org.apache.commons.io.input.NullInputStream#read ( )源码实例Demo

@Override
public synchronized int read(final byte[] chunk, final Long offset) throws IOException {
    final RandomAccessFile file = random();
    if(offset < file.length()) {
        file.seek(offset);
        if(chunk.length + offset > file.length()) {
            return file.read(chunk, 0, (int) (file.length() - offset));
        }
        else {
            return file.read(chunk, 0, chunk.length);
        }
    }
    else {
        final NullInputStream nullStream = new NullInputStream(length);
        if(nullStream.available() > 0) {
            nullStream.skip(offset);
            return nullStream.read(chunk, 0, chunk.length);
        }
        else {
            return IOUtils.EOF;
        }
    }
}
 

@Test(expected = IOException.class)
public void compute() throws Exception {
    final NullInputStream in = new NullInputStream(0L);
    new DisabledChecksumCompute().compute(in, new TransferStatus());
    assertEquals(-1, in.read());
    in.read();
}