假设我有一个完整的文件路径:(/sdcard/tlogo.png)。我想知道它的mime类型。
我为它创建了一个函数
public static String getMimeType(File file, Context context)
{
Uri uri = Uri.fromFile(file);
ContentResolver cR = context.getContentResolver();
MimeTypeMap mime = MimeTypeMap.getSingleton();
String type = mime.getExtensionFromMimeType(cR.getType(uri));
return type;
}
但当我调用它时，它返回null。
File file = new File(filePath);
String fileType=CommonFunctions.getMimeType(file, context);
当前回答
我尝试使用标准方法来确定mime类型，但我不能使用MimeTypeMap.getFileExtensionFromUrl(uri.getPath())保留文件扩展名。这个方法返回一个空字符串。所以我做了一个重要的解决方案来保留文件扩展名。
下面是返回文件扩展名的方法:
private String getExtension(String fileName){
char[] arrayOfFilename = fileName.toCharArray();
for(int i = arrayOfFilename.length-1; i > 0; i--){
if(arrayOfFilename[i] == '.'){
return fileName.substring(i+1, fileName.length());
}
}
return "";
}
并且保留了文件扩展名，可以获得如下所示的mime类型:
public String getMimeType(File file) {
String mimeType = "";
String extension = getExtension(file.getName());
if (MimeTypeMap.getSingleton().hasExtension(extension)) {
mimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
}
return mimeType;
}
其他回答
首先，你应该考虑调用MimeTypeMap#getMimeTypeFromExtension()，就像这样:
// url = file path or whatever suitable URL you want.
public static String getMimeType(String url) {
String type = null;
String extension = MimeTypeMap.getFileExtensionFromUrl(url);
if (extension != null) {
type = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
}
return type;
}
它适用于我和灵活的内容和文件
public static String getMimeType(Context context, Uri uri) {
String extension;
//Check uri format to avoid null
if (uri.getScheme().equals(ContentResolver.SCHEME_CONTENT)) {
//If scheme is a content
final MimeTypeMap mime = MimeTypeMap.getSingleton();
extension = mime.getExtensionFromMimeType(context.getContentResolver().getType(uri));
} else {
//If scheme is a File
//This will replace white spaces with %20 and also other special characters. This will avoid returning null values on file name with spaces and special characters.
extension = MimeTypeMap.getFileExtensionFromUrl(Uri.fromFile(new File(uri.getPath())).toString());
}
return extension;
}
我认为最简单的方法是引用这个资源文件: https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/net/android.mime.types
File file = new File(path, name);
MimeTypeMap mime = MimeTypeMap.getSingleton();
int index = file.getName().lastIndexOf('.')+1;
String ext = file.getName().substring(index).toLowerCase();
String type = mime.getMimeTypeFromExtension(ext);
intent.setDataAndType(Uri.fromFile(file), type);
try
{
context.startActivity(intent);
}
catch(ActivityNotFoundException ex)
{
ex.printStackTrace();
}
// new processing the mime type out of Uri which may return null in some cases
String mimeType = getContentResolver().getType(uri);
// old processing the mime type out of path using the extension part if new way returned null
if (mimeType == null){mimeType URLConnection.guessContentTypeFromName(path);}
