From: David ‘Bombe’ Roden <bombe@pterodactylus.net>
Date: Thu, 10 Apr 2008 16:40:13 +0000 (+0000)
Subject: add limited input stream
X-Git-Url: https://git.pterodactylus.net/?a=commitdiff_plain;h=87607d6d051b828515044b71a7ddb549e13deae1;p=jSite2.git

add limited input stream

git-svn-id: http://trooper/svn/projects/jSite/trunk@699 c3eda9e8-030b-0410-8277-bc7414b0a119
---

diff --git a/src/net/pterodactylus/util/io/LimitedInputStream.java b/src/net/pterodactylus/util/io/LimitedInputStream.java
new file mode 100644
index 0000000..8e23f24
--- /dev/null
+++ b/src/net/pterodactylus/util/io/LimitedInputStream.java
@@ -0,0 +1,134 @@
+/**
+ * © 2008 INA Service GmbH
+ */
+package net.pterodactylus.util.io;
+
+import java.io.FilterInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * A wrapper around an {@link InputStream} that only supplies a limit number of
+ * bytes from the underlying input stream.
+ * 
+ * @author <a href="mailto:dr@ina-germany.de">David Roden</a>
+ * @version $Id$
+ */
+public class LimitedInputStream extends FilterInputStream {
+
+	/** The remaining number of bytes that can be read. */
+	private long remaining;
+
+	/**
+	 * Creates a new LimitedInputStream that supplies at most
+	 * <code>length</code> bytes from the given input stream.
+	 * 
+	 * @param inputStream
+	 *            The input stream
+	 * @param length
+	 *            The number of bytes to read
+	 */
+	public LimitedInputStream(InputStream inputStream, long length) {
+		super(inputStream);
+		remaining = length;
+	}
+
+	/**
+	 * @see java.io.FilterInputStream#available()
+	 */
+	@Override
+	public synchronized int available() throws IOException {
+		return (int) Math.min(super.available(), Math.min(Integer.MAX_VALUE, remaining));
+	}
+
+	/**
+	 * @see java.io.FilterInputStream#read()
+	 */
+	@Override
+	public synchronized int read() throws IOException {
+		int read = -1;
+		if (remaining > 0) {
+			read = super.read();
+			remaining--;
+		}
+		return read;
+	}
+
+	/**
+	 * @see java.io.FilterInputStream#read(byte[], int, int)
+	 */
+	@Override
+	public synchronized int read(byte[] b, int off, int len) throws IOException {
+		if (remaining == 0) {
+			return -1;
+		}
+		int toCopy = (int) Math.min(len, Math.min(remaining, Integer.MAX_VALUE));
+		int read = super.read(b, off, toCopy);
+		remaining -= read;
+		return read;
+	}
+
+	/**
+	 * @see java.io.FilterInputStream#skip(long)
+	 */
+	@Override
+	public synchronized long skip(long n) throws IOException {
+		if (n < 0) {
+			return 0;
+		}
+		long skipped = super.skip(Math.min(n, remaining));
+		remaining -= skipped;
+		return skipped;
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * 
+	 * This method does nothing, as {@link #mark(int)} and {@link #reset()} are
+	 * not supported.
+	 * 
+	 * @see java.io.FilterInputStream#mark(int)
+	 */
+	@Override
+	public void mark(int readlimit) {
+		/* do nothing. */
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * 
+	 * @see java.io.FilterInputStream#markSupported()
+	 * @return <code>false</code>
+	 */
+	@Override
+	public boolean markSupported() {
+		return false;
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * 
+	 * This method does nothing, as {@link #mark(int)} and {@link #reset()} are
+	 * not supported.
+	 * 
+	 * @see java.io.FilterInputStream#reset()
+	 */
+	@Override
+	public void reset() throws IOException {
+		/* do nothing. */
+	}
+
+	/**
+	 * Consumes the input stream, i.e. read all bytes until the limit is
+	 * reached.
+	 * 
+	 * @throws IOException
+	 *             if an I/O error occurs
+	 */
+	public void consume() throws IOException {
+		while (remaining > 0) {
+			skip(remaining);
+		}
+	}
+
+}