public class FileType {

	private final static Map<String, String> FILE_TYPE_MAP = new HashMap<String, String>();
	
	private FileType(){}
	
	static{
		getAllFileType();  //初始化檔案型別資訊
	}
		
	private static void getAllFileType(){
		FILE_TYPE_MAP.put("ffd8ffe000104a464946", "jpg");
        FILE_TYPE_MAP.put("89504e470d0a1a0a0000", "png");
        FILE_TYPE_MAP.put("47494638396126026f01", "gif");
        FILE_TYPE_MAP.put("49492a00227105008037", "tif");
        FILE_TYPE_MAP.put("424d228c010000000000", "bmp"); // 16色點陣圖(bmp)
        FILE_TYPE_MAP.put("424d8240090000000000", "bmp"); // 24位點陣圖(bmp)
        FILE_TYPE_MAP.put("424d8e1b030000000000", "bmp"); // 256色點陣圖(bmp)
        FILE_TYPE_MAP.put("41433130313500000000", "dwg");
        FILE_TYPE_MAP.put("3c21444f435459504520", "html");
        FILE_TYPE_MAP.put("3c21646f637479706520", "htm");
        FILE_TYPE_MAP.put("48544d4c207b0d0a0942", "css");
        FILE_TYPE_MAP.put("696b2e71623d696b2e71", "js");
        FILE_TYPE_MAP.put("7b5c727466315c616e73", "rtf");
        FILE_TYPE_MAP.put("38425053000100000000", "psd");
        FILE_TYPE_MAP.put("46726f6d3a203d3f6762", "eml");
        FILE_TYPE_MAP.put("d0cf11e0a1b11ae10000", "doc"); // MS Excel、Word、Msi 
        FILE_TYPE_MAP.put("d0cf11e0a1b11ae10000", "vsd");
        FILE_TYPE_MAP.put("5374616E64617264204A", "mdb");
        FILE_TYPE_MAP.put("255044462d312e350d0a", "pdf");
        FILE_TYPE_MAP.put("2e524d46000000120001", "rmvb"); // rmvb、rm
        FILE_TYPE_MAP.put("464c5601050000000900", "flv"); // flv、f4v
        FILE_TYPE_MAP.put("00000020667479706d70", "mp4");  
        FILE_TYPE_MAP.put("49443303000000002176", "mp3");  
        FILE_TYPE_MAP.put("000001ba210001000180", "mpg");
        FILE_TYPE_MAP.put("3026b2758e66cf11a6d9", "wmv"); // wmv、asf
        FILE_TYPE_MAP.put("52494646e27807005741", "wav");
        FILE_TYPE_MAP.put("52494646d07d60074156", "avi");
        FILE_TYPE_MAP.put("4d546864000000060001", "mid");
        FILE_TYPE_MAP.put("504b0304140000000800", "zip");  
        FILE_TYPE_MAP.put("526172211a0700cf9073", "rar");  
        FILE_TYPE_MAP.put("235468697320636f6e66", "ini");  
        FILE_TYPE_MAP.put("504b03040a0000000000", "jar");  
        FILE_TYPE_MAP.put("4d5a9000030000000400", "exe");
        FILE_TYPE_MAP.put("3c25402070616765206c", "jsp");
        FILE_TYPE_MAP.put("4d616e69666573742d56", "mf");
        FILE_TYPE_MAP.put("3c3f786d6c2076657273", "xml");
        FILE_TYPE_MAP.put("494e5345525420494e54", "sql");
        FILE_TYPE_MAP.put("7061636b616765207765", "java");
        FILE_TYPE_MAP.put("406563686f206f66660d", "bat");
        FILE_TYPE_MAP.put("1f8b0800000000000000", "gz");
        FILE_TYPE_MAP.put("6c6f67346a2e726f6f74", "properties");
        FILE_TYPE_MAP.put("cafebabe0000002e0041", "class");
        FILE_TYPE_MAP.put("49545346030000006000", "chm");
        FILE_TYPE_MAP.put("04000000010000001300", "mxp");
        FILE_TYPE_MAP.put("504b0304140006000800", "docx");
        FILE_TYPE_MAP.put("d0cf11e0a1b11ae10000", "wps");// WPS(wps、et、dps)
        FILE_TYPE_MAP.put("6431303a637265617465", "torrent");
        FILE_TYPE_MAP.put("6D6F6F76", "mov");
        FILE_TYPE_MAP.put("FF575043", "wpd");
        FILE_TYPE_MAP.put("CFAD12FEC5FD746F", "dbx");
        FILE_TYPE_MAP.put("2142444E", "pst");
        FILE_TYPE_MAP.put("AC9EBD8F", "qdf");
        FILE_TYPE_MAP.put("E3828596", "pwl");
        FILE_TYPE_MAP.put("2E7261FD", "ram");
	}

	/** 
     * 得到上傳檔案的檔案頭 
     * @param src 
     * @return 
     */  
    private static String bytesToHexString(byte[] src){  
        StringBuilder stringBuilder = new StringBuilder();  
        if(null==src || src.length <= 0){  
            return null;  
        }
        for(int i = 0; i < src.length; i++){  
            int v = src[i] & 0xFF;  
            String hv = Integer.toHexString(v);  
            if(hv.length() < 2){  
                stringBuilder.append(0);  
            }  
            stringBuilder.append(hv);  
        }  
        return stringBuilder.toString();
    }  
	
	/**
	 * 獲取檔案型別
	 * @param file
	 * @return
	 */
	public static String getFileType(File file){
        String res = null;
        try{
            @SuppressWarnings("resource")
			FileInputStream fis = new FileInputStream(file);
            byte[] b = new byte[10];
            fis.read(b, 0, b.length);
            String fileCode = bytesToHexString(b);
                      
            Iterator<String> keyIter = FILE_TYPE_MAP.keySet().iterator();
            while(keyIter.hasNext()){
                String key = keyIter.next();
                if(key.toLowerCase().startsWith(fileCode.toLowerCase()) || fileCode.toLowerCase().startsWith(key.toLowerCase())){
                    res = FILE_TYPE_MAP.get(key);
                    break;
                }
            }
        }catch(FileNotFoundException e){
            e.printStackTrace();  
        }catch (IOException e){
            e.printStackTrace();  
        }  
        return res;
    }
	
}