utf 8 - Convert a sequence of bytes to a jpeg file in Java -

i interfacing medical instrument pc using java . data transfer working fine. problem along content (string), data contains 4 jpeg images . entire stream encoded in utf-8. problem able extract data jpeg unable save file in right format.

i have looked around , data looks fine (in starts ffd8 , ends ffd9)

i'm storing byte data in array _tmp. have tried following

1) writing bytes file

fileoutputstream _fos = new fileoutputstream(_filename); _fos.write(_image_string.getbytes()); _fos.flush() _fos.close(); 

i following error when try open file

i have tried use bufferedimage follows

bufferedimage _bi = imageio.read(new bytearrayinputstream(_tmp)); file _image = new file(_filename); imageio.write(_bi,"jpg",_image); 

for following exception raised.

java.lang.illegalargumentexception: image == null!   @ javax.imageio.imagetypespecifier.createfromrenderedimage(unknown source)  @ javax.imageio.imageio.getwriter(unknown source) 

the spec of data format pasted below.(even though mentions bmp data - documentation mentions in jpeg format)

i realize has encoding. not able figure out. pointers appreciated.

your jpeg data in string "ffd8ffe0 ....ffd9"?
(no spaces between hex values ff d8 ff e0)? remove whitespace or non-hex chars (valid hex chars : digits "0" "9" , letters "a" "f").

convert string bytes

//# import class import javax.xml.bind.datatypeconverter;  //# declare byte array public static byte[] imagebytes;  //# string imagebytes convert with... (writes byte integers hex values) imagebytes = datatypeconverter.parsehexbinary( my_hex_string ); 

now imagebytes can saved file or used (input) jpeg data in other functions.

some example code :

this should output below valid jpeg string:

byte value 0 : -1 (which == 0xff)
byte value 1 : -40 (which == 0xd8)
byte value 2 : -1 (which == 0xff)
byte value 3 : -32 (which == 0xe0)

package hexstringtobytearray_v1;  import javax.xml.bind.datatypeconverter;  public class hexstringtobytearray_v1  {     public static string image_hexstr = "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    public static byte[] imagebytes;      public static void main(string[] args)      {         //run conversion function (convert hex values in string byte integers)         imagebytes = hexstringtobytearray( image_hexstr );          system.out.println("byte value 0 : "  + imagebytes[0] );         system.out.println("byte value 1 : "  + imagebytes[1] );         system.out.println("byte value 2 : "  + imagebytes[2] );         system.out.println("byte value 3 : "  + imagebytes[3] );     }      public static byte[] hexstringtobytearray(string input)      { return datatypeconverter.parsehexbinary( input ); }  }