FileUtils.java

/*******************************************************************************
 * Copyright 2006 - 2012 Vienna University of Technology,
 * Department of Software Technology and Interactive Systems, IFS
 * 
 * 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 eu.scape_project.planning.utils;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Serializable;
import java.net.URI;
import java.net.URISyntaxException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * File utilities.
 */
public final class FileUtils implements Serializable {
    private static final long serialVersionUID = -2554713564317100326L;

    private static final int WRITE_BUFFER_SIZE = 1024;

    /**
     * Default separator between filename parts.
     */
    public static final String FILENAME_SEPARATOR = "-";

    private static final Logger log = LoggerFactory.getLogger(FileUtils.class);

    /**
     * Private constructor to avoid instantiation.
     */
    private FileUtils() {
        throw new AssertionError("Instantiating utility class.");
    }

    /**
     * Returns a file handle for the resource with the given name.
     * 
     * @param name
     *            resource name
     * @return the resource as file
     * @throws URISyntaxException
     *             if the resource URL is invalid
     */
    public static File getResourceFile(String name) throws URISyntaxException {
        URI uri = Thread.currentThread().getContextClassLoader().getResource(name).toURI();
        return new File(uri);
    }

    /**
     * Reads all bytes from the given input stream and returns a byte array.
     * 
     * @param in
     *            the input stream to read
     * @return the data read from the input stream
     * @throws IOException
     *             if the data cannot be read
     */
    public static byte[] inputStreamToBytes(InputStream in) throws IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream(WRITE_BUFFER_SIZE);
        byte[] buffer = new byte[WRITE_BUFFER_SIZE];
        int len;

        try {
            while ((len = in.read(buffer)) >= 0) {
                out.write(buffer, 0, len);
            }
        } finally {
            out.close();
            in.close();
        }

        return out.toByteArray();
    }

    /**
     * Reads all bytes from the given file and returns a byte array.
     * 
     * @param file
     *            the file to read
     * @return the data read from the file
     * @throws IOException
     *             if the file cannot be read
     */
    public static byte[] getBytesFromFile(File file) throws IOException {
        if (file == null) {
            return null;
        }
        InputStream is = new BufferedInputStream(new FileInputStream(file));
        byte[] bytes;
        try {

            // Get the size of the file
            long length = file.length();

            if (length > Integer.MAX_VALUE) {
                throw new IOException("File is too large " + file.getName());
            }

            // Create the byte array to hold the data
            bytes = new byte[(int) length];

            // Read in the bytes
            int offset = 0;
            int numRead = 0;
            while (offset < bytes.length && (numRead = is.read(bytes, offset, bytes.length - offset)) >= 0) {
                offset += numRead;
            }

            // Ensure all the bytes have been read in
            if (offset < bytes.length) {
                throw new IOException("Could not completely read file " + file.getName());
            }

        } finally {
            // Close the input stream and return bytes
            is.close();
        }
        return bytes;
    }

    /**
     * Replaces the extension of the provided filename with a new extension.
     * 
     * @param filename
     *            the filename to process
     * @param newExtension
     *            new extension to add
     * @return the filename with new extension
     */
    public static String replaceExtension(String filename, String newExtension) {
        return filename.substring(0, filename.lastIndexOf(".")) + "." + newExtension;
    }

    /**
     * Creates a filename from the provided string.
     * 
     * @param value
     *            the value to use
     * @return the value as well-formed filename
     */
    public static String makeFilename(String value) {
        if (value == null) {
            return "";
        }
        return value.replaceAll("\\s", "_").replaceAll("[^\\w-\\.]", "");
    }

    /**
     * Writes content from an input stream to the output stream.
     * 
     * @param in
     *            input stream to read from
     * @param out
     *            output stream to write to
     * @throws IOException
     *             if an error occurred during write
     */
    public static void writeToFile(InputStream in, OutputStream out) throws IOException {
        InputStream bufIn = new BufferedInputStream(in);
        OutputStream bufOut = new BufferedOutputStream(out);
        try {
            byte[] buf = new byte[WRITE_BUFFER_SIZE];
            int len;
            while ((len = bufIn.read(buf)) > 0) {
                bufOut.write(buf, 0, len);
            }
        } catch (FileNotFoundException ex) {
            log.debug("Error copying file " + ex.getMessage(), ex);
        } finally {
            try {
                bufIn.close();
            } catch (Exception skip) {
            }
            try {
                bufOut.close();
            } catch (Exception skip) {
            }

        }
    }
}