blocks|key|699371|text|首先，您应该考虑调用MimeTypeMap#getMimeTypeFromExtension()，如下所示：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|699372|//+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;
}|code-block|syntax|javascript|699373|entityMap^0|A|12|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

First and foremost, you should consider calling <code>MimeTypeMap#getMimeTypeFromExtension()</code>, like this:

<pre><code>// 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;
}
</code></pre>

blocks|key|483556|text|上面的MimeTypeMap解决方案在我的使用中返回null。这是可行的，而且更容易：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|483557|Uri+uri+=+Uri.fromFile(file);
ContentResolver+cR+=+context.getContentResolver();
String+mime+=+cR.getType(uri);|code-block|syntax|javascript|483558|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The MimeTypeMap solution above returned null in my usage. This works, and is easier:

<pre><code>Uri uri = Uri.fromFile(file);
ContentResolver cR = context.getContentResolver();
String mime = cR.getType(uri);
</code></pre>

blocks|key|483614|text|File+file+=+new+File(path,+name);

++++MimeTypeMap+mime+=+MimeTypeMap.getSingleton();
++++int+index+=+file.getName().lastIndexOf('.')%2B1;
++++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();

++++}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|483615|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>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();

 }
</code></pre>

blocks|key|699522|text|非常注意上面umerk44的solution。getMimeTypeFromExtension调用guessMimeTypeTypeFromExtension并且区分大小写。我花了一个下午的时间研究这个问题，然后仔细研究了一下-如果你传递"jpg“，getMimeTypeFromExtension将返回NULL，而如果你传递"JPG”，它将返回"image/jpeg“。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|699523|entityMap|0|LINK|mutability|MUTABLE|url|/users/1019580/umerk44|1|/a/21115175^0|N|O|1D|U|3H|O|48|4|6|7|0|E|8|1|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]|$9|S|A|T|B|C]|$9|U|A|V|B|C]|$9|W|A|X|B|C]]|D|@$9|Y|A|Z|1|10]|$9|11|A|12|1|13]]|E|$]]|$1|F|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]|N|$5|I|J|K|E|$L|O]]]]

Pay super close attention to <a href="/users/1019580/umerk44">umerk44</a>'s <a href="/a/21115175">solution</a> above. <code>getMimeTypeFromExtension</code> invokes <code>guessMimeTypeTypeFromExtension</code> and is CASE SENSITIVE. I spent an afternoon on this then took a closer look - <code>getMimeTypeFromExtension</code> will return <code>NULL</code> if you pass it "JPG" whereas it will return "image/jpeg" if you pass it "jpg".

blocks|key|483605|text|以下是我在Android应用程序中使用的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|483606|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;
++++}|code-block|syntax|javascript|483607|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here is the solution which I used in my Android app:

<pre><code>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;
 }
</code></pre>

blocks|key|483711|text|有时Jeb和Jens的答案不起作用，并返回null。在这种情况下，我使用跟随解决方案。文件头通常包含类型签名。我读了它，并与list+of+signatures中的已知内容进行了比较。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|483712|/**
+*
+*+@param+is+InputStream+on+start+of+file.+Otherwise+signature+can+not+be+defined.
+*+@return+int+id+of+signature+or+-1,+if+unknown+signature+was+found.+See+SIGNATURE_ID_(type)+constants+to
+*++++++identify+signature+by+its+id.
+*+@throws+IOException+in+cases+of+read+errors.
+*/
public+static+int+getSignatureIdFromHeader(InputStream+is)+throws+IOException+{
++++//+read+signature+from+head+of+source+and+compare+with+known+signatures
++++int+signatureId+=+-1;
++++int+sigCount+=+SIGNATURES.length;
++++int[]+byteArray+=+new+int[MAX_SIGNATURE_LENGTH];
++++StringBuilder+builder+=+new+StringBuilder();
++++for+(int+i+=+0;+i+<+MAX_SIGNATURE_LENGTH;+i%2B%2B)+{
++++++++byteArray[i]+=+is.read();
++++++++builder.append(Integer.toHexString(byteArray[i]));
++++}
++++if+(DEBUG)+{
++++++++Log.d(TAG,+"head+bytes="+%2B+builder.toString());
++++}
++++for+(int+i+=+0;+i+<+MAX_SIGNATURE_LENGTH;+i%2B%2B)+{

