java如何判断一个文件的类型

用文件头判断。直接读取文件的前几个字节。

常用文件的文件头如下:
JPEG (jpg),文件头:FFD8FF
PNG (png),文件头:89504E47
GIF (gif),文件头:47494638
TIFF (tif),文件头:49492A00
Windows Bitmap (bmp),文件头:424D
CAD (dwg),文件头:41433130
Adobe Photoshop (psd),文件头:38425053
Rich Text Format (rtf),文件头:7B5C727466
XML (xml),文件头:3C3F786D6C
HTML (html),文件头:68746D6C3E
Email [thorough only] (eml),文件头:44656C69766572792D646174653A
Outlook Express (dbx),文件头:CFAD12FEC5FD746F
Outlook (pst),文件头:2142444E
MS Word/Excel (xls.or.doc),文件头:D0CF11E0
MS Access (mdb),文件头:5374616E64617264204A
WordPerfect (wpd),文件头:FF575043
Postscript (eps.or.ps),文件头:252150532D41646F6265
Adobe Acrobat (pdf),文件头:255044462D312E
Quicken (qdf),文件头:AC9EBD8F
Windows Password (pwl),文件头:E3828596
ZIP Archive (zip),文件头:504B0304
RAR Archive (rar),文件头:52617221
Wave (wav),文件头:57415645
AVI (avi),文件头:41564920
Real Audio (ram),文件头:2E7261FD
Real Media (rm),文件头:2E524D46
MPEG (mpg),文件头:000001BA
MPEG (mpg),文件头:000001B3
Quicktime (mov),文件头:6D6F6F76
Windows Media (asf),文件头:3026B2758E66CF11
MIDI (mid),文件头:4D546864

package org.test;

import java.io.FileInputStream;

public class Test {

    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("D:\\face.jpg");
        byte[] b = new byte[3];
        is.read(b, 0, b.length);
        System.out.println(bytesToHexString(b));

    }

}


你可能感兴趣的:(java如何判断一个文件的类型)