IFileOutputStream.java
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上传日期:2018-01-08
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文件大小:3k
- /*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements. See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership. The ASF licenses this file
- * to you 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 org.apache.hadoop.mapred;
- import java.io.IOException;
- import java.io.OutputStream;
- import java.io.FilterOutputStream;
- import org.apache.hadoop.util.DataChecksum;
- /**
- * A Checksum output stream.
- * Checksum for the contents of the file is calculated and
- * appended to the end of the file on close of the stream.
- * Used for IFiles
- */
- class IFileOutputStream extends FilterOutputStream {
- /**
- * The output stream to be checksummed.
- */
- private final DataChecksum sum;
- private byte[] barray;
- private boolean closed = false;
- private boolean finished = false;
- /**
- * Create a checksum output stream that writes
- * the bytes to the given stream.
- * @param out
- */
- public IFileOutputStream(OutputStream out) {
- super(out);
- sum = DataChecksum.newDataChecksum(DataChecksum.CHECKSUM_CRC32,
- Integer.MAX_VALUE);
- barray = new byte[sum.getChecksumSize()];
- }
-
- @Override
- public void close() throws IOException {
- if (closed) {
- return;
- }
- closed = true;
- finish();
- out.close();
- }
- /**
- * Finishes writing data to the output stream, by writing
- * the checksum bytes to the end. The underlying stream is not closed.
- * @throws IOException
- */
- public void finish() throws IOException {
- if (finished) {
- return;
- }
- finished = true;
- sum.writeValue(barray, 0, false);
- out.write (barray, 0, sum.getChecksumSize());
- out.flush();
- }
- /**
- * Write bytes to the stream.
- */
- @Override
- public void write(byte[] b, int off, int len) throws IOException {
- sum.update(b, off,len);
- out.write(b,off,len);
- }
-
- @Override
- public void write(int b) throws IOException {
- barray[0] = (byte) (b & 0xFF);
- write(barray,0,1);
- }
- }