++++++++//+check+each+bytes+with+known+signatures
++++++++int+bytes+=+byteArray[i];
++++++++int+lastSigId+=+-1;
++++++++int+coincidences+=+0;

++++++++for+(int+j+=+0;+j+<+sigCount;+j%2B%2B)+{
++++++++++++int[]+sig+=+SIGNATURES[j];

++++++++++++if+(DEBUG)+{
++++++++++++++++Log.d(TAG,+"compare"+%2B+i+%2B+":+"+%2B+Integer.toHexString(bytes)+%2B+"+with+"+%2B+sig[i]);
++++++++++++}
++++++++++++if+(bytes+==+sig[i])+{
++++++++++++++++lastSigId+=+j;
++++++++++++++++coincidences%2B%2B;
++++++++++++}
++++++++}

++++++++//+signature+is+unknown
++++++++if+(coincidences+==+0)+{
++++++++++++break;
++++++++}
++++++++//+if+first+bytes+of+signature+is+known+we+check+signature+for+full+coincidence
++++++++if+(coincidences+==+1)+{
++++++++++++int[]+sig+=+SIGNATURES[lastSigId];
++++++++++++int+sigLength+=+sig.length;
++++++++++++boolean+isSigKnown+=+true;
++++++++++++for+(;+i+<+MAX_SIGNATURE_LENGTH+&&+i+<+sigLength;+i%2B%2B)+{
++++++++++++++++bytes+=+byteArray[i];
++++++++++++++++if+(bytes+!=+sig[i])+{
++++++++++++++++++++isSigKnown+=+false;
++++++++++++++++++++break;
++++++++++++++++}
++++++++++++}
++++++++++++if+(isSigKnown)+{
++++++++++++++++signatureId+=+lastSigId;
++++++++++++}
++++++++++++break;
++++++++}
++++}
++++return+signatureId;
}|code-block|syntax|javascript|483713|signatureId是签名数组中的签名索引。例如,|style|CODE|483714|private+static+final+int[]+SIGNATURE_PNG+=+hexStringToIntArray("89504E470D0A1A0A");
private+static+final+int[]+SIGNATURE_JPEG+=+hexStringToIntArray("FFD8FF");
private+static+final+int[]+SIGNATURE_GIF+=+hexStringToIntArray("474946");

public+static+final+int+SIGNATURE_ID_JPEG+=+0;
public+static+final+int+SIGNATURE_ID_PNG+=+1;
public+static+final+int+SIGNATURE_ID_GIF+=+2;
private+static+final+int[][]+SIGNATURES+=+new+int[3][];

