/*
* 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 java.nio.channels;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.Writer;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.spi.AbstractInterruptibleChannel;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import org.apache.harmony.nio.internal.IOUtil;
/**
* This class provides several utilities to get I/O streams from channels.
*/
public final class Channels {
/*
* Not intended to be instantiated.
*/
private Channels() {
super();
}
/**
* Returns an input stream on the given channel. The resulting stream has
* the following properties:
* <ul>
* <li>If the stream is closed, then the underlying channel is closed as
* well.</li>
* <li>It is thread safe.</li>
* <li>It throws an {@link IllegalBlockingModeException} if the channel is
* in non-blocking mode and {@code read} is called.</li>
* <li>Neither {@code mark} nor {@code reset} is supported.</li>
* <li>It is not buffered.</li>
* </ul>
*
* @param channel
* the channel to be wrapped by an InputStream.
* @return an InputStream that takes bytes from the given byte channel.
*/
public static InputStream newInputStream(ReadableByteChannel channel) {
return new ReadableByteChannelInputStream(channel);
}
/**
* Returns an output stream on the given channel. The resulting stream has
* the following properties:
* <ul>
* <li>If the stream is closed, then the underlying channel is closed as
* well.</li>
* <li>It is thread safe.</li>
* <li>It throws an {@link IllegalBlockingModeException} if the channel is
* in non-blocking mode and {@code write} is called.</li>
* <li>It is not buffered.</li>
* </ul>
*
* @param channel
* the channel to be wrapped by an OutputStream.
* @return an OutputStream that puts bytes onto the given byte channel.
*/
public static OutputStream newOutputStream(WritableByteChannel channel) {
return new WritableByteChannelOutputStream(channel);
}
/**
* Returns a readable channel on the given input stream. The resulting
* channel has the following properties:
* <ul>
* <li>If the channel is closed, then the underlying stream is closed as
* well.</li>
* <li>It is not buffered.</li>
* </ul>
*
* @param inputStream
* the stream to be wrapped by a byte channel.
* @return a byte channel that reads bytes from the input stream.
*/
public static ReadableByteChannel newChannel(InputStream inputStream) {
return new ReadableByteChannelImpl(inputStream);
}
/**
* Returns a writable channel on the given output stream.
*
* The resulting channel has following properties:
* <ul>
* <li>If the channel is closed, then the underlying stream is closed as
* well.</li>
* <li>It is not buffered.</li>
* </ul>
*
* @param outputStream
* the stream to be wrapped by a byte channel.
* @return a byte channel that writes bytes to the output stream.
*/
public static WritableByteChannel newChannel(OutputStream outputStream) {
return new WritableByteChannelImpl(outputStream);
}
/**
* Returns a reader that decodes bytes from a channel.
*
* @param channel
* the Channel to be read.
* @param decoder
* the Charset decoder to be used.
* @param minBufferCapacity
* The minimum size of the byte buffer, -1 means to use the
* default size.
* @return the reader.
*/
public static Reader newReader(ReadableByteChannel channel,
CharsetDecoder decoder, int minBufferCapacity) {
return new ByteChannelReader(new ReaderInputStream(channel), decoder,
minBufferCapacity);
}
/**
* Returns a reader that decodes bytes from a channel. This method creates a
* reader with a buffer of default size.
*
* @param channel
* the Channel to be read.
* @param charsetName
* the name of the charset.
* @return the reader.
* @throws java.nio.charset.UnsupportedCharsetException
* if the given charset name is not supported.
*/
public static Reader newReader(ReadableByteChannel channel,
String charsetName) {
return newReader(channel, Charset.forName(charsetName).newDecoder(), -1);
}
/**
* Returns a writer that encodes characters with the specified
* {@code encoder} and sends the bytes to the specified channel.
*
* @param channel
* the Channel to write to.
* @param encoder
* the CharsetEncoder to be used.
* @param minBufferCapacity
* the minimum size of the byte buffer, -1 means to use the
* default size.
* @return the writer.
*/
public static Writer newWriter(WritableByteChannel channel,
CharsetEncoder encoder, int minBufferCapacity) {
return new ByteChannelWriter(new WritableByteChannelOutputStream(
channel), encoder, minBufferCapacity);
}
/**
* Returns a writer that encodes characters with the specified
* {@code encoder} and sends the bytes to the specified channel. This method
* creates a writer with a buffer of default size.
