Java tutorial
/** * Copyright 2011-2017 Asakusa Framework Team. * * 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.asakusafw.runtime.io.sequencefile; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.text.MessageFormat; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FSDataInputStream; import org.apache.hadoop.fs.FSDataOutputStream; import org.apache.hadoop.fs.FileStatus; import org.apache.hadoop.fs.PositionedReadable; import org.apache.hadoop.fs.Seekable; import org.apache.hadoop.io.SequenceFile; import org.apache.hadoop.io.SequenceFile.CompressionType; import org.apache.hadoop.io.compress.CompressionCodec; /** * Accessors for {@link SequenceFile}. * @since 0.2.5 */ public final class SequenceFileUtil { static final Log LOG = LogFactory.getLog(SequenceFileUtil.class); private SequenceFileUtil() { return; } /** * Creates a new reader. * @param in the source * @param status target file status * @param conf current configuration * @return the created sequence file reader * @throws IOException if failed to open the sequence file * @throws IllegalArgumentException if some parameters were {@code null} */ public static SequenceFile.Reader openReader(InputStream in, FileStatus status, Configuration conf) throws IOException { if (in == null) { throw new IllegalArgumentException("in must not be null"); //$NON-NLS-1$ } if (status == null) { throw new IllegalArgumentException("status must not be null"); //$NON-NLS-1$ } if (conf == null) { throw new IllegalArgumentException("conf must not be null"); //$NON-NLS-1$ } if (LOG.isDebugEnabled()) { LOG.debug(MessageFormat.format("Creating sequence file reader for {0}", //$NON-NLS-1$ status.getPath())); } return new SequenceFile.Reader(conf, SequenceFile.Reader.stream(new FSDataInputStream(new WrappedInputStream(in))), SequenceFile.Reader.length(status.getLen())); } /** * Creates a new reader. * @param in the source * @param length the stream length * @param conf current configuration * @return the created sequence file reader * @throws IOException if failed to open the sequence file * @throws IllegalArgumentException if some parameters were {@code null} */ public static SequenceFile.Reader openReader(InputStream in, long length, Configuration conf) throws IOException { if (in == null) { throw new IllegalArgumentException("in must not be null"); //$NON-NLS-1$ } if (conf == null) { throw new IllegalArgumentException("conf must not be null"); //$NON-NLS-1$ } return new SequenceFile.Reader(conf, SequenceFile.Reader.stream(new FSDataInputStream(new WrappedInputStream(in))), SequenceFile.Reader.length(length)); } /** * Creates a new writer. * @param out the drain * @param conf current configuration * @param keyClass the key type * @param valueClass the value type * @param codec the compression codec to block compression, or {@code null} to uncompressed * @return the created sequence file writer * @throws IOException if failed to create a sequence file * @throws IllegalArgumentException if some parameters were {@code null} */ public static SequenceFile.Writer openWriter(OutputStream out, Configuration conf, Class<?> keyClass, Class<?> valueClass, CompressionCodec codec) throws IOException { if (out == null) { throw new IllegalArgumentException("out must not be null"); //$NON-NLS-1$ } if (conf == null) { throw new IllegalArgumentException("conf must not be null"); //$NON-NLS-1$ } if (keyClass == null) { throw new IllegalArgumentException("keyClass must not be null"); //$NON-NLS-1$ } if (valueClass == null) { throw new IllegalArgumentException("valueClass must not be null"); //$NON-NLS-1$ } if (LOG.isDebugEnabled()) { LOG.debug(MessageFormat.format("Creating sequence file writer for output (key={0}, value={0})", //$NON-NLS-1$ keyClass.getName(), valueClass.getName())); } return SequenceFile.createWriter(conf, SequenceFile.Writer.stream(new FSDataOutputStream(out, null)), SequenceFile.Writer.keyClass(keyClass), SequenceFile.Writer.valueClass(valueClass), SequenceFile.Writer.compression(codec == null ? CompressionType.NONE : CompressionType.BLOCK, codec)); } private static class WrappedInputStream extends InputStream implements Seekable, PositionedReadable { private final InputStream input; private long current; WrappedInputStream(InputStream input) { assert input != null; this.input = input; this.current = 0L; } @Override public int read(long position, byte[] buffer, int offset, int length) throws IOException { throw new UnsupportedOperationException(); } @Override public void readFully(long position, byte[] buffer, int offset, int length) throws IOException { throw new UnsupportedOperationException(); } @Override public void readFully(long position, byte[] buffer) throws IOException { throw new UnsupportedOperationException(); } @Override public void seek(long pos) throws IOException { if (pos < current) { throw new UnsupportedOperationException(); } while (pos > current) { skip0(pos - current); } } @Override public long getPos() throws IOException { return current; } @Override public boolean seekToNewSource(long targetPos) throws IOException { return false; } @Override public int read() throws IOException { int result = input.read(); if (result >= 0) { current++; } return result; } @Override public int read(byte[] b) throws IOException { int result = input.read(b); if (result >= 0) { current += result; } return result; } @Override public int read(byte[] b, int off, int len) throws IOException { int result = input.read(b, off, len); if (result >= 0) { current += result; } return result; } @Override public long skip(long n) throws IOException { return skip0(n); } private long skip0(long n) throws IOException { long result = input.skip(n); if (result >= 0) { current += result; } return result; } @Override public int available() throws IOException { return input.available(); } @Override public void close() throws IOException { input.close(); } @Override public boolean markSupported() { return false; } @Override public synchronized void mark(int readlimit) { throw new UnsupportedOperationException(); } @Override public synchronized void reset() throws IOException { throw new UnsupportedOperationException(); } } }