static+{
++++SIGNATURES[SIGNATURE_ID_JPEG]+=+SIGNATURE_JPEG;
++++SIGNATURES[SIGNATURE_ID_PNG]+=+SIGNATURE_PNG;
++++SIGNATURES[SIGNATURE_ID_GIF]+=+SIGNATURE_GIF;
}|483715|现在，我有了文件类型，即使文件的URI没有。接下来，我通过文件类型获得mime类型。如果您不知道要获取哪种mime类型，可以在this+table中找到合适的类型。|483716|它适用于很多类型的文件。但对于视频，它不起作用，因为你需要知道视频编解码器才能获得mime类型。为了获得视频的mime类型，我使用了MediaMetadataRetriever。|483717|entityMap|0|LINK|mutability|MUTABLE|url|http://www.filesignatures.net/index.php?page=all%25C2%25A4tpage=1&order=EXT|1|http://www.freeformatter.com/mime-types-list.html|2|http://developer.android.com/reference/android/media/MediaMetadataRetriever.html^0|1Q|I|0|0|0|0|B|0|0|1R|A|1|0|1U|M|2|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@$A|15|B|16|1|17]]|C|$]]|$1|D|3|E|5|F|7|18|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|19|8|@$A|1A|B|1B|K|L]]|9|@]|C|$]]|$1|M|3|N|5|F|7|1C|8|@]|9|@]|C|$G|H]]|$1|O|3|P|5|6|7|1D|8|@]|9|@$A|1E|B|1F|1|1G]]|C|$]]|$1|Q|3|R|5|6|7|1H|8|@]|9|@$A|1I|B|1J|1|1K]]|C|$]]|$1|S|3|-4|5|6|7|1L|8|@]|9|@]|C|$]]]|T|$U|$5|V|W|X|C|$Y|Z]]|10|$5|V|W|X|C|$Y|11]]|12|$5|V|W|X|C|$Y|13]]]]

Sometimes Jeb's and Jens's answers don't work and return null. In this case I use follow solution. Head of file usually contains type signature. I read it and compare with known in <a href="http://www.filesignatures.net/index.php?page=all&amp;currentpage=1&amp;order=EXT" rel="noreferrer">list of signatures</a>.

<pre><code>/**
 *
 * @param is InputStream on start of file. Otherwise signature can not be defined.
 * @return int id of signature or -1, if unknown signature was found. See SIGNATURE_ID_(type) constants to
 * identify signature by its id.
 * @throws IOException in cases of read errors.
 */
public static int getSignatureIdFromHeader(InputStream is) throws IOException {
 // read signature from head of source and compare with known signatures
 int signatureId = -1;
 int sigCount = SIGNATURES.length;
 int[] byteArray = new int[MAX_SIGNATURE_LENGTH];
 StringBuilder builder = new StringBuilder();
 for (int i = 0; i &lt; MAX_SIGNATURE_LENGTH; i++) {
 byteArray[i] = is.read();
 builder.append(Integer.toHexString(byteArray[i]));
 }
 if (DEBUG) {
 Log.d(TAG, "head bytes=" + builder.toString());
 }
 for (int i = 0; i &lt; MAX_SIGNATURE_LENGTH; i++) {

 // check each bytes with known signatures
 int bytes = byteArray[i];
 int lastSigId = -1;
 int coincidences = 0;

 for (int j = 0; j &lt; sigCount; j++) {
 int[] sig = SIGNATURES[j];

 if (DEBUG) {
 Log.d(TAG, "compare" + i + ": " + Integer.toHexString(bytes) + " with " + sig[i]);
 }
 if (bytes == sig[i]) {
 lastSigId = j;
 coincidences++;
 }
 }

 // signature is unknown
 if (coincidences == 0) {
 break;
 }
 // if first bytes of signature is known we check signature for full coincidence
 if (coincidences == 1) {
 int[] sig = SIGNATURES[lastSigId];
 int sigLength = sig.length;
 boolean isSigKnown = true;
 for (; i &lt; MAX_SIGNATURE_LENGTH &amp;&amp; i &lt; sigLength; i++) {
 bytes = byteArray[i];
 if (bytes != sig[i]) {
 isSigKnown = false;
 break;
 }
 }
 if (isSigKnown) {
 signatureId = lastSigId;
 }
 break;
 }
 }
 return signatureId;
}
</code></pre>

<code>signatureId</code> is an index of signature in array of signatures. For example,

<pre><code>private static final int[] SIGNATURE_PNG = hexStringToIntArray("89504E470D0A1A0A");
private static final int[] SIGNATURE_JPEG = hexStringToIntArray("FFD8FF");
private static final int[] SIGNATURE_GIF = hexStringToIntArray("474946");

public static final int SIGNATURE_ID_JPEG = 0;
public static final int SIGNATURE_ID_PNG = 1;
public static final int SIGNATURE_ID_GIF = 2;
private static final int[][] SIGNATURES = new int[3][];

static {
 SIGNATURES[SIGNATURE_ID_JPEG] = SIGNATURE_JPEG;
 SIGNATURES[SIGNATURE_ID_PNG] = SIGNATURE_PNG;
 SIGNATURES[SIGNATURE_ID_GIF] = SIGNATURE_GIF;
}
</code></pre>

