package kingsy101;import java.io.FilterInputStream;import java.io.IOException;import java.io.InputStream;public class BlockInputStream extends FilterInputStream { public BlockInputStream (InputStream in, int blockSize) { super (in); if (blockSize <= 0) throw new IllegalArgumentException ("blockSize"); this.blockSize = blockSize; } /** * Reads one block out of the underlying input source. If the source ends * before a complete block can be read, the returned block will be shorter * than the block size; otherwise, this will read until a complete block is * read or the input source fails. * * @return the read block. * @throws IOException * if the input source fails. */ public byte[] readBlock () throws IOException { byte[] buffer = new byte[blockSize]; int totalRead = 0; while (totalRead < blockSize) { int read = in.read (buffer, totalRead, blockSize - totalRead); if (read == -1) return truncateBlock (buffer, totalRead); totalRead += read; } return buffer; } private byte[] truncateBlock (byte[] buffer, int totalRead) { byte[] truncatedBuffer = new byte[totalRead]; System.arraycopy (buffer, 0, truncatedBuffer, 0, totalRead); return truncatedBuffer; } private final int blockSize;}