1 /*
   2  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.io;
  27 
  28 import java.nio.CharBuffer;
  29 
  30 /**
  31  * Utility methods for copying data between a {@link InputStream} and
  32  * {@link OutputStream} or between a {@link Readable} and a {@link Appendable}.
  33  */
  34 public final class IOUtil {
  35 
  36     // buffer size used for reading and writing
  37     private static final int BUFFER_SIZE = 8192;
  38 
  39     private IOUtil() {
  40         throw new Error("no instances");
  41     }
  42 
  43     /**
  44      * Reads all bytes from an input stream and writes them to an output stream.
  45      *
  46      * @param source the input stream to read from
  47      * @param target the output stream to write to
  48      *
  49      * @return the number of bytes successfully read and written
  50      *
  51      * @throws IOException if an I/O error occurs when reading or writing
  52      */
  53     public static long copy(InputStream source, OutputStream target)
  54             throws IOException {
  55         long totalRead = 0L;
  56         byte[] buffer = new byte[BUFFER_SIZE];
  57         int read;
  58         while ((read = source.read(buffer)) > -1) {
  59             target.write(buffer, 0, read);
  60             totalRead += read;
  61         }
  62         return totalRead;
  63     }
  64 
  65     /**
  66      * Reads all characters from an readable and writes them to an appendable.
  67      *
  68      * @param source the readable to read from
  69      * @param target the appendable to write to
  70      *
  71      * @return the number of characters successfully read and written
  72      *
  73      * @throws IOException if an I/O error occurs when reading or writing
  74      */
  75     public static long copy(Readable source, Appendable target) throws IOException {
  76         long totalRead = 0L;
  77         CharBuffer buffer = CharBuffer.allocate(BUFFER_SIZE);
  78         int read;
  79         while ((read = source.read(buffer)) > -1) {
  80             buffer.flip();
  81             target.append(buffer, 0, read);
  82             totalRead += read;
  83         }
  84         return totalRead;
  85     }
  86 }