com.google.common.io.MultiReader Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* Copyright (C) 2008 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.base.Preconditions;
import java.io.IOException;
import java.io.Reader;
import java.util.Iterator;
import javax.annotation.CheckForNull;
/**
* A {@link Reader} that concatenates multiple readers.
*
* @author Bin Zhu
* @since 1.0
*/
@GwtIncompatible
@ElementTypesAreNonnullByDefault
class MultiReader extends Reader {
private final Iterator it;
@CheckForNull private Reader current;
MultiReader(Iterator readers) throws IOException {
this.it = readers;
advance();
}
/** Closes the current reader and opens the next one, if any. */
private void advance() throws IOException {
close();
if (it.hasNext()) {
current = it.next().openStream();
}
}
@Override
public int read(char[] cbuf, int off, int len) throws IOException {
checkNotNull(cbuf);
if (current == null) {
return -1;
}
int result = current.read(cbuf, off, len);
if (result == -1) {
advance();
return read(cbuf, off, len);
}
return result;
}
@Override
public long skip(long n) throws IOException {
Preconditions.checkArgument(n >= 0, "n is negative");
if (n > 0) {
while (current != null) {
long result = current.skip(n);
if (result > 0) {
return result;
}
advance();
}
}
return 0;
}
@Override
public boolean ready() throws IOException {
return (current != null) && current.ready();
}
@Override
public void close() throws IOException {
if (current != null) {
try {
current.close();
} finally {
current = null;
}
}
}
}