SphereParser with method to extract xml from image

app/src/main/java/de/trac/spherical/parser/SphereParser.java

@@ -0,0 +1,130 @@
+package de.trac.spherical.parser;
+
+import android.util.Log;
+
+import java.io.EOFException;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.PushbackInputStream;
+import java.math.BigInteger;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+/**
+ * Created by vanitas on 12.09.17.
+ */
+
+@SuppressWarnings("ResultOfMethodCallIgnored")
+public class SphereParser {
+
+    public static final String TAG = "SphereParser";
+
+    public static final String USE_PANORAMA_VIEWER = "GPano:UsePanoramaViewer=\"True\"";
+
+    /*
+     * 0    FF
+     * 1    D8
+     * 2    FF
+     * 3    E1
+     * 4    Length EXIF (n)
+     * 5    Length EXIF (n)
+     * 6    <exif>
+     * n+4  </exif>
+     * n+5  FF
+     * n+6  E1
+     * n+7  Length XML (m)
+     * n+7  Length XML (m)
+     * n+8  <xml>
+     * n+8+m</xml>
+     * n+5  <xml>
+     * ?    </xml>
+     */
+
+    public static final byte[] FFE1 = new byte[] {
+            (byte) 0xFF, (byte) 0xE1
+    };
+
+    public static final byte[] FFD8FFE1 = new byte[] {
+            (byte) 0xFF, (byte) 0xD8, (byte) 0xFF, (byte) 0xE1
+    };
+
+
+
+    public static String getXMLContent(InputStream inputStream) throws IOException {
+        if (inputStream == null) {
+            throw new IllegalArgumentException("File MUST NOT be null!");
+        }
+
+        //HEADER
+        byte[] r = new byte[FFD8FFE1.length];
+        int i = inputStream.read(r);
+        if (i != FFD8FFE1.length || !Arrays.equals(FFD8FFE1, r)) {
+            System.out.println("Unexpected Image header: " + hex(r) + " (" + hex(FFD8FFE1) + " expected)");
+            return null;
+        }
+
+        //EXIF Length
+        r = new byte[2];
+        i = inputStream.read(r);
+        if (i != 2) {
+            throw new EOFException("Unexpected EOF!");
+        }
+        int exifLen = integer(r);
+
+        //Skip EXIF header
+        r = new byte[exifLen - 2];
+        i = inputStream.read(r);
+
+        //XML Header
+        r = new byte[2];
+        i = inputStream.read(r);
+        if (!Arrays.equals(FFE1, r)) {
+            System.out.println("Image does not contain XML data.");
+            return null;
+        }
+
+        r = new byte[2];
+        i = inputStream.read(r);
+        if (i != 2) {
+            throw new EOFException("Unexpected EOF!");
+        }
+        int xmlLen = integer(r);
+
+        byte[] xml = new byte[xmlLen - 2];
+        i = inputStream.read(xml);
+        if (i != xml.length) {
+            throw new EOFException("Unexpected EOF!");
+        }
+
+        return new String(xml);
+    }
+
+    public static void main(String[] args) throws IOException {
+        File file = new File(args[0]);
+        System.out.println(getXMLContent(new FileInputStream(file)));
+    }
+
+    public static void unread(ArrayList<Byte> list, PushbackInputStream pb) throws IOException {
+        for (int i = list.size() - 1; i >= 0; i--) {
+            pb.unread(list.get(i));
+        }
+    }
+
+    public static void append(ArrayList<Byte> list, byte[] array, int r) {
+        for (int i = 0; i < r; i++) {
+            list.add(array[i]);
+        }
+    }
+
+    public static String hex(byte[] b) {
+        return new BigInteger(b).toString(16);
+    }
+
+    public static int integer(byte[] b) {
+        return new BigInteger(b).intValue();
+    }
+}