*
* @param channel
* the Channel to be written to.
* @param charsetName
* the name of the charset.
* @return the writer.
* @throws java.nio.charset.UnsupportedCharsetException
* if the given charset name is not supported.
*/
public static Writer newWriter(WritableByteChannel channel,
String charsetName) {
return newWriter(channel, Charset.forName(charsetName).newEncoder(), -1);
}
/*
* wrap a byte array to a ByteBuffer
*/
static ByteBuffer wrapByteBuffer(byte[] bytes, int offset, int length) {
ByteBuffer buffer = ByteBuffer.wrap(bytes);
int newLimit = offset + length <= buffer.capacity() ? offset + length
: buffer.capacity();
buffer.limit(newLimit);
buffer.position(offset);
return buffer;
}
private static class ChannelInputStream extends InputStream {
protected ReadableByteChannel channel;
public ChannelInputStream(ReadableByteChannel aChannel) {
super();
channel = aChannel;
}
@Override
public synchronized int read() throws IOException {
byte[] oneByte = new byte[1];
int n = read(oneByte);
if (n == 1) {
// reads a single byte 0-255
return oneByte[0] & 0xff;
}
return -1;
}
@Override
public synchronized void close() throws IOException {
channel.close();
}
}
/*
* Wrapper class used for newInputStream(ReadableByteChannel channel)
*/
private static class ReadableByteChannelInputStream extends
ChannelInputStream {
public ReadableByteChannelInputStream(ReadableByteChannel aChannel) {
super(aChannel);
}
@Override
public synchronized int read(byte[] target, int offset, int length)
throws IOException {
// avoid int overflow, check null target
if (length + offset > target.length || length < 0 || offset < 0) {
throw new ArrayIndexOutOfBoundsException();
}
if (0 == length) {
return 0;
}
if (channel instanceof SelectableChannel) {
if (!((SelectableChannel) channel).isBlocking()) {
throw new IllegalBlockingModeException();
}
}
ByteBuffer buffer = ByteBuffer.wrap(target, offset, length);
return channel.read(buffer);
}
}
/*
* Wrapper class used for newReader(ReadableByteChannel channel,
* CharsetDecoder decoder, int minBufferCapacity)
*/
private static class ReaderInputStream extends ChannelInputStream {
public ReaderInputStream(ReadableByteChannel aChannel) {
super(aChannel);
}
@Override
public synchronized int read(byte[] target, int offset, int length)
throws IOException {
// avoid int overflow, check null target
if (length + offset > target.length || length < 0 || offset < 0) {
throw new ArrayIndexOutOfBoundsException();
}
if (0 == length) {
return 0;
}
ByteBuffer buffer = ByteBuffer.wrap(target, offset, length);
return channel.read(buffer);
}
}
/*
* Wrapper class used for newOutputStream(WritableByteChannel channel)
*/
private static class WritableByteChannelOutputStream extends OutputStream {
private WritableByteChannel channel;
public WritableByteChannelOutputStream(WritableByteChannel aChannel) {
super();
channel = aChannel;
}
@Override
public synchronized void write(int oneByte) throws IOException {
byte[] wrappedByte = new byte[1];
wrappedByte[0] = (byte) oneByte;
write(wrappedByte);
}
@Override
public synchronized void write(byte[] source, int offset, int length)
throws IOException {
// avoid int overflow, check null source
if (length + offset > source.length || length < 0 || offset < 0) {
throw new ArrayIndexOutOfBoundsException();
}
if (0 == length) {
return;
}
if (channel instanceof SelectableChannel) {
if (!((SelectableChannel) channel).isBlocking()) {
throw new IllegalBlockingModeException();
}
}
ByteBuffer buffer = ByteBuffer.wrap(source, offset, length);
channel.write(buffer);
}
@Override
public synchronized void close() throws IOException {
channel.close();
}
}
/*
* Wrapper class used for newChannel(InputStream inputStream)
*/
private static class ReadableByteChannelImpl extends
AbstractInterruptibleChannel implements ReadableByteChannel {
private InputStream inputStream;
ReadableByteChannelImpl(InputStream aInputStream) {
super();
inputStream = aInputStream;
}
