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/*
* Copyright (c) 2001-2017, Zoltan Farkas All Rights Reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Additionally licensed with:
*
* 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 org.spf4j.io;
import edu.umd.cs.findbugs.annotations.CleanupObligation;
import edu.umd.cs.findbugs.annotations.DischargesObligation;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import java.io.IOException;
import java.io.OutputStream;
import java.io.Writer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CodingErrorAction;
/**
* {@link OutputStream} implementation that transforms a byte stream to a
* character stream using a specified character set encoding and writes the resulting
* stream to a {@link Writer}. The stream is transformed using a
* {@link CharsetDecoder} object, guaranteeing that all character set
* encodings supported by the JRE are handled correctly.
*
* The output of the {@link CharsetDecoder} is buffered using a fixed size buffer.
* This implies that the data is written to the underlying {@link Writer} in chunks
* that are no larger than the size of this buffer. By default, the buffer is
* flushed only when it overflows or when {@link #flush()} or {@link #close()}
* is called. In general there is therefore no need to wrap the underlying {@link Writer}
* in a {@link java.io.BufferedWriter}. {@link WriterOutputStream} can also
* be instructed to flush the buffer after each write operation. In this case, all
* available data is written immediately to the underlying {@link Writer}, implying that
* the current position of the {@link Writer} is correlated to the current position
* of the {@link WriterOutputStream}.
*
* {@link WriterOutputStream} implements the inverse transformation of {@link java.io.OutputStreamWriter};
* in the following example, writing to {@code out2} would have the same result as writing to
* {@code out} directly (provided that the byte sequence is legal with respect to the
* character set encoding):
*
* OutputStream out = ...
* Charset cs = ...
* OutputStreamWriter writer = new OutputStreamWriter(out, cs);
* WriterOutputStream out2 = new WriterOutputStream(writer, cs);
* {@link WriterOutputStream} implements the same transformation as {@link java.io.InputStreamReader},
* except that the control flow is reversed: both classes transform a byte stream
* into a character stream, but {@link java.io.InputStreamReader} pulls data from the underlying stream,
* while {@link WriterOutputStream} pushes it to the underlying stream.
*
* Note that while there are use cases where there is no alternative to using
* this class, very often the need to use this class is an indication of a flaw
* in the design of the code. This class is typically used in situations where an existing
* API only accepts an {@link OutputStream} object, but where the stream is known to represent
* character data that must be decoded for further use.
*
* Instances of {@link WriterOutputStream} are not thread safe.
*
* @see org.apache.commons.io.input.ReaderInputStream
*
* @since 7.2.25
*/
@CleanupObligation
public final class WriterOutputStream extends AppendableOutputStream {
private static final int DEFAULT_BUFFER_SIZE = 8192;
private final Writer writer;
/**
* Constructs a new {@link WriterOutputStream} with a default output buffer size of
* 1024 characters. The output buffer will only be flushed when it overflows or when
* {@link #flush()} or {@link #close()} is called.
*
* @param writer the target {@link Writer}
* @param decoder the charset decoder
* @since 2.1
*/
public WriterOutputStream(final Writer writer, final CharsetDecoder decoder) {
this(writer, decoder, DEFAULT_BUFFER_SIZE);
}
/**
* Constructs a new {@link WriterOutputStream}.
*
* @param writer the target {@link Writer}
* @param decoder the charset decoder
* @param bufferSize the size of the output buffer in number of characters
* @since 2.1
*/
@SuppressFBWarnings("EI_EXPOSE_REP2")
public WriterOutputStream(final Writer writer, final CharsetDecoder decoder, final int bufferSize) {
super(writer, decoder, bufferSize);
this.writer = writer;
}
/**
* Constructs a new {@link WriterOutputStream}.
*
* @param writer the target {@link Writer}
* @param charset the charset encoding
* @param bufferSize the size of the output buffer in number of characters
*/
public WriterOutputStream(final Writer writer, final Charset charset, final int bufferSize) {
this(writer,
charset.newDecoder()
.onMalformedInput(CodingErrorAction.REPLACE)
.onUnmappableCharacter(CodingErrorAction.REPLACE)
.replaceWith("?"),
bufferSize);
}
/**
* Constructs a new {@link WriterOutputStream} with a default output buffer size of
* 1024 characters. The output buffer will only be flushed when it overflows or when
* {@link #flush()} or {@link #close()} is called.
*
* @param writer the target {@link Writer}
* @param charset the charset encoding
*/
public WriterOutputStream(final Writer writer, final Charset charset) {
this(writer, charset, DEFAULT_BUFFER_SIZE);
}
/**
* Constructs a new {@link WriterOutputStream}.
*
* @param writer the target {@link Writer}
* @param charsetName the name of the charset encoding
* @param bufferSize the size of the output buffer in number of characters
*/
public WriterOutputStream(final Writer writer, final String charsetName, final int bufferSize) {
this(writer, Charset.forName(charsetName), bufferSize);
}
/**
* Constructs a new {@link WriterOutputStream} with a default output buffer size of
* 1024 characters. The output buffer will only be flushed when it overflows or when
* {@link #flush()} or {@link #close()} is called.
*
* @param writer the target {@link Writer}
* @param charsetName the name of the charset encoding
*/
public WriterOutputStream(final Writer writer, final String charsetName) {
this(writer, charsetName, DEFAULT_BUFFER_SIZE);
}
/**
* Flush the stream. Any remaining content accumulated in the output buffer
* will be written to the underlying {@link Writer}. After that
* {@link Writer#flush()} will be called.
* @throws IOException if an I/O error occurs
*/
@Override
public void flush() throws IOException {
super.flush();
writer.flush();
}
/**
* Close the stream. Any remaining content accumulated in the output buffer
* will be written to the underlying {@link Writer}. After that
* {@link Writer#close()} will be called.
* @throws IOException if an I/O error occurs
*/
@Override
@DischargesObligation
public void close() throws IOException {
super.close();
writer.close();
}
/**
* Flush the output.
*
* @throws IOException if an I/O error occurs
*/
@Override
protected void flushOutput() throws IOException {
if (decoderOut.position() > 0) {
writer.write(decoderOut.array(), 0, decoderOut.position());
decoderOut.rewind();
}
}
@Override
public String toString() {
return "WriterOutputStream{" + "writer=" + writer + '}';
}
}