Byte-ranging implementation (correct version)

Question

I am trying to implement byte-ranging support for WebLogic 6.0.
          Unfortunately, Acrobat Reader does not understand my http response with
          ranges and crashes (or waits for something forever). Does anybody have any
          idea what might be wrong? See my code below.
          Is there a java servlet already that implements byte-ranging?
          Thank you,
          Andrei
          import java.io.*;
          import java.util.*;
          import javax.servlet.*;
          import javax.servlet.http.*;
          /** For testing only, do not look at it. */
          public class ViewFile extends HttpServlet
          public void service(HttpServletRequest req, HttpServletResponse res) throws
          ServletException, IOException
          System.out.println("ViewFile start at " + new Date());
          // Print the headers
          for (Enumeration e = req.getHeaderNames() ; e.hasMoreElements() ;)
          String name = (String)e.nextElement();
          System.out.println("> " + name + ": " + req.getHeader(name));
          // Get the file to view
          String file = req.getPathTranslated();
          // No file, nothing to view
          if (file == null)
          file = getServletContext().getRealPath("/index.html");
          System.out.println(file);
          // OK. Do the job!
          renderFileWithByteRanging(file, req, res);
          System.out.println("ViewFile finish\n");
          /** Represents a single byte range. */
          class Range
          public Range(long start, long end)
          this.start = start;
          this.end = end;
          /** The start of the range (zero based). */
          public long start;
          /** The end of the range. */
          public long end;
          * Parses the incoming ranges into a list of ranges.
          * @param ranges The string containing the ranges.
          * @param fileLength The length of the file.
          public LinkedList parseRanges(String ranges, long fileLength) throws
          Exception
          // Create an empty range list
          LinkedList result = new LinkedList();
          // Remove the "bytes=" part from the range
          int pos = ranges.indexOf('=');
          if (pos == -1)
          throw new Exception("Malformated range request: no '=' symbol");
          if ("bytes".equalsIgnoreCase(ranges.substring(pos).trim()))
          throw new Exception("Malformated range request: 'bytes'
          expected");
          ranges = ranges.substring(pos + 1);
          // Go through the range string and extract the ranges
          StringTokenizer tok = new StringTokenizer(ranges, ",");
          while (tok.hasMoreTokens())
          // Get the next range
          String rangesPart = tok.nextToken().trim();
          // Find a minus separating the range
          pos = rangesPart.indexOf('-');
          if (pos == -1)
          System.out.println("Malformated range request: no '-' symbol");
          continue;
          String strFirst = rangesPart.substring(0, pos).trim();
          String strLast = rangesPart.substring(pos + 1).trim();
          System.out.println("Parsed range: " + strFirst + "-" + strLast);
          long posFirst;
          long posLast;
          if ("".equals(strFirst)) // The first parameter is missing
          // Last n bytes. Example: -500
          posFirst = fileLength - Integer.parseInt(strLast);
          posLast = fileLength;
          else if ("".equals(strFirst)) // The second parameter is missing
          // All bytes except first n bytes. Example: 500-
          posFirst = Integer.parseInt(strFirst);
          posLast = fileLength;
          else // Full range request
          // All bytes from n to m. Example: 500-600
          posFirst = Integer.parseInt(strFirst);
          posLast = Integer.parseInt(strLast);
          // Final checks
          if (posLast > fileLength)
          posLast = fileLength - 1;
          if (posFirst >= posLast)
          posFirst = 0;
          posLast = fileLength - 1;
          // Add the range to the list
          result.addLast(new Range(posFirst, posLast));
          // That's all
          return result;
          /** Put entire file to the outpt stream. */
          public void renderFile(ServletOutputStream sos, File file) throws
          Exception
          FileInputStream fis = null;
          try
          // Create the input stream
          fis = new FileInputStream(file);
          // Allocate the 4K buffer
          byte[] buffer = new byte[4 * 1024];
          // Copy the input to the output
          int bytesRead;
          while((bytesRead = fis.read(buffer)) != -1)
          sos.write(buffer, 0, bytesRead);
          finally
          if (fis != null)
          fis.close();
          /** Put the range of the file to the output stream. */
          public void renderFileRange(ServletOutputStream sos, File file, Range
          range) throws Exception
          FileInputStream fis = null;
          try
          System.out.print("Serving range: " + range.start + "-" + range.end);
          // Create the input stream
          fis = new FileInputStream(file);
          // Skip the first bytes
          if (range.start > 0)
          long skipped = fis.skip(range.start);
          System.out.print("; skipped=" + skipped);
          // Read the requested bytes
          int rangeLength = (int)(range.end - range.start + 1);
          byte[] buffer = new byte[rangeLength];
          int bytesRead = fis.read(buffer, 0, rangeLength);
          // Write the bytes
          if (bytesRead > 0)
          sos.write(buffer, 0, bytesRead);
          System.out.println("; read=" + bytesRead);
          finally
          if (fis != null)
          fis.close();
          /* Calculate multi part content length. May not work properly. */
          public long calculateContentLength(LinkedList ranges, long fileLength,
          String contentType)
          String str;
          long length = -2;
          String boundary = "multipart-boundary";
          for (Iterator i = ranges.iterator(); i.hasNext();)
          // Get the next range
          Range range = (Range)i.next();
          // Render a new boundary
          str = "--" + boundary +
          "Content-type: " + contentType +
          "Content-range: bytes " + range.start + "-" +
          range.end + "/" + fileLength;
          length += 10 + str.length() + range.end - range.start + 1;
          str = "--" + boundary + "--";
          length += 4 + str.length();
          System.out.println("Multi-range response length: " + length);
          return length;
          * Render the specified file to the output stream.
          * The whole file is rendered in binary mode, no other output is
          allowed.
          * @param fileName The name of the file render.
          public void renderFileWithByteRanging(String fileName,
          HttpServletRequest request, HttpServletResponse response) throws IOException
          System.out.println("Serving the file: " + fileName);
          FileInputStream fis = null;
          try
          // Get the output stream
          ServletOutputStream sos = response.getOutputStream();
          // Get and set the type of the file
          String contentType = getServletContext().getMimeType(fileName);
          System.out.println("Content Type: " + contentType);
          // Open file and its length
          File file = new File(fileName);
          long fileLength = file.length();
          System.out.println("File length: " + fileLength);
          // Get ranges
          String httpRange = request.getHeader("Range");
          // Are ranges requested?
          if (httpRange == null)
          // No ranges needed
          System.out.println("No ranges. Proceed in usual way");
          response.setHeader("Accept-ranges", "bytes");
          response.setContentType(contentType);
          response.setHeader("Content-length",
          String.valueOf(file.length()));
          // Disable all kinds of caching
          // response.setHeader("Cache-Control", "no-store");
          // Render the entire file content
          renderFile(sos, file);
          else
          // Well, ranges.......
          System.out.println("Ranges are requested.");
          LinkedList ranges = parseRanges(httpRange, fileLength);
          Range range;
          // Check if we got a single range request
          if (ranges.size() == 1)
          // Yeah... a single range. Return it in the simple form
          (Apache-style)
          System.out.println("Serving a single range.");
          range = (Range)ranges.getFirst();
          sos.println("Status: 206 Partial content");
          sos.println("Content-range: bytes " + range.start + "-"
          + range.end + "/" + fileLength);
          sos.println("Content-length: " + (range.start -
          range.end + 1));
          sos.println("Content-type: " + contentType);
          sos.println();
          sos.println();
          // Render the range of the file
          renderFileRange(sos, file, range);
          else
          // Well... many ranges. Return a multipart response
          System.out.println("Serving multiple ranges.");
          // Render the multi-parse response header
          String boundary = "multipart-boundary";
          sos.println("Status: 206 Partial content");
          sos.println("Accept-ranges: bytes");
          sos.println("Content-type: multipart/x-byteranges; boundary=" +
          boundary);
          // sos.println("Content-length: " + calculateContentLength(ranges,
          fileLength, contentType));
          sos.println();
          // Go through the range list and return the
          corresponding file bits
          for (Iterator i = ranges.iterator(); i.hasNext();)
          // Get the next range
          range = (Range)i.next();
          // Render a new boundary
          sos.println();
          sos.println("--" + boundary);
          sos.println("Content-type: " + contentType);
          sos.println("Content-range: bytes " + range.start +
          "-" + range.end + "/" + fileLength);
          sos.println();
          // Render the range of the file
          renderFileRange(sos, file, range);
          // Finish the multipart response
          sos.println();
          sos.println("--" + boundary + "--");
          System.out.println("Done Serving");
          catch(FileNotFoundException fnf)
          // Send the file-not-found status if we could not open the file
          response.sendError(response.SC_NOT_FOUND);
          System.out.println("File '" + fileName + "' is not found");
          catch(Exception e)
          // Send the internal-error status for all other reasons
          if (!response.isCommitted())
          response.sendError(response.SC_INTERNAL_SERVER_ERROR,
          e.getMessage());
          e.printStackTrace();
          

Answer 1

First just to clarify EBS is currently using OAF and not ADF.
More info here:
http://blogs.oracle.com/schan/2007/06/28#a1721
OAF uses ADF Business Components - so if you want to use ADF to build a system that will integrate with EBS then it would make sense to go to the "ADF Tutorial for Forms/4GL Developers" tutorial.