/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.hadoop.io;
import java.io.*;
import java.net.Socket;
import org.apache.commons.logging.Log;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
/**
* An utility class for I/O related functionality.
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public class IOUtils {
/**
* Copies from one stream to another.
*
* @param in InputStrem to read from
* @param out OutputStream to write to
* @param buffSize the size of the buffer
* @param close whether or not close the InputStream and
* OutputStream at the end. The streams are closed in the finally clause.
*/
public static void copyBytes(InputStream in, OutputStream out, int buffSize, boolean close)
throws IOException {
try {
copyBytes(in, out, buffSize);
if(close) {
out.close();
out = null;
in.close();
in = null;
}
} finally {
if(close) {
closeStream(out);
closeStream(in);
}
}
}
/**
* Copies from one stream to another.
*
* @param in InputStrem to read from
* @param out OutputStream to write to
* @param buffSize the size of the buffer
*/
public static void copyBytes(InputStream in, OutputStream out, int buffSize)
throws IOException {
PrintStream ps = out instanceof PrintStream ? (PrintStream)out : null;
byte buf[] = new byte[buffSize];
int bytesRead = in.read(buf);
while (bytesRead >= 0) {
out.write(buf, 0, bytesRead);
if ((ps != null) && ps.checkError()) {
throw new IOException("Unable to write to output stream.");
}
bytesRead = in.read(buf);
}
}
/**
* Copies from one stream to another. <strong>closes the input and output streams
* at the end</strong>.
*
* @param in InputStrem to read from
* @param out OutputStream to write to
* @param conf the Configuration object
*/
public static void copyBytes(InputStream in, OutputStream out, Configuration conf)
throws IOException {
copyBytes(in, out, conf.getInt("io.file.buffer.size", 4096), true);
}
/**
* Copies from one stream to another.
*
* @param in InputStream to read from
* @param out OutputStream to write to
* @param conf the Configuration object
* @param close whether or not close the InputStream and
* OutputStream at the end. The streams are closed in the finally clause.
*/
public static void copyBytes(InputStream in, OutputStream out, Configuration conf, boolean close)
throws IOException {
copyBytes(in, out, conf.getInt("io.file.buffer.size", 4096), close);
}
/**
* Copies count bytes from one stream to another.
*
* @param in InputStream to read from
* @param out OutputStream to write to
* @param count number of bytes to copy
* @param close whether to close the streams
* @throws IOException if bytes can not be read or written
*/
public static void copyBytes(InputStream in, OutputStream out, long count,
boolean close) throws IOException {
byte buf[] = new byte[4096];
long bytesRemaining = count;
int bytesRead;
try {
while (bytesRemaining > 0) {
int bytesToRead = (int)
(bytesRemaining < buf.length ? bytesRemaining : buf.length);
bytesRead = in.read(buf, 0, bytesToRead);
if (bytesRead == -1)
break;
out.write(buf, 0, bytesRead);
bytesRemaining -= bytesRead;
}
if (close) {
out.close();
out = null;
in.close();
in = null;
}
} finally {
if (close) {
closeStream(out);
closeStream(in);
}
}
}
/**
* Reads len bytes in a loop.
*
* @param in InputStream to read from
* @param buf The buffer to fill
* @param off offset from the buffer
* @param len the length of bytes to read
* @throws IOException if it could not read requested number of bytes
* for any reason (including EOF)
*/
public static void readFully(InputStream in, byte buf[],
int off, int len) throws IOException {
int toRead = len;
while (toRead > 0) {
int ret = in.read(buf, off, toRead);
if (ret < 0) {
throw new IOException( "Premature EOF from inputStream");
}
toRead -= ret;
off += ret;
}
}
/**
* Similar to readFully(). Skips bytes in a loop.
* @param in The InputStream to skip bytes from
* @param len number of bytes to skip.
* @throws IOException if it could not skip requested number of bytes
* for any reason (including EOF)
*/
public static void skipFully(InputStream in, long len) throws IOException {
while (len > 0) {
long ret = in.skip(len);
if (ret < 0) {
throw new IOException( "Premature EOF from inputStream");
}
len -= ret;
}
}
/**
* Close the Closeable objects and <b>ignore</b> any {@link IOException} or
* null pointers. Must only be used for cleanup in exception handlers.
*
* @param log the log to record problems to at debug level. Can be null.
* @param closeables the objects to close
*/
public static void cleanup(Log log, java.io.Closeable... closeables) {
for (java.io.Closeable c : closeables) {
if (c != null) {
try {
c.close();
} catch(IOException e) {
if (log != null && log.isDebugEnabled()) {
log.debug("Exception in closing " + c, e);
}
}
}
}
}
/**
* Closes the stream ignoring {@link IOException}.
* Must only be called in cleaning up from exception handlers.
*
* @param stream the Stream to close
*/
public static void closeStream(java.io.Closeable stream) {
cleanup(null, stream);
}
/**
* Closes the socket ignoring {@link IOException}
*
* @param sock the Socket to close
*/
public static void closeSocket(Socket sock) {
if (sock != null) {
try {
sock.close();
} catch (IOException ignored) {
}
}
}
/**
* The /dev/null of OutputStreams.
*/
public static class NullOutputStream extends OutputStream {
public void write(byte[] b, int off, int len) throws IOException {
}
public void write(int b) throws IOException {
}
}
}