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
// 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);}
其他回答
检测任何文件的mime类型
public String getMimeType(Uri uri) {
String mimeType = null;
if (ContentResolver.SCHEME_CONTENT.equals(uri.getScheme())) {
ContentResolver cr = getAppContext().getContentResolver();
mimeType = cr.getType(uri);
} else {
String fileExtension = MimeTypeMap.getFileExtensionFromUrl(uri
.toString());
mimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(
fileExtension.toLowerCase());
}
return mimeType;
}
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;
}
上面的MimeTypeMap解决方案在我的使用中返回null。这很有效，而且更简单:
Uri uri = Uri.fromFile(file);
ContentResolver cR = context.getContentResolver();
String mime = cR.getType(uri);
I don't realize why MimeTypeMap.getFileExtensionFromUrl() has problems with spaces and some other characters, that returns "", but I just wrote this method to change the file name to an admit-able one. It's just playing with Strings. However, It kind of works. Through the method, the spaces existing in the file name is turned into a desirable character (which, here, is "x") via replaceAll(" ", "x") and other unsuitable characters are turned into a suitable one via URLEncoder. so the usage (according to the codes presented in the question and the selected answer) should be something like getMimeType(reviseUrl(url)).
private String reviseUrl(String url) {
String revisedUrl = "";
int fileNameBeginning = url.lastIndexOf("/");
int fileNameEnding = url.lastIndexOf(".");
String cutFileNameFromUrl = url.substring(fileNameBeginning + 1, fileNameEnding).replaceAll(" ", "x");
revisedUrl = url.
substring(0, fileNameBeginning + 1) +
java.net.URLEncoder.encode(cutFileNameFromUrl) +
url.substring(fileNameEnding, url.length());
return revisedUrl;
}
对于Xamarin Android(来自@HoaLe的回答)
public String getMimeType(Uri uri) {
String mimeType = null;
if (uri.Scheme.Equals(ContentResolver.SchemeContent))
{
ContentResolver cr = Application.Context.ContentResolver;
mimeType = cr.GetType(uri);
}
else
{
String fileExtension = MimeTypeMap.GetFileExtensionFromUrl(uri.ToString());
mimeType = MimeTypeMap.Singleton.GetMimeTypeFromExtension(
fileExtension.ToLower());
}
return mimeType;
}
