org.openmdx.base.io.ReaderInputStream Maven / Gradle / Ivy
/*
* 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.openmdx.base.io;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
/**
* Adapts a Reader as an InputStream.
* Adapted from StringInputStream.
*
*/
public class ReaderInputStream extends InputStream {
private static final int BYTE_MASK = 0xFF;
/** Source Reader */
private Reader in;
private String encoding = 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 = encoding;
}
}
/**
* 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) {
return -1;
} else {
result = buf[0];
}
}
return result & BYTE_MASK;
}
/**
* 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 {
int length = len;
if (in == null) {
throw new IOException("Stream Closed");
}
if (length == 0) {
return 0;
}
while (slack == null) {
char[] buf = new char[length]; // 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 (length > slack.length - begin) {
length = slack.length - begin;
}
System.arraycopy(slack, begin, b, off, length);
if ((begin += length) >= slack.length) {
slack = null;
}
return length;
}
/**
* Marks the read limit of the Reader.
*
* @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;
}
return 0;
}
/**
* @return false - mark is not supported
*/
@Override
public boolean markSupported () {
return false; // would be imprecise
}
/**
* Resets the Reader.
*
* @exception IOException if the Reader 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 Reader.
*
* @exception IOException if the original Reader fails to be closed
*/
@Override
public synchronized void close() throws IOException {
if (in != null) {
in.close();
slack = null;
in = null;
}
}
}