前面贴过Android系统内部的MediaFile类来获取文件类型的办法，这个类主要是根据文件的扩展名来判断，其准确性不是很好。具体可查看Android系统使用MediaFile类判断音频文件类型。其实，获取文件类型最好的办法便是根据文件头信息来判断。下面贴出相关代码：
public class FileType {
public static final HashMap<String, String> mFileTypes = new HashMap<String, String>();
static {
//images
mFileTypes.put("FFD8FF", "jpg");
mFileTypes.put("89504E47", "png");
mFileTypes.put("47494638", "gif");
mFileTypes.put("49492A00", "tif");
mFileTypes.put("424D", "bmp");
//
mFileTypes.put("41433130", "dwg"); //CAD
mFileTypes.put("38425053", "psd");
mFileTypes.put("7B5C727466", "rtf"); //日记本
mFileTypes.put("3C3F786D6C", "xml");
mFileTypes.put("68746D6C3E", "html");
mFileTypes.put("44656C69766572792D646174653A", "eml"); //邮件
mFileTypes.put("D0CF11E0", "doc");
mFileTypes.put("5374616E64617264204A", "mdb");
mFileTypes.put("252150532D41646F6265", "ps");
mFileTypes.put("255044462D312E", "pdf");
mFileTypes.put("504B0304", "zip");
mFileTypes.put("52617221", "rar");
mFileTypes.put("57415645", "wav");
mFileTypes.put("41564920", "avi");
mFileTypes.put("2E524D46", "rm");
mFileTypes.put("000001BA", "mpg");
mFileTypes.put("000001B3", "mpg");
mFileTypes.put("6D6F6F76", "mov");
mFileTypes.put("3026B2758E66CF11", "asf");
mFileTypes.put("4D546864", "mid");
mFileTypes.put("1F8B08", "gz");
mFileTypes.put("", "");
mFileTypes.put("", "");
}
public static String getFileType(String filePath) {
return mFileTypes.get(getFileHeader(filePath));
}
//获取文件头信息
public static String getFileHeader(String filePath) {
FileInputStream is = null;
String value = null;
try {
is = new FileInputStream(filePath);
byte[] b = new byte[3];
is.read(b, 0, b.length);
value = bytesToHexString(b);
} catch (Exception e) {
} finally {
if(null != is) {
try {
is.close();
} catch (IOException e) {}
}
}
return value;
}
private static String bytesToHexString(byte[] src){
StringBuilder builder = new StringBuilder();
if (src == null || src.length <= 0) {
return null;
}
String hv;
for (int i = 0; i < src.length; i++) {
hv = Integer.toHexString(src[i] & 0xFF).toUpperCase();
if (hv.length() < 2) {
builder.append(0);
}
builder.append(hv);
}
return builder.toString();
}
public static void main(String[] args) throws Exception {
final String fileType = getFileType("D:/apache-tomcat-6.0.35.tar.gz");
System.out.println(fileType);
}
}