Android中Java根据文件头获取文件类型

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); } }

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