Now I have file type even if URI of file haven't. Next I get mime type by file type. If you don't know which mime type to get, you can find proper in <a href="http://www.freeformatter.com/mime-types-list.html" rel="noreferrer">this table</a>.

It works for a lot of file types. But for video it doesn't work, because you need to known video codec to get a mime type. To get video's mime type I use <a href="http://developer.android.com/reference/android/media/MediaMetadataRetriever.html" rel="noreferrer">MediaMetadataRetriever</a>.

blocks|key|699735|text|我尝试使用标准方法来确定mime类型，但无法使用MimeTypeMap.getFileExtensionFromUrl(uri.getPath())保留文件扩展名。此方法返回一个空字符串。因此，我提出了一个很重要的解决方案来保留文件扩展名。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|699736|下面是返回文件扩展名的方法：|699737|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%2B1,+fileName.length());
++++++++}
++++}
++++return+"";
}|code-block|syntax|javascript|699738|保留了文件扩展名后，可以获得如下所示的mime类型：|699739|public+String+getMimeType(File+file)+{
++++String+mimeType+=+"";
++++String+extension+=+getExtension(file.getName());
++++if+(MimeTypeMap.getSingleton().hasExtension(extension))+{
++++++++mimeType+=+MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
++++}
++++return+mimeType;
}|699740|entityMap^0|O|1E|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|X|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|Q|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|R|$]]

I tried to use standard methods to determine the mime type, but I cannot retain the file extension using <code>MimeTypeMap.getFileExtensionFromUrl(uri.getPath())</code>. This method returned me an empty string. So I made a non-trivial solution to retain the file extension.

Here is the method returning the file extension:

<pre><code>private String getExtension(String fileName){
 char[] arrayOfFilename = fileName.toCharArray();
 for(int i = arrayOfFilename.length-1; i &gt; 0; i--){
 if(arrayOfFilename[i] == '.'){
 return fileName.substring(i+1, fileName.length());
 }
 }
 return "";
}
</code></pre>

And having retained the file extension, it is possible to get mime type like below:

<pre><code>public String getMimeType(File file) {
 String mimeType = "";
 String extension = getExtension(file.getName());
 if (MimeTypeMap.getSingleton().hasExtension(extension)) {
 mimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
 }
 return mimeType;
}
</code></pre>

blocks|key|699992|text|编辑|type|unstyled|depth|inlineStyleRanges|entityRanges|data|699993|为此，我创建了一个小型库。但底层代码几乎是相同的。|699994|它可以在GitHub上找到|699995|MimeMagic-Android|offset|length|699996|解决方案2020年9月|699997|使用Kotlin|699998|fun+File.getMimeType(context:+Context):+String?+{
++++if+(this.isDirectory)+{
++++++++return+null
++++}

++++fun+fallbackMimeType(uri:+Uri):+String?+{
++++++++return+if+(uri.scheme+==+ContentResolver.SCHEME_CONTENT)+{
++++++++++++context.contentResolver.getType(uri)
++++++++}+else+{
++++++++++++val+extension+=+MimeTypeMap.getFileExtensionFromUrl(uri.toString())
++++++++++++MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension.toLowerCase(Locale.getDefault()))
++++++++}
++++}

++++fun+catchUrlMimeType():+String?+{
++++++++val+uri+=+Uri.fromFile(this)