public synchronized int read(ByteBuffer target) throws IOException {
if (!isOpen()) {
throw new ClosedChannelException();
}
int bytesRemain = target.remaining();
byte[] bytes = new byte[bytesRemain];
int readCount = 0;
try {
begin();
readCount = inputStream.read(bytes);
} finally {
end(readCount >= 0);
}
if (readCount > 0) {
target.put(bytes, 0, readCount);
}
return readCount;
}
@Override
protected void implCloseChannel() throws IOException {
inputStream.close();
}
}
/*
* Wrapper class used for newChannel(OutputStream outputStream)
*/
private static class WritableByteChannelImpl extends
AbstractInterruptibleChannel implements WritableByteChannel {
private OutputStream outputStream;
WritableByteChannelImpl(OutputStream aOutputStream) {
super();
outputStream = aOutputStream;
}
public synchronized int write(ByteBuffer source) throws IOException {
if (!isOpen()) {
throw new ClosedChannelException();
}
int bytesRemain = source.remaining();
if (bytesRemain == 0) {
return 0;
}
byte[] buf = new byte[bytesRemain];
source.get(buf);
try {
begin();
outputStream.write(buf, 0, bytesRemain);
} finally {
end(bytesRemain >= 0);
}
return bytesRemain;
}
@Override
protected void implCloseChannel() throws IOException {
outputStream.close();
}
}
/*
* Wrapper class used for newReader(ReadableByteChannel channel,
* CharsetDecoder decoder, int minBufferCapacity)
*/
private static class ByteChannelReader extends Reader {
private InputStream inputStream;
private static final int BUFFER_SIZE = 8192;
CharsetDecoder decoder;
ByteBuffer bytes;
CharBuffer chars;
public ByteChannelReader(InputStream aInputStream,
CharsetDecoder aDecoder, int minBufferCapacity) {
super(aInputStream);
aDecoder.reset();
inputStream = aInputStream;
int bufferSize = Math.max(minBufferCapacity, BUFFER_SIZE);
bytes = ByteBuffer.allocate(bufferSize);
chars = CharBuffer.allocate(bufferSize);
decoder = aDecoder;
chars.limit(0);
}
@Override
public void close() throws IOException {
synchronized (lock) {
decoder = null;
if (inputStream != null) {
inputStream.close();
inputStream = null;
}
}
}
@Override
public boolean ready() {
synchronized (lock) {
if (null == inputStream) {
return false;
}
try {
return chars.limit() > chars.position()
|| inputStream.available() > 0;
} catch (IOException e) {
return false;
}
}
}
@Override
public int read() throws IOException {
return IOUtil.readInputStreamReader(inputStream, bytes, chars,
decoder, lock);
}
@Override
public int read(char[] buf, int offset, int length) throws IOException {
return IOUtil.readInputStreamReader(buf, offset, length,
inputStream, bytes, chars, decoder, lock);
}
}
/*
* Wrapper class used for newWriter(WritableByteChannel channel,
* CharsetEncoder encoder, int minBufferCapacity)
*/
private static class ByteChannelWriter extends Writer {
private static final int BUFFER_SIZE = 8192;
private OutputStream outputStream;
private CharsetEncoder encoder;
private ByteBuffer byteBuf;
public ByteChannelWriter(OutputStream aOutputStream,
CharsetEncoder aEncoder, int minBufferCap) {
super(aOutputStream);
aEncoder.charset();
outputStream = aOutputStream;
byteBuf = ByteBuffer.allocate(Math.max(minBufferCap, BUFFER_SIZE));
encoder = aEncoder;
}
@Override
public void close() throws IOException {
synchronized (lock) {
if (encoder != null) {
flush();
outputStream.flush();
outputStream.close();
encoder = null;
byteBuf = null;
}
}
}
@Override
public void flush() throws IOException {
IOUtil
.flushOutputStreamWriter(outputStream, byteBuf, encoder,
lock);
}
@Override
public void write(char[] buf, int offset, int count) throws IOException {
IOUtil.writeOutputStreamWriter(buf, offset, count, outputStream,
byteBuf, encoder, lock);
}
@Override
public void write(int oneChar) throws IOException {
IOUtil.writeOutputStreamWriter(oneChar, outputStream, byteBuf,
encoder, lock);
}
@Override
public void write(String str, int offset, int count) throws IOException {
IOUtil.writeOutputStreamWriter(str, offset, count, outputStream,
byteBuf, encoder, lock);
}
}
}