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