++++++++return+if+(Build.VERSION.SDK_INT+>=+Build.VERSION_CODES.O)+{
++++++++++++val+path+=+Paths.get(uri.toString())
++++++++++++try+{
++++++++++++++++Files.probeContentType(path)+?:+fallbackMimeType(uri)
++++++++++++}+catch+(ignored:+IOException)+{
++++++++++++++++fallbackMimeType(uri)
++++++++++++}
++++++++}+else+{
++++++++++++fallbackMimeType(uri)
++++++++}
++++}

++++val+stream+=+this.inputStream()
++++return+try+{
++++++++URLConnection.guessContentTypeFromStream(stream)+?:+catchUrlMimeType()
++++}+catch+(ignored:+IOException)+{
++++++++catchUrlMimeType()
++++}+finally+{
++++++++stream.close()
++++}
}|code-block|syntax|javascript|699999|这似乎是最好的选择，因为它结合了前面的答案。|700000|首先，它尝试使用URLConnection.guessContentTypeFromStream获取类型，但如果失败或返回null，它将尝试在Android及更高版本上使用|700001|java.nio.file.Files
java.nio.file.Paths|700002|否则，如果Android版本低于O，或者该方法失败，它将使用ContentResolver和MimeTypeMap返回类型|700003|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/DATL4G/MimeMagic-Android/tree/v1.0.3^0|0|0|0|0|H|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|18|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|19|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1A|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|1B|8|@]|9|@$H|1C|I|1D|1|1E]]|A|$]]|$1|J|3|K|5|6|7|1F|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|1G|8|@]|9|@]|A|$]]|$1|N|3|O|5|P|7|1H|8|@]|9|@]|A|$Q|R]]|$1|S|3|T|5|6|7|1I|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|1J|8|@]|9|@]|A|$]]|$1|W|3|X|5|P|7|1K|8|@]|9|@]|A|$Q|R]]|$1|Y|3|Z|5|6|7|1L|8|@]|9|@]|A|$]]|$1|10|3|-4|5|6|7|1M|8|@]|9|@]|A|$]]]|11|$12|$5|13|14|15|A|$16|17]]]]

<h1>EDIT</h1>
I created a small library for this.
But the underlying code is nearly the same.
It's available on GitHub
<a href="https://github.com/DATL4G/MimeMagic-Android/tree/v1.0.3" rel="nofollow noreferrer">MimeMagic-Android</a>
<h1>Solution September 2020</h1>
Using Kotlin
<pre><code>fun File.getMimeType(context: Context): String? {
 if (this.isDirectory) {
 return null
 }

 fun fallbackMimeType(uri: Uri): String? {
 return if (uri.scheme == ContentResolver.SCHEME_CONTENT) {
 context.contentResolver.getType(uri)
 } else {
 val extension = MimeTypeMap.getFileExtensionFromUrl(uri.toString())
 MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension.toLowerCase(Locale.getDefault()))
 }
 }

 fun catchUrlMimeType(): String? {
 val uri = Uri.fromFile(this)

 return if (Build.VERSION.SDK_INT &gt;= Build.VERSION_CODES.O) {
 val path = Paths.get(uri.toString())
 try {
 Files.probeContentType(path) ?: fallbackMimeType(uri)
 } catch (ignored: IOException) {
 fallbackMimeType(uri)
 }
 } else {
 fallbackMimeType(uri)
 }
 }

 val stream = this.inputStream()
 return try {
 URLConnection.guessContentTypeFromStream(stream) ?: catchUrlMimeType()
 } catch (ignored: IOException) {
 catchUrlMimeType()
 } finally {
 stream.close()
 }
}
</code></pre>
That seems like the best option as it combines the previous answers.
First it tries to get the type using URLConnection.guessContentTypeFromStream but if this fails or returns null it tries to get the mimetype on Android O and above using
<pre><code>java.nio.file.Files
java.nio.file.Paths
</code></pre>
Otherwise if the Android Version is below O or the method fails it returns the type using ContentResolver and MimeTypeMap

blocks|key|484261|text|它很适合我，而且内容和文件都很灵活|type|unstyled|depth|inlineStyleRanges|entityRanges|data|484262|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+%2520+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;
}|code-block|syntax|javascript|484263|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

