+++ /dev/null
-package tim.prune.jpeg.drew;\r
-\r
-import java.io.*;\r
-\r
-/**\r
- * Class to perform read functions of Jpeg files, returning specific file segments\r
- * Based on Drew Noakes' Metadata extractor at http://drewnoakes.com\r
- */\r
-public class JpegSegmentReader\r
-{\r
- /** Start of scan marker */\r
- private static final byte SEGMENT_SOS = (byte)0xDA;\r
-\r
- /** End of image marker */\r
- private static final byte MARKER_EOI = (byte)0xD9;\r
-\r
- /** APP1 Jpeg segment identifier -- where Exif data is kept. */\r
- private static final byte SEGMENT_APP1 = (byte)0xE1;\r
-\r
- /** Magic numbers to mark the beginning of all Jpegs */\r
- private static final int MAGIC_JPEG_BYTE_1 = 0xFF;\r
- private static final int MAGIC_JPEG_BYTE_2 = 0xD8;\r
-\r
-\r
- /**\r
- * Get the Exif data segment for the specified file\r
- * @param inFile File to read\r
- * @return Exif data segment as byte array\r
- * @throws JpegException on file read errors or exif data errors\r
- */\r
- public static byte[] readExifSegment(File inFile) throws JpegException\r
- {\r
- JpegSegmentData data = readSegments(inFile);\r
- return data.getSegment(SEGMENT_APP1);\r
- }\r
-\r
-\r
- /**\r
- * Obtain the Jpeg segment data from the specified file\r
- * @param inFile File to read\r
- * @return Jpeg segment data from file\r
- * @throws JpegException on file read errors or exif data errors\r
- */\r
- private static JpegSegmentData readSegments(File inFile) throws JpegException\r
- {\r
- JpegSegmentData segmentData = new JpegSegmentData();\r
- BufferedInputStream bStream = null;\r
-\r
- try\r
- {\r
- bStream = new BufferedInputStream(new FileInputStream(inFile));\r
- // first two bytes should be jpeg magic number\r
- final int magic1 = bStream.read() & 0xFF;\r
- final int magic2 = bStream.read() & 0xFF;\r
- if (magic1 != MAGIC_JPEG_BYTE_1 || magic2 != MAGIC_JPEG_BYTE_2) {\r
- throw new JpegException("not a jpeg file");\r
- }\r
-\r
- // Loop around segments found\r
- boolean foundExif = false;\r
- do\r
- {\r
- // next byte is 0xFF\r
- byte segmentIdentifier = (byte) (bStream.read() & 0xFF);\r
- if ((segmentIdentifier & 0xFF) != 0xFF)\r
- {\r
- throw new JpegException("expected jpeg segment start 0xFF, not 0x"\r
- + Integer.toHexString(segmentIdentifier & 0xFF));\r
- }\r
- // next byte is <segment-marker>\r
- byte thisSegmentMarker = (byte) (bStream.read() & 0xFF);\r
- // next 2-bytes are <segment-size>: [high-byte] [low-byte]\r
- byte[] segmentLengthBytes = new byte[2];\r
- bStream.read(segmentLengthBytes, 0, 2);\r
- int segmentLength = ((segmentLengthBytes[0] << 8) & 0xFF00) | (segmentLengthBytes[1] & 0xFF);\r
- // segment length includes size bytes, so subtract two\r
- segmentLength -= 2;\r
- if (segmentLength > bStream.available())\r
- throw new JpegException("segment size would extend beyond file stream length");\r
- else if (segmentLength < 0)\r
- throw new JpegException("segment size would be less than zero");\r
- byte[] segmentBytes = new byte[segmentLength];\r
- int bytesRead = bStream.read(segmentBytes, 0, segmentLength);\r
- // Bail if not all bytes read in one go - otherwise following sections will be out of step\r
- if (bytesRead != segmentLength) {\r
- throw new JpegException("Tried to read " + segmentLength + " bytes but only got " + bytesRead);\r
- }\r
- if ((thisSegmentMarker & 0xFF) == (SEGMENT_SOS & 0xFF))\r
- {\r
- // The 'Start-Of-Scan' segment comes last so break out of loop\r
- break;\r
- }\r
- else if ((thisSegmentMarker & 0xFF) == (MARKER_EOI & 0xFF))\r
- {\r
- // the 'End-Of-Image' segment - should already have exited by now\r
- break;\r
- }\r
- else\r
- {\r
- segmentData.addSegment(thisSegmentMarker, segmentBytes);\r
- }\r
- // loop through to the next segment if exif hasn't already been found\r
- foundExif = (thisSegmentMarker == SEGMENT_APP1);\r
- }\r
- while (!foundExif);\r
- }\r
- catch (FileNotFoundException fnfe)\r
- {\r
- throw new JpegException("Jpeg file not found");\r
- }\r
- catch (IOException ioe)\r
- {\r
- throw new JpegException("IOException processing Jpeg file: " + ioe.getMessage(), ioe);\r
- }\r
- finally\r
- {\r
- try\r
- {\r
- if (bStream != null) {\r
- bStream.close();\r
- }\r
- }\r
- catch (IOException ioe) {\r
- throw new JpegException("IOException processing Jpeg file: " + ioe.getMessage(), ioe);\r
- }\r
- }\r
- // Return the result\r
- return segmentData;\r
- }\r
-}\r