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/*
* Copyright 2012 Taro L. Saito
*
* Licensed 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 xerial.core.io;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.nio.charset.Charset;
/**
* Adapts a Reader as an InputStream. Adapted from
* StringInputStream.
*
*/
public class ReaderInputStream extends InputStream {
/** Source Reader */
private Reader in;
private Charset encoding = Charset.forName(System.getProperty("file.encoding"));
private byte[] slack;
private int begin;
/**
* Construct a ReaderInputStream for the specified
* Reader.
*
* @param reader
* Reader. Must not be null.
*/
public ReaderInputStream(Reader reader) {
in = reader;
}
/**
* Construct a ReaderInputStream for the specified
* Reader, with the specified encoding.
*
* @param reader
* non-null Reader.
* @param encoding
* non-null String encoding.
*/
public ReaderInputStream(Reader reader, String encoding) {
this(reader);
if (encoding == null) {
throw new IllegalArgumentException("encoding must not be null");
}
else {
this.encoding = Charset.forName(encoding);
}
}
/**
* Construct a ReaderInputStream for the specified
* Reader, with the specified encoding.
*
* @param reader
* non-null Reader.
* @param charset
* non-null Charset
*/
public ReaderInputStream(Reader reader, Charset charset) {
this(reader);
if (encoding == null) {
throw new IllegalArgumentException("encoding must not be null");
}
else {
this.encoding = charset;
}
}
/**
* Reads from the Reader, returning the same value.
*
* @return the value of the next character in the Reader.
*
* @exception IOException
* if the original Reader fails to be read
*/
@Override
public synchronized int read() throws IOException {
if (in == null) {
throw new IOException("Stream Closed");
}
byte result;
if (slack != null && begin < slack.length) {
result = slack[begin];
if (++begin == slack.length) {
slack = null;
}
}
else {
byte[] buf = new byte[1];
if (read(buf, 0, 1) <= 0) {
result = -1;
}
result = buf[0];
}
if (result < -1) {
result += 256;
}
return result;
}
/**
* Reads from the Reader into a byte array
*
* @param b
* the byte array to read into
* @param off
* the offset in the byte array
* @param len
* the length in the byte array to fill
* @return the actual number read into the byte array, -1 at the end of the
* stream
* @exception IOException
* if an error occurs
*/
@Override
public synchronized int read(byte[] b, int off, int len) throws IOException {
if (in == null) {
throw new IOException("Stream Closed");
}
while (slack == null) {
char[] buf = new char[len]; // might read too much
int n = in.read(buf);
if (n == -1) {
return -1;
}
if (n > 0) {
slack = new String(buf, 0, n).getBytes(encoding);
begin = 0;
}
}
if (len > slack.length - begin) {
len = slack.length - begin;
}
System.arraycopy(slack, begin, b, off, len);
if ((begin += len) >= slack.length) {
slack = null;
}
return len;
}
/**
* Marks the read limit of the StringReader.
*
* @param limit
* the maximum limit of bytes that can be read before the mark
* position becomes invalid
*/
@Override
public synchronized void mark(final int limit) {
try {
in.mark(limit);
}
catch (IOException ioe) {
throw new RuntimeException(ioe.getMessage());
}
}
/**
* @return the current number of bytes ready for reading
* @exception IOException
* if an error occurs
*/
@Override
public synchronized int available() throws IOException {
if (in == null) {
throw new IOException("Stream Closed");
}
if (slack != null) {
return slack.length - begin;
}
if (in.ready()) {
return 1;
}
else {
return 0;
}
}
/**
* @return false - mark is not supported
*/
@Override
public boolean markSupported() {
return false; // would be imprecise
}
/**
* Resets the StringReader.
*
* @exception IOException
* if the StringReader fails to be reset
*/
@Override
public synchronized void reset() throws IOException {
if (in == null) {
throw new IOException("Stream Closed");
}
slack = null;
in.reset();
}
/**
* Closes the Stringreader.
*
* @exception IOException
* if the original StringReader fails to be closed
*/
@Override
public synchronized void close() throws IOException {
if(in != null)
in.close();
slack = null;
in = null;
}
}