its works for me and flexible both for content and file
<pre><code>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;
}
</code></pre>

blocks|key|484323|text|在kotlin中，这要简单得多。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|484324|解决方案1：|484325|fun+getMimeType(file:+File):+String?+=+
++++MimeTypeMap.getSingleton().getMimeTypeFromExtension(file.extension)|code-block|syntax|javascript|484326|解决方案2：(文件扩展名功能)|484327|fun+File.mimeType():+String?+=+
++++MimeTypeMap.getSingleton().getMimeTypeFromExtension(this.extension)|484328|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

In kotlin it's way simpler.
Solution 1:
<pre><code>fun getMimeType(file: File): String? = 
 MimeTypeMap.getSingleton().getMimeTypeFromExtension(file.extension)
</code></pre>
Solution 2: (File extension fuction)
<pre><code>fun File.mimeType(): String? = 
 MimeTypeMap.getSingleton().getMimeTypeFromExtension(this.extension)
</code></pre>

blocks|key|483827|text|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
++++}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|483828|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>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
 }
</code></pre>

blocks|key|483958|text|//+This+will+return+the+mimeType.+
//+for+eg.+xyz.png+it+will+return+image/png.+
//+here+uri+is+the+file+that+we+were+picked+using+intent+from+ext/internal+storage.
private+String+getMimeType(Uri+uri)+{
+++//+This+class+provides+applications+access+to+the+content+model.++
+++ContentResolver+contentResolver+=+getContentResolver();

+++//+getType(Uri+url)-Return+the+MIME+type+of+the+given+content+URL.+
+++return+contentResolver.getType(uri);
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|483959|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>// This will return the mimeType. 
// for eg. xyz.png it will return image/png. 
// here uri is the file that we were picked using intent from ext/internal storage.
private String getMimeType(Uri uri) {
 // This class provides applications access to the content model. 
 ContentResolver contentResolver = getContentResolver();

 // getType(Uri url)-Return the MIME type of the given content URL. 
 return contentResolver.getType(uri);
}
</code></pre>

blocks|key|699871|text|我也遇到过类似的问题。到目前为止，我知道不同的名字可能会有不同的结果，所以最终得出了这个解决方案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|699872|public+String+getMimeType(String+filePath)+{
++++String+type+=+null;
++++String+extension+=+null;
++++int+i+=+filePath.lastIndexOf('.');
++++if+(i+>+0)
++++++++extension+=+filePath.substring(i%2B1);
++++if+(extension+!=+null)
++++++++type+=+MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
++++return+type;
}++|code-block|syntax|javascript|699873|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I faced similar problem. So far I know result may different for different names, so finally came to this solution.

<pre><code>public String getMimeType(String filePath) {
 String type = null;
 String extension = null;
 int i = filePath.lastIndexOf('.');
 if (i &gt; 0)
 extension = filePath.substring(i+1);
 if (extension != null)
 type = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
 return type;
} 
</code></pre>

blocks|key|483584|text|上面的解决方案在.rar文件的情况下返回null，在这种情况下使用URLConnection.guessContentTypeFromName(url)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|483585|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

The above solution returned null in case of .rar file, using URLConnection.guessContentTypeFromName(url) worked in this case.

blocks|key|699624|text|来自本地文件的mime：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|699625|String+url+=+file.getAbsolutePath();
FileNameMap+fileNameMap+=+URLConnection.getFileNameMap();
String+mime+=+fileNameMap.getContentTypeFor("file://"%2Burl);|code-block|syntax|javascript|699626|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

mime from local file:

