add improved stream copier

git-svn-id: http://trooper/svn/projects/jSite/trunk@616 c3eda9e8-030b-0410-8277-bc7414b0a119

diff --git a/src/net/pterodactylus/util/io/StreamCopier.java b/src/net/pterodactylus/util/io/StreamCopier.java
new file mode 100644 (file)
index 0000000..d1d0b11
--- /dev/null
+++ b/src/net/pterodactylus/util/io/StreamCopier.java
@@ -0,0 +1,124 @@
+/*
+ * jSite2 - StreamCopier.java -
+ * Copyright © 2008 David Roden
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+package net.pterodactylus.util.io;
+
+import java.io.EOFException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+/**
+ * Helper class that copies bytes from an {@link InputStream} to an
+ * {@link OutputStream}.
+ * 
+ * @author <a href="mailto:dr@ina-germany.de">David Roden</a>
+ * @version $Id$
+ */
+public class StreamCopier {
+
+       /** Default buffer size is 64k. */
+       private static final int DEFAULT_BUFFER_SIZE = 1 << 16;
+
+       /** The current buffer size. */
+       private static int bufferSize = DEFAULT_BUFFER_SIZE;
+
+       /**
+        * Sets the buffer size for following transfers.
+        * 
+        * @param bufferSize
+        *            The new buffer size
+        */
+       public static void setBufferSize(int bufferSize) {
+               StreamCopier.bufferSize = bufferSize;
+       }
+
+       /**
+        * Copies <code>length</code> bytes from the source input stream to the
+        * destination output stream. If <code>length</code> is <code>-1</code>
+        * as much bytes as possible will be copied (i.e. until
+        * {@link InputStream#read()} returns <code>-1</code> to signal the end of
+        * the stream).
+        * 
+        * @param source
+        *            The input stream to read from
+        * @param destination
+        *            The output stream to write to
+        * @param length
+        *            The number of bytes to copy
+        * @throws IOException
+        *             if an I/O error occurs
+        */
+       public static void copy(InputStream source, OutputStream destination, long length) throws IOException {
+               long remaining = length;
+               byte[] buffer = new byte[bufferSize];
+               int read = 0;
+               while ((remaining == -1) || (remaining > 0)) {
+                       read = source.read(buffer, 0, ((remaining > bufferSize) || (remaining == -1)) ? bufferSize : (int) remaining);
+                       if (read == -1) {
+                               if (length == -1) {
+                                       return;
+                               }
+                               throw new EOFException("stream reached eof");
+                       }
+                       destination.write(buffer, 0, read);
+                       remaining -= read;
+               }
+       }
+
+       /**
+        * Copies as much bytes as possible (i.e. until {@link InputStream#read()}
+        * returns <code>-1</code>) from the source input stream to the
+        * destination output stream.
+        * 
+        * @param source
+        *            The input stream to read from
+        * @param destination
+        *            The output stream to write to
+        * @throws IOException
+        *             if an I/O error occurs
+        */
+       public static void copy(InputStream source, OutputStream destination) throws IOException {
+               copy(source, destination, -1);
+       }
+
+       /**
+        * Finds the length of the input stream by reading until
+        * {@link InputStream#read(byte[])} returns <code>-1</code>.
+        * 
+        * @param source
+        *            The input stream to measure
+        * @return The length of the input stream in bytes
+        * @throws IOException
+        *             if an I/O error occurs
+        */
+       public static long findLength(InputStream source) throws IOException {
+               long length = 0;
+               byte[] buffer = new byte[bufferSize];
+               int read = 0;
+               while (read != -1) {
+                       read = source.read(buffer);
+                       if (read != -1) {
+                               length += read;
+                       }
+               }
+               return length;
+       }
+
+}