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java根據檔案流判斷檔案型別

原文https://www.cnblogs.com/chenglc/p/7117847.html
import java.io.FileInputStream;

public class FileType{
    public static String bytesToHexString(byte[] src) {
        StringBuilder stringBuilder = new StringBuilder();
        if (src == null || 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(); }
/** * @param args */ public static void main(String[] args) throws Exception { FileInputStream is = new FileInputStream("F:\\相簿\\微信圖片\\03.jpg"); byte[] b = new byte[3]; is.read(b, 0, b.length); String xxx = bytesToHexString(b); xxx = xxx.toUpperCase(); System.out.println(
"標頭檔案是:" + xxx); String ooo = TypeDict.checkType(xxx); System.out.println("字尾名是:" + ooo); } }
public class TypeDict {
/**
 常用檔案的檔案頭如下:(以前六位為準)
JPEG (jpg),檔案頭:FFD8FF 
PNG (png),檔案頭:89504E47 
GIF (gif),檔案頭:47494638 
TIFF (tif),檔案頭:49492A00 
Windows Bitmap (bmp),檔案頭:424D 
CAD (dwg),檔案頭:41433130 
Adobe Photoshop (psd),檔案頭:38425053 
Rich Text Format (rtf),檔案頭:7B5C727466 
XML (xml),檔案頭:3C3F786D6C 
HTML (html),檔案頭:68746D6C3E 
Email [thorough only] (eml),檔案頭:44656C69766572792D646174653A 
Outlook Express (dbx),檔案頭:CFAD12FEC5FD746F 
Outlook (pst),檔案頭:2142444E 
MS Word/Excel (xls.or.doc),檔案頭:D0CF11E0 
MS Access (mdb),檔案頭:5374616E64617264204A 
WordPerfect (wpd),檔案頭:FF575043 
Postscript (eps.or.ps),檔案頭:252150532D41646F6265 
Adobe Acrobat (pdf),檔案頭:255044462D312E 
Quicken (qdf),檔案頭:AC9EBD8F 
Windows Password (pwl),檔案頭:E3828596 
ZIP Archive (zip),檔案頭:504B0304 
RAR Archive (rar),檔案頭:52617221 
Wave (wav),檔案頭:57415645 
AVI (avi),檔案頭:41564920 
Real Audio (ram),檔案頭:2E7261FD 
Real Media (rm),檔案頭:2E524D46 
MPEG (mpg),檔案頭:000001BA 
MPEG (mpg),檔案頭:000001B3 
Quicktime (mov),檔案頭:6D6F6F76 
Windows Media (asf),檔案頭:3026B2758E66CF11 
MIDI (mid),檔案頭:4D546864 
*/
    public static String checkType(String xxxx) {
        
        switch (xxxx) {
        case "FFD8FF": return "jpg";
        case "89504E": return "png";
        case "474946": return "jif";

        default: return "0000";
        }
    }

}