com.google.common.io.MultiInputStream Maven / Gradle / Ivy
/*
* Copyright (C) 2007 The Guava Authors
*
* 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 com.google.common.io;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import javax.annotation.CheckForNull;
/**
* An {@link InputStream} that concatenates multiple substreams. At most one stream will be open at
* a time.
*
* @author Chris Nokleberg
* @since 1.0
*/
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault
final class MultiInputStream extends InputStream {
private Iterator it;
@CheckForNull private InputStream in;
/**
* Creates a new instance.
*
* @param it an iterator of I/O suppliers that will provide each substream
*/
public MultiInputStream(Iterator it) throws IOException {
this.it = checkNotNull(it);
advance();
}
@Override
public void close() throws IOException {
if (in != null) {
try {
in.close();
} finally {
in = null;
}
}
}
/** Closes the current input stream and opens the next one, if any. */
private void advance() throws IOException {
close();
if (it.hasNext()) {
in = it.next().openStream();
}
}
@Override
public int available() throws IOException {
if (in == null) {
return 0;
}
return in.available();
}
@Override
public boolean markSupported() {
return false;
}
@Override
public int read() throws IOException {
while (in != null) {
int result = in.read();
if (result != -1) {
return result;
}
advance();
}
return -1;
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
checkNotNull(b);
while (in != null) {
int result = in.read(b, off, len);
if (result != -1) {
return result;
}
advance();
}
return -1;
}
@Override
public long skip(long n) throws IOException {
if (in == null || n <= 0) {
return 0;
}
long result = in.skip(n);
if (result != 0) {
return result;
}
if (read() == -1) {
return 0;
}
return 1 + in.skip(n - 1);
}
}