apache-poi/src/java/org/apache/poi/util/BlockingInputStream.java

package org.apache.poi.util;

import java.io.InputStream;
import java.io.IOException;

/**
 * Implementation of a BlockingInputStream to provide data to 
 * RawDataBlock that expects data in 512 byte chunks.  Useful to read
 * data from slow (ie, non FileInputStream) sources, for example when 
 * reading an OLE2 Document over a network. 
 *
 * Possible extentions: add a timeout. Curently a call to read(byte[]) on this
 *    class is blocking, so use at your own peril if your underlying stream blocks. 
 *
 * @author Jens Gerhard
 * @author aviks - documentation cleanups. 
 */
public class BlockingInputStream
      extends InputStream
{
      protected InputStream is;

      public BlockingInputStream(InputStream is)
      {
          this.is = is;
      }

      public int available()
        throws IOException
      {
          return is.available();
      }

      public void close()
        throws IOException
      {
          is.close();
      }

      public void mark(int readLimit)
      {
          is.mark(readLimit);
      }

      public boolean markSupported()
      {
          return is.markSupported();
      }

      public int read()
        throws IOException
      {
          return is.read();
      }
      
      /**
       * We had to revert to byte per byte reading to keep
       * with slow network connections on one hand, without
       * missing the end-of-file. 
       * This is the only method that does its own thing in this class
       *    everything else is delegated to aggregated stream. 
       * THIS IS A BLOCKING BLOCK READ!!!
       */
      public int read(byte[] bf)
        throws IOException
      {
          
          int i = 0;
          int b = 4611;
          while ( i < bf.length )
          {
              b = is.read();
              if ( b == -1 )
                  break;
              bf[i++] = (byte) b;
          }
          if ( i == 0 && b == -1 )
              return -1;
          return i;
      }

      public int read(byte[] bf, int s, int l)
        throws IOException
      {
          return is.read(bf, s, l);
      }

      public void reset()
        throws IOException
      {
          is.reset();
      }

      public long skip(long n)
        throws IOException
      {
          return is.skip(n);
      }
}