<pre><code>String url = file.getAbsolutePath();
FileNameMap fileNameMap = URLConnection.getFileNameMap();
String mime = fileNameMap.getContentTypeFor("file://"+url);
</code></pre>

blocks|key|699671|text|您有多个选项来获取文件扩展名:如:+1-String+filename+=+uri.getLastPathSegment();查看此link|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|699672|2-你也可以使用下面的代码|699673|+filePath+.substring(filePath.lastIndexOf(".")%2B1);|code-block|syntax|javascript|699674|但这并不是很好的回答。3-如果您有文件的URI，则使用此代码|699675|String[]+projection+=+{+MediaStore.MediaColumns.DATA,
MediaStore.MediaColumns.MIME_TYPE+};|699676|4-如果你有URL，那么使用下面的代码：|699677|+public+static+String+getMimeType(String+url)+{
String+type+=+null;
String+extension+=+MimeTypeMap.getFileExtensionFromUrl(url);
if+(extension+!=+null)+{+


++type+=+MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
++++}

return+type;
}|699678|享受您的代码：)|699679|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.android.com/reference/android/net/Uri.html#getLastPathSegment()^0|K|17|1U|4|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@$9|17|A|18|1|19]]|E|$]]|$1|F|3|G|5|6|7|1A|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1B|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1C|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|1D|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1E|8|@]|D|@]|E|$]]|$1|S|3|T|5|J|7|1F|8|@]|D|@]|E|$K|L]]|$1|U|3|V|5|6|7|1G|8|@]|D|@]|E|$]]|$1|W|3|-4|5|6|7|1H|8|@]|D|@]|E|$]]]|X|$Y|$5|Z|10|11|E|$12|13]]]]

you have multiple choice to get extension of file:like:
1-<code>String filename = uri.getLastPathSegment();</code> see this <a href="https://developer.android.com/reference/android/net/Uri.html#getLastPathSegment()" rel="nofollow">link</a>

2-you can use this code also

<pre><code> filePath .substring(filePath.lastIndexOf(".")+1);
</code></pre>

but this not good aproch.
3-if you have URI of file then use this Code

<pre><code>String[] projection = { MediaStore.MediaColumns.DATA,
MediaStore.MediaColumns.MIME_TYPE };
</code></pre>

4-if you have URL then use this code:

<pre><code> public static String getMimeType(String url) {
String type = null;
String extension = MimeTypeMap.getFileExtensionFromUrl(url);
if (extension != null) { 


 type = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
 }

return type;
}
</code></pre>

enjoy your code:)

blocks|key|699683|text|//+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);}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|699684|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>// 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);}
</code></pre>

blocks|key|699756|text|public+static+String+getFileType(Uri+file)
{
++++try
++++{
++++++++if+(file.getScheme().equals(ContentResolver.SCHEME_CONTENT))
++++++++++++return+subStringFromLastMark(SystemMaster.getContentResolver().getType(file),+"/");
++++++++else
++++++++++++return+MimeTypeMap.getFileExtensionFromUrl(file.toString()).toLowerCase();
++++}
++++catch(Exception+e)
++++{
++++++++return+null;
++++}
}

public+static+String+getMimeType(Uri+file)
{
++++try
++++{
++++++++return+MimeTypeMap.getSingleton().getMimeTypeFromExtension(getFileType(file));
++++}
++++catch(Exception+e)
++++{
++++++++return+null;
++++}
}

public+static+String+subStringFromLastMark(String+str,String+mark)
{
++++int+l+=+str.lastIndexOf(mark);
++++int+end+=+str.length();
++++if(l+==+-1)
++++++++return+str;

++++return+str.substring(l+%2B+1,+end);
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|699757|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>public static String getFileType(Uri file)
{
 try
 {
 if (file.getScheme().equals(ContentResolver.SCHEME_CONTENT))
 return subStringFromLastMark(SystemMaster.getContentResolver().getType(file), "/");
 else
 return MimeTypeMap.getFileExtensionFromUrl(file.toString()).toLowerCase();
 }
 catch(Exception e)
 {
 return null;
 }
}

public static String getMimeType(Uri file)
{
 try
 {
 return MimeTypeMap.getSingleton().getMimeTypeFromExtension(getