git.gag.com Git - debian/openrocket/blob - src/net/sf/openrocket/file/GeneralRocketLoader.java

   1 package net.sf.openrocket.file;
   2
   3 import java.io.BufferedInputStream;
   4 import java.io.IOException;
   5 import java.io.InputStream;
   6 import java.nio.charset.Charset;
   7 import java.util.zip.GZIPInputStream;
   8
   9 import net.sf.openrocket.document.OpenRocketDocument;
  10 import net.sf.openrocket.file.openrocket.OpenRocketLoader;
  11
  12
  13 /**
  14  * A rocket loader that auto-detects the document type and uses the appropriate
  15  * loading.  Supports loading of GZIPed files as well with transparent
  16  * uncompression.
  17  *
  18  * @author Sampo Niskanen <sampo.niskanen@iki.fi>
  19  */
  20 public class GeneralRocketLoader extends RocketLoader {
  21
  22         private static final int READ_BYTES = 300;
  23
  24         private static final byte[] GZIP_SIGNATURE = { 31, -117 };  // 0x1f, 0x8b
  25         private static final byte[] OPENROCKET_SIGNATURE =
  26                 "<openrocket".getBytes(Charset.forName("US-ASCII"));
  27
  28         private final OpenRocketLoader openRocketLoader = new OpenRocketLoader();
  29
  30         @Override
  31         protected OpenRocketDocument loadFromStream(InputStream source) throws IOException,
  32                         RocketLoadException {
  33
  34                 // Check for mark() support
  35                 if (!source.markSupported()) {
  36                         source = new BufferedInputStream(source);
  37                 }
  38
  39                 // Read using mark()
  40                 byte[] buffer = new byte[READ_BYTES];
  41                 int count;
  42                 source.mark(READ_BYTES + 10);
  43                 count = source.read(buffer);
  44                 source.reset();
  45
  46                 if (count < 10) {
  47                         throw new RocketLoadException("Unsupported or corrupt file.");
  48                 }
  49
  50                 // Detect the appropriate loader
  51
  52                 // Check for GZIP
  53                 if (buffer[0] == GZIP_SIGNATURE[0]  &&  buffer[1] == GZIP_SIGNATURE[1]) {
  54                         OpenRocketDocument doc = loadFromStream(new GZIPInputStream(source));
  55                         doc.getDefaultStorageOptions().setCompressionEnabled(true);
  56                         return doc;
  57                 }
  58
  59                 // Check for OpenRocket
  60                 int match = 0;
  61                 for (int i=0; i < count; i++) {
  62                         if (buffer[i] == OPENROCKET_SIGNATURE[match]) {
  63                                 match++;
  64                                 if (match == OPENROCKET_SIGNATURE.length) {
  65                                         return loadUsing(source, openRocketLoader);
  66                                 }
  67                         } else {
  68                                 match = 0;
  69                         }
  70                 }
  71
  72                 throw new RocketLoadException("Unsupported or corrupt file.");
  73         }
  74
  75         private OpenRocketDocument loadUsing(InputStream source, RocketLoader loader)
  76         throws RocketLoadException {
  77                 warnings.clear();
  78                 OpenRocketDocument doc = loader.load(source);
  79                 warnings.addAll(loader.getWarnings());
  80                 return doc;
  81         }
  82 }