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