Java determines file type (suffix name) based on file stream

ImportJava.io.FileInputStream; Public classfiletype{ Public StaticString bytestohexstring (byte[] src) {StringBuilder StringBuilder=NewStringBuilder (); if(src = =NULL|| Src.length <= 0) {            return NULL; }         for(inti = 0; i < src.length; i++) {            intv = src[i] & 0xFF; String HV=integer.tohexstring (v); if(Hv.length () < 2) {stringbuilder.append (0);        } stringbuilder.append (HV); }        returnstringbuilder.tostring (); }    /**     * @paramargs*/     Public Static voidMain (string[] args)throwsException {FileInputStream is=NewFileInputStream ("f:\\ album \ \ Picture \\03.jpg"); byte[] B =New byte[3]; Is.read (b,0, b.length); String XXX=bytestohexstring (b); XXX=xxx.touppercase (); System.out.println ("Header file is:" +xxx); String ooo=typedict.checktype (XXX); System.out.println (The suffix name is: "+ooo); }    }

 Public classtypedict {/** File headers for common files are as follows: (previous six-digit) JPEG (jpg), file header: ffd8ff png (PNG), file header: 89504E47 gif (GIF), file header: 47494638 TIFF (TIF), file header: 49492a00 Windows  Bitmap (BMP), file header: 424D CAD (DWG), file header: 41433130 Adobe Photoshop (PSD), file header: 38425053 rich Text Format (RTF), file header: 7b5c727466 XML (XML), file header: 3c3f786d6c HTML (HTML), file header: 68746d6c3e Email [Thorough only] (EML), file header: 44656c69766572792d646174653a Outlook Express (DBX), file header: cfad12fec5fd746f Outlook (PST), file header: 2142444E Ms Word/excel (xls.or.doc), file header: d0cf11e0 Ms Access (MDB), File header: 5374616e64617264204a WordPerfect (WPD), file header: FF575043 Postscript (eps.or.ps), file header: 252150532d41646f6265 Adobe Acrobat (pdf), file header: 255044462d312e Quicken (QDF), file header: ac9ebd8f Windows Password (PWL), file header: E3828596 zip Archive (Zip), File header: 504b0304 rar Archive (RAR), file header: 52617221 Wave (WAV), file header: 57415645 avi (AVI), file header: 41564920 Real Audio (RAM), file header: 2E7261FD Real Media (RM), file header: 2e524d46 MPEG (MPG), file header: 000001BA MPEG (MPG), file header: 000001b3 Quicktime (mov), file header: 6d6f6f76 Windows Media (  ASF), file header: 3026b2758e66cf11 MIDI (mid), file header: 4d546864*/     Public Staticstring Checktype (string xxxx) {Switch(xxxx) { Case"FFD8FF":return"JPG";  Case"89504E":return"PNG";  Case"474946":return"Jif"; default:return"0000"; }    }}

Java determines file type (suffix name) based on file stream