mirror of https://github.com/apache/cloudstack.git
95 lines
2.5 KiB
Java
95 lines
2.5 KiB
Java
// Licensed to the Apache Software Foundation (ASF) under one
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// or more contributor license agreements. See the NOTICE file
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// distributed with this work for additional information
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// regarding copyright ownership. The ASF licenses this file
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// to you under the Apache License, Version 2.0 (the
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// "License"); you may not use this file except in compliance
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// with the License. You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations
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// under the License.
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package com.cloud.bridge.io;
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import java.io.File;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.RandomAccessFile;
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public class FileRangeInputStream extends InputStream {
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private RandomAccessFile randomAccessFile;
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private long curPos;
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private long endPos;
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private long fileLength;
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public FileRangeInputStream(File file, long startPos, long endPos) throws IOException {
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fileLength = file.length();
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if(startPos > fileLength)
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startPos = fileLength;
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if(endPos > fileLength)
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endPos = fileLength;
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if(startPos > endPos)
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throw new IllegalArgumentException("Invalid file range " + startPos + "-" + endPos);
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this.curPos = startPos;
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this.endPos = endPos;
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randomAccessFile = new RandomAccessFile(file, "r");
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randomAccessFile.seek(startPos);
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}
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@Override
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public int available() throws IOException {
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return (int)(endPos - curPos);
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}
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@Override
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public int read() throws IOException {
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if(available() > 0) {
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int value = randomAccessFile.read();
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curPos++;
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return value;
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}
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return -1;
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}
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@Override
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public int read(byte[] b) throws IOException {
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return read(b, 0, b.length);
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}
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@Override
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public int read(byte[] b, int off, int len) throws IOException {
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int bytesToRead = Math.min(len, available());
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if(bytesToRead == 0)
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return -1;
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int bytesRead = randomAccessFile.read(b, off, bytesToRead);
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if(bytesRead < 0)
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return -1;
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curPos += bytesRead;
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return bytesRead;
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}
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@Override
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public long skip(long n) throws IOException {
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long skipped = Math.min(n, available());
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randomAccessFile.skipBytes((int)skipped);
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curPos += skipped;
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return skipped;
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}
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@Override
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public void close() throws IOException {
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randomAccessFile.close();
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}
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}
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