array of resources.
 * Try first to delete via {@link File#delete()} and then fallback to {@link File#deleteOnExit()} if it did not succeed.
 *
 * @author Almex
 * @since 1.2
 */
public class DeleteFileTasklet implements Tasklet, InitializingBean {

    private Resource[] resources;
    private static final Logger LOGGER = LoggerFactory.getLogger(DeleteFileTasklet.class);

    @Override
    public void afterPropertiesSet() throws Exception {
        Assert.notNull(resources, "The 'resources' property must be provided");
    }

    @Override
    public RepeatStatus execute(StepContribution contribution, ChunkContext chunkContext) throws Exception {
        List<Resource> files = resources != null ? Arrays.asList(resources) : Collections.EMPTY_LIST;

        /*
         * We must delete this on JVM shutdown in order to allow close() of ItemStream coming afterwards.
         */
        files.stream().flatMap(resource -> {
            Stream<File> result = Stream.<File>empty();

            LOGGER.info("Deleting file {}...", resource.getFilename());

            try {
                result = Stream.of(resource.getFile());
            } catch (IOException e) {
                LOGGER.error("Cannot retrieve the File from this Resource", e);
            }

            return result;
        }).filter(file -> {
            contribution.incrementWriteCount(1);
            return !file.delete();
        }).forEach(File::deleteOnExit);

        return RepeatStatus.FINISHED;
    }

    public void setResources(Resource[] resources) {
        this.resources = resources;
    }
}