92 lines
2.7 KiB
Java
92 lines
2.7 KiB
Java
/*
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* Copyright 2021 Paul Schaub.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package sop.util;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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/**
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* {@link OutputStream} that buffers data being written into it, until its underlying output stream is being replaced.
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* At that point, first all the buffered data is being written to the underlying stream, followed by any successive
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* data that may get written to the {@link ProxyOutputStream}.
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*
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* This class is useful if we need to provide an {@link OutputStream} at one point in time where the final
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* target output stream is not yet known.
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*/
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public class ProxyOutputStream extends OutputStream {
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private final ByteArrayOutputStream buffer;
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private OutputStream swapped;
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public ProxyOutputStream() {
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this.buffer = new ByteArrayOutputStream();
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}
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public synchronized void replaceOutputStream(OutputStream underlying) throws IOException {
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if (underlying == null) {
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throw new NullPointerException("Underlying OutputStream cannot be null.");
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}
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this.swapped = underlying;
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byte[] bufferBytes = buffer.toByteArray();
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swapped.write(bufferBytes);
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}
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@Override
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public synchronized void write(byte[] b) throws IOException {
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if (swapped == null) {
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buffer.write(b);
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} else {
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swapped.write(b);
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}
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}
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@Override
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public synchronized void write(byte[] b, int off, int len) throws IOException {
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if (swapped == null) {
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buffer.write(b, off, len);
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} else {
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swapped.write(b, off, len);
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}
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}
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@Override
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public synchronized void flush() throws IOException {
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buffer.flush();
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if (swapped != null) {
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swapped.flush();
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}
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}
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@Override
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public synchronized void close() throws IOException {
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buffer.close();
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if (swapped != null) {
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swapped.close();
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}
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}
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@Override
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public synchronized void write(int i) throws IOException {
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if (swapped == null) {
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buffer.write(i);
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} else {
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swapped.write(i);
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}
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}
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}
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