FSInputStream.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.fs;
- import java.io.*;
- /****************************************************************
- * FSInputStream is a generic old InputStream with a little bit
- * of RAF-style seek ability.
- *
- *****************************************************************/
- public abstract class FSInputStream extends InputStream
- implements Seekable, PositionedReadable {
- /**
- * Seek to the given offset from the start of the file.
- * The next read() will be from that location. Can't
- * seek past the end of the file.
- */
- public abstract void seek(long pos) throws IOException;
- /**
- * Return the current offset from the start of the file
- */
- public abstract long getPos() throws IOException;
- /**
- * Seeks a different copy of the data. Returns true if
- * found a new source, false otherwise.
- */
- public abstract boolean seekToNewSource(long targetPos) throws IOException;
- public int read(long position, byte[] buffer, int offset, int length)
- throws IOException {
- synchronized (this) {
- long oldPos = getPos();
- int nread = -1;
- try {
- seek(position);
- nread = read(buffer, offset, length);
- } finally {
- seek(oldPos);
- }
- return nread;
- }
- }
-
- public void readFully(long position, byte[] buffer, int offset, int length)
- throws IOException {
- int nread = 0;
- while (nread < length) {
- int nbytes = read(position+nread, buffer, offset+nread, length-nread);
- if (nbytes < 0) {
- throw new EOFException("End of file reached before reading fully.");
- }
- nread += nbytes;
- }
- }
-
- public void readFully(long position, byte[] buffer)
- throws IOException {
- readFully(position, buffer, 0, buffer.length);
- }
- }