BaseNCodecOutputStream.java
/*
* 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
*
* https://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.commons.codec.binary;
import static org.apache.commons.codec.binary.BaseNCodec.EOF;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Objects;
import org.apache.commons.codec.binary.BaseNCodec.Context;
import org.apache.commons.codec.binary.BaseNCodecOutputStream.AbstractBuilder;
/**
* Abstract superclass for Base-N output streams.
* <p>
* To write the EOF marker without closing the stream, call {@link #eof()} or use an <a href="https://commons.apache.org/proper/commons-io/">Apache Commons
* IO</a>
* <a href= "https://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/output/CloseShieldOutputStream.html" >CloseShieldOutputStream</a>.
* </p>
*
* @param <C> A BaseNCodec subclass.
* @param <T> A BaseNCodecInputStream subclass.
* @param <B> A subclass.
* @see Base16OutputStream
* @see Base32OutputStream
* @see Base64OutputStream
* @since 1.5
*/
public class BaseNCodecOutputStream<C extends BaseNCodec, T extends BaseNCodecOutputStream<C, T, B>, B extends AbstractBuilder<T, C, B>>
extends FilterOutputStream {
/**
* Builds output stream instances in {@link BaseNCodec} format.
*
* @param <T> the output stream type to build.
* @param <C> A {@link BaseNCodec} subclass.
* @param <B> the builder subclass.
* @since 1.20.0
*/
public abstract static class AbstractBuilder<T, C extends BaseNCodec, B extends AbstractBuilder<T, C, B>>
extends AbstractBaseNCodecStreamBuilder<T, C, B> {
private OutputStream outputStream;
/**
* Constructs a new instance.
*/
public AbstractBuilder() {
// super
}
/**
* Gets the input stream.
*
* @return the input stream.
*/
protected OutputStream getOutputStream() {
return outputStream;
}
/**
* Sets the input stream.
*
* @param outputStream the input stream.
* @return {@code this} instance.
*/
public B setOutputStream(final OutputStream outputStream) {
this.outputStream = outputStream;
return asThis();
}
}
private final boolean doEncode;
private final C baseNCodec;
private final byte[] singleByte = new byte[1];
private final Context context = new Context();
/**
* Constructs a new instance.
*
* @param builder A builder.
* @since 1.20.0
*/
@SuppressWarnings("resource") // Caller closes.
protected BaseNCodecOutputStream(final AbstractBuilder<T, C, B> builder) {
super(builder.getOutputStream());
this.baseNCodec = builder.getBaseNCodec();
this.doEncode = builder.getEncode();
}
/**
* Constructs a new instance.
*
* TODO should this be protected?
*
* @param outputStream the underlying output or null.
* @param basedCodec a BaseNCodec.
* @param doEncode true to encode, false to decode, TODO should be an enum?
*/
public BaseNCodecOutputStream(final OutputStream outputStream, final C basedCodec, final boolean doEncode) {
super(outputStream);
this.baseNCodec = basedCodec;
this.doEncode = doEncode;
}
/**
* Closes this output stream and releases any system resources associated with the stream.
* <p>
* To write the EOF marker without closing the stream, call {@link #eof()} or use an <a href="https://commons.apache.org/proper/commons-io/">Apache Commons
* IO</a>
* <a href= "https://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/output/CloseShieldOutputStream.html" >CloseShieldOutputStream</a>.
* </p>
*
* @throws IOException if an I/O error occurs.
*/
@Override
public void close() throws IOException {
eof();
flush();
out.close();
}
/**
* Writes EOF.
*
* @since 1.11
*/
public void eof() {
// Notify encoder of EOF (-1).
if (doEncode) {
baseNCodec.encode(singleByte, 0, EOF, context);
} else {
baseNCodec.decode(singleByte, 0, EOF, context);
}
}
/**
* Flushes this output stream and forces any buffered output bytes to be written out to the stream.
*
* @throws IOException if an I/O error occurs.
*/
@Override
public void flush() throws IOException {
flush(true);
}
/**
* Flushes this output stream and forces any buffered output bytes to be written out to the stream. If propagate is true, the wrapped stream will also be
* flushed.
*
* @param propagate boolean flag to indicate whether the wrapped OutputStream should also be flushed.
* @throws IOException if an I/O error occurs.
*/
private void flush(final boolean propagate) throws IOException {
final int avail = baseNCodec.available(context);
if (avail > 0) {
final byte[] buf = new byte[avail];
final int c = baseNCodec.readResults(buf, 0, avail, context);
if (c > 0) {
out.write(buf, 0, c);
}
}
if (propagate) {
out.flush();
}
}
/**
* Returns true if decoding behavior is strict. Decoding will raise an {@link IllegalArgumentException} if trailing bits are not part of a valid encoding.
*
* <p>
* The default is false for lenient encoding. Decoding will compose trailing bits into 8-bit bytes and discard the remainder.
* </p>
*
* @return true if using strict decoding.
* @since 1.15
*/
public boolean isStrictDecoding() {
return baseNCodec.isStrictDecoding();
}
/**
* Writes {@code len} bytes from the specified {@code b} array starting at {@code offset} to this output stream.
*
* @param array source byte array.
* @param offset where to start reading the bytes.
* @param len maximum number of bytes to write.
* @throws IOException if an I/O error occurs.
* @throws NullPointerException if the byte array parameter is null.
* @throws IndexOutOfBoundsException if offset, len or buffer size are invalid.
*/
@Override
public void write(final byte[] array, final int offset, final int len) throws IOException {
Objects.requireNonNull(array, "array");
if (offset < 0 || len < 0 || offset > array.length || offset + len > array.length) {
throw new IndexOutOfBoundsException();
}
if (len > 0) {
if (doEncode) {
baseNCodec.encode(array, offset, len, context);
} else {
baseNCodec.decode(array, offset, len, context);
}
flush(false);
}
}
/**
* Writes the specified {@code byte} to this output stream.
*
* @param i source byte.
* @throws IOException if an I/O error occurs.
*/
@Override
public void write(final int i) throws IOException {
singleByte[0] = (byte) i;
write(singleByte, 0, 1);
}
}