FileCopyUtils.java

/**
 * Copyright 2010-2015 Axel Fontaine
 * <p/>
 * 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
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * 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.contrastsecurity.cassandra.migration.utils;

import java.io.*;

/**
 * Utility class for copying files and their contents. Inspired by Spring's own.
 */
public class FileCopyUtils {
    /**
     * Prevent instantiation.
     */
    private FileCopyUtils() {
        // Do nothing
    }

    /**
     * Copy the contents of the given Reader into a String.
     * Closes the reader when done.
     *
     * @param in the reader to copy from
     * @return the String that has been copied to
     * @throws IOException in case of I/O errors
     */
    public static String copyToString(Reader in) throws IOException {
        StringWriter out = new StringWriter();
        copy(in, out);
        String str = out.toString();

        //Strip UTF-8 BOM if necessary
        if (str.startsWith("\ufeff")) {
            return str.substring(1);
        }

        return str;
    }

    /**
     * Copy the contents of the given InputStream into a new byte array.
     * Closes the stream when done.
     *
     * @param in the stream to copy from
     * @return the new byte array that has been copied to
     * @throws IOException in case of I/O errors
     */
    public static byte[] copyToByteArray(InputStream in) throws IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream(4096);
        copy(in, out);
        return out.toByteArray();
    }

    /**
     * Copy the contents of the given Reader to the given Writer.
     * Closes both when done.
     *
     * @param in  the Reader to copy from
     * @param out the Writer to copy to
     * @throws IOException in case of I/O errors
     */
    private static void copy(Reader in, Writer out) throws IOException {
        try {
            char[] buffer = new char[4096];
            int bytesRead;
            while ((bytesRead = in.read(buffer)) != -1) {
                out.write(buffer, 0, bytesRead);
            }
            out.flush();
        } finally {
            try {
                in.close();
            } catch (IOException ex) {
                //Ignore
            }
            try {
                out.close();
            } catch (IOException ex) {
                //Ignore
            }
        }
    }

    /**
     * Copy the contents of the given InputStream to the given OutputStream.
     * Closes both streams when done.
     *
     * @param in  the stream to copy from
     * @param out the stream to copy to
     * @return the number of bytes copied
     * @throws IOException in case of I/O errors
     */
    private static int copy(InputStream in, OutputStream out) throws IOException {
        try {
            int byteCount = 0;
            byte[] buffer = new byte[4096];
            int bytesRead;
            while ((bytesRead = in.read(buffer)) != -1) {
                out.write(buffer, 0, bytesRead);
                byteCount += bytesRead;
            }
            out.flush();
            return byteCount;
        } finally {
            try {
                in.close();
            } catch (IOException ex) {
                //Ignore
            }
            try {
                out.close();
            } catch (IOException ex) {
                //Ignore
            }
        }
    }
}