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
get file object....
File file = new File(filePath);
then....pass as a parameter to...
getMimeType(file);
...here is
public String getMimeType(File file) {
String mimetype = MimeTypeMap.getSingleton().getMimeTypeFromExtension(MimeTypeMap.getFileExtensionFromUrl(Uri.fromFile(file).toString()).toLowerCase());
if (mimetype == null) {
return "*/*";
}
return mimetype;///return the mimeType
}
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;
}
Mime从本地文件:
String url = file.getAbsolutePath();
FileNameMap fileNameMap = URLConnection.getFileNameMap();
String mime = fileNameMap.getContentTypeFor("file://"+url);
以下是我在我的Android应用程序中使用的解决方案:
public static String getMimeType(String url)
{
String extension = url.substring(url.lastIndexOf("."));
String mimeTypeMap = MimeTypeMap.getFileExtensionFromUrl(extension);
String mimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(mimeTypeMap);
return mimeType;
}
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;
}
在kotlin中，这要简单得多。
解决方案1:
fun getMimeType(file: File): String? =
MimeTypeMap.getSingleton().getMimeTypeFromExtension(file.extension)
方案二:(文件扩展名函数)
fun File.mimeType(): String? =
MimeTypeMap.getSingleton().getMimeTypeFromExtension(this.extension)
