de.metanome.backend.algorithm_execution.TempFileGenerator.java Source code

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Here is the source code for de.metanome.backend.algorithm_execution.TempFileGenerator.java

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/*
 * Copyright 2014 by the Metanome project
 *
 * 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 de.metanome.backend.algorithm_execution;

import de.metanome.algorithm_integration.algorithm_execution.FileCreationException;
import de.metanome.algorithm_integration.algorithm_execution.FileGenerator;
import org.apache.commons.lang3.RandomStringUtils;

import java.io.File;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.LinkedList;
import java.util.List;

/**
 * The generator builds empty, readable, writable files with random file names, that are deleted on
 * close.
 *
 * @author Jakob Zwiener
 */
public class TempFileGenerator implements FileGenerator {

    public static final String TEMP_FILE_PATH = "temp_files";
    public static final int FILE_NAME_LENGTH = 30;

    protected String pathToFolder;
    protected List<File> createdFiles;

    public TempFileGenerator() throws UnsupportedEncodingException {
        // Get path to resource dir.
        String pathToFolder = Thread.currentThread().getContextClassLoader().getResource("").getPath();
        pathToFolder += "/" + TEMP_FILE_PATH;
        this.pathToFolder = URLDecoder.decode(pathToFolder, "utf-8");
        // Create subdir.
        new File(this.pathToFolder).mkdirs();

        this.createdFiles = new LinkedList<>();
    }

    @Override
    public File getTemporaryFile() throws FileCreationException {
        String fileName = RandomStringUtils.randomAlphanumeric(FILE_NAME_LENGTH).toLowerCase();
        File tempFile = new File(pathToFolder + System.getProperty("file.separator") + fileName);

        try {
            tempFile.createNewFile();
        } catch (IOException e) {
            throw new FileCreationException("Could not create temporary file.");
        }

        // Mark the file for deletion on vm exit.
        tempFile.deleteOnExit();
        // Remember the file to be deleted on close.
        createdFiles.add(tempFile);

        return tempFile;
    }

    @Override
    public void close() {
        for (File tempFile : createdFiles) {
            try {
                tempFile.delete();
            } catch (Exception e) {
                System.out.println("A file could not be deleted.");
            }
        }
    }
}