javascript字节数组转换为16进制/**
* byte数组转换成16进制字符串
* @param src
* @return
*/
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 = HexString(v);
if (hv.length() < 2) {
stringBuilder.append(0);
}
stringBuilder.append(hv);
}
String();
}
/**
* 根据⽂件流读取图⽚⽂件真实类型
* @param is
* @return
*/
public static String getTypeByStream(FileInputStream is){
byte[] b = new byte[4];
try {
} catch (IOException e) {
e.printStackTrace();
}
String type = bytesToHexString(b).toUpperCase();
ains("FFD8FF")){
return "jpg";
}else ains("89504E47")){
return "png";
}else ains("47494638")){
return "gif";
}else ains("49492A00")){
return "tif";
}else ains("424D")){
return "bmp";
}
return type;
}
public static void main(String[] args) throws Exception {
// String src = "D:/workspace//8129.jpg";
// String src = "D:/workspace//temp/1.gif";
String src = "D:/workspace//temp/2.bmp";
FileInputStream is = new FileInputStream(src);
// byte[] b = new byte[4];
// is.read(b, 0, b.length);
// System.out.println(bytesToHexString(b));
String type = getTypeByStream(is);
System.out.println(type);
/*
* 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
*/
}
==================================
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 (doc)，⽂件头：D0CF11E0
MS Access (mdb)，⽂件头：5374616E64617264204A
WordPerfect (wpd)，⽂件头：FF575043
Postscript. (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
javascript数组对象
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