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| private boolean isMatch(byte[] pattern, byte[] data) {
if (pattern.length <= data.length) {
for (int idx = 0; idx < pattern.length; ++idx) {
if (pattern[idx] != data[idx])
return false;
}
return true;
}
return false;
}
private String getImageType(byte[] data) {
// filetype magic number(hex)
// jpg FF D8 FF
// gif 47 49 46 38
// png 89 50 4E 47 0D 0A 1A 0A
// bmp 42 4D
// tiff(LE) 49 49 2A 00
// tiff(BE) 4D 4D 00 2A
final byte[] pngPattern = new byte[] { (byte)0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A};
final byte[] jpgPattern = new byte[] { (byte)0xFF, (byte)0xD8, (byte)0xFF};
final byte[] gifPattern = new byte[] { 0x47, 0x49, 0x46, 0x38};
final byte[] bmpPattern = new byte[] { 0x42, 0x4D };
final byte[] tiffLEPattern = new byte[] { 0x49, 0x49, 0x2A, 0x00};
final byte[] tiffBEPattern = new byte[] { 0x4D, 0x4D, 0x00, 0x2A};
if (isMatch(pngPattern, data))
return "image/png";
if (isMatch(jpgPattern, data))
return "image/jpg";
if (isMatch(gifPattern, data))
return "image/gif";
if (isMatch(bmpPattern, data))
return "image/bmp";
if (isMatch(tiffLEPattern, data))
return "image/tif";
if (isMatch(tiffBEPattern, data))
return "image/tif";
return "image/png";
}
String imageDataBytes = base64String.substring(base64String.indexOf(",") + 1);
byte[] bytes = Base64.decodeBase64(imageDataBytes);
String imageMimeType = getImageType(bytes);
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