BinaryReader.java

package sample;

public class BinaryReader {
    enum Endian {
        Little,
        Big
    }
    private Endian endianness;
    public BinaryReader(Endian endian) {
        this.endianness = endian;
    }

    public short bytesToShort(byte[] data, long _offset) {
        int offset = (int) _offset;
        int ret = 0;
        if (endianness == Endian.Little) {
            ret += data[offset];
            ret += data[offset + 1] << 8;
        } else {
            ret += data[offset] << 8;
            ret += data[offset + 1];
        }
        return (short)ret;
    }
    public short bytesToUnsignedShort(byte[] data, long _offset) {
        int offset = (int) _offset;
        long ret = 0;
        if (endianness == Endian.Little) {
            ret += data[offset] & 0xff;
            ret += (data[offset + 1] & 0xff) << 8;
        } else {
            ret += data[offset] & 0xff << 24;
            ret += (data[offset + 1] & 0xff) << 16;
        }
        return (short) ret;
    }
    public long bytesToLong(byte[] data, long _offset) {
        int offset = (int) _offset;
        long ret = 0;
        if (endianness == Endian.Little) {
            ret += data[offset] & 0xff;
            ret += (data[offset + 1] & 0xff) << 8;
            ret += (data[offset + 2] & 0xff) << 16;
            ret += (data[offset + 3] & 0xff) << 24;
        } else {
            ret += data[offset] & 0xff << 24;
            ret += (data[offset + 1] & 0xff) << 16;
            ret += (data[offset + 2] & 0xff) << 8;
            ret += (data[offset + 3] & 0xff);
        }
        return ret;
    }
}

FileReadTest.java

package sample;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;

public class FileReadTest {
    interface IFD_TAG_TYPE {
        int SHORT = 3;
    }
    interface IFD_TAG_ID {
        int WIDTH = 0x0100;
        int HEIGHT = 0x0101;
    }
    public static void main(String[] args) {
        final String fileName = "IMG_2631.CR2";

        File file = new File(fileName);
        ByteBuffer bb = ByteBuffer.allocate((int)file.length());
        try (FileInputStream fis = new FileInputStream(file)) {
            byte[] data = new byte[16];
            fis.read(data, 0, 16);

            BinaryReader binRead;
            if (data[0] == 0x49 && data[0] == data[1]) {
                binRead = new BinaryReader(BinaryReader.Endian.Little);
            } else if (data[0] == 0x4d && data[0] == data[1]) {
                binRead = new BinaryReader(BinaryReader.Endian.Big);
            } else {
                throw new RuntimeException("Could'nt recognize magic");
            }
            short magic = binRead.bytesToShort(data, 0x0002);
            if (magic != 0x002a) {
                throw new RuntimeException("Could'nt recognize magic");
            }

            long tiffOffset = binRead.bytesToLong(data, 0x0004);
            System.out.format("TIFF.offset = 0x%08x\n", tiffOffset);

            short cr2Magic = binRead.bytesToShort(data, 0x0008);
            if (cr2Magic != 0x5243) {
                throw new RuntimeException("Could'nt recognize magic");
            }
            byte cr2MajorVersion = data[0x000a];
            byte cr2minorVersion = data[0x000b];
            System.out.format("CR2.version = %d.%d\n", cr2MajorVersion, cr2minorVersion);
            long ifd3Offset = binRead.bytesToLong(data, 0x000c);
            System.out.format("IFD3.offset = %08x\n", ifd3Offset);

            bb.put(data);

            while (true) {
                byte[] temp = new byte[100000];
                int length = fis.read(temp, 0, temp.length);
                if (length <= 0) {
                    break;
                }
                bb.put(temp, 0, length);
            }

            System.out.println(" -- IFD0 --");

            byte[] allData = bb.array();

            short numberOfEntries = binRead.bytesToShort(allData, tiffOffset);
            System.out.format("numberOfEntries=%04x\n", numberOfEntries);
            for (int i = 0;i < numberOfEntries;i++) {
                long offset = tiffOffset + i * 12 + 2;
                short tagId = binRead.bytesToShort(allData, offset);
                short tagType = binRead.bytesToShort(allData, offset + 2);
                long tagValue = 0;
                if (tagType == IFD_TAG_TYPE.SHORT) {
                    tagValue = binRead.bytesToUnsignedShort(allData, offset + 4);
                }
                long tagData = 0;

                if (tagType == IFD_TAG_TYPE.SHORT) {
                    tagData = binRead.bytesToUnsignedShort(allData, offset + 8);
                }
                if (tagId == IFD_TAG_ID.WIDTH) {
                    System.out.format("ifd0.width=%d\n", tagData);
                } else if (tagId == IFD_TAG_ID.HEIGHT) {
                    System.out.format("ifd0.height=%d\n", tagData);
                }
//                System.out.format("tagId=%04x tagType=%d tagValue=%d tagData=%d\n", tagId, tagType, tagValue, tagData);

            }



            System.out.println(" -- IFD3 --");
            short tagId = binRead.bytesToShort(allData, ifd3Offset);
            short tagType = binRead.bytesToShort(allData, ifd3Offset + 2);
            long tagNumber = binRead.bytesToLong(allData, ifd3Offset + 4);
            long nextPointer = binRead.bytesToLong(allData, ifd3Offset + 8);
            System.out.format("tagId=%04x\n", tagId);
            System.out.format("tagType=%04x\n", tagType);
            System.out.format("tagNumber=%08x\n", tagNumber);
            System.out.format("nextPointer=%08x\n", nextPointer);


        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}