124 lines
2.5 KiB
Java
124 lines
2.5 KiB
Java
/*
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* Copyright (C) 2007 The Guava Authors
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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 com.google.common.io;
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import static com.google.common.base.Preconditions.checkNotNull;
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import java.io.IOException;
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import java.io.InputStream;
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import java.util.Iterator;
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import javax.annotation.Nullable;
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/**
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* An {@link InputStream} that concatenates multiple substreams. At most one
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* stream will be open at a time.
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*
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* @author Chris Nokleberg
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* @since 1.0
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*/
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final class MultiInputStream extends InputStream {
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private Iterator<? extends ByteSource> it;
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private InputStream in;
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/**
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* Creates a new instance.
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*
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* @param it an iterator of I/O suppliers that will provide each substream
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*/
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public MultiInputStream(Iterator<? extends ByteSource> it) throws IOException {
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this.it = checkNotNull(it);
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advance();
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}
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@Override
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public void close() throws IOException {
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if (in != null) {
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try {
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in.close();
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} finally {
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in = null;
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}
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}
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}
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/**
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* Closes the current input stream and opens the next one, if any.
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*/
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private void advance() throws IOException {
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close();
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if (it.hasNext()) {
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in = it.next().openStream();
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}
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}
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@Override
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public int available() throws IOException {
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if (in == null) {
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return 0;
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}
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return in.available();
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}
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@Override
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public boolean markSupported() {
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return false;
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}
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@Override
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public int read() throws IOException {
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if (in == null) {
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return -1;
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}
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int result = in.read();
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if (result == -1) {
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advance();
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return read();
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}
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return result;
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}
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@Override
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public int read(@Nullable byte[] b, int off, int len) throws IOException {
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if (in == null) {
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return -1;
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}
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int result = in.read(b, off, len);
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if (result == -1) {
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advance();
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return read(b, off, len);
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}
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return result;
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}
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@Override
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public long skip(long n) throws IOException {
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if (in == null || n <= 0) {
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return 0;
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}
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long result = in.skip(n);
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if (result != 0) {
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return result;
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}
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if (read() == -1) {
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return 0;
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}
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return 1 + in.skip(n - 1);
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}
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}
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