Added new class per bug 13478, to read data from low performance input streams.

Patch submitted by Jens Gerhard - thanks.


git-svn-id: https://svn.apache.org/repos/asf/jakarta/poi/trunk@353030 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -0,0 +1,100 @@
+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);
+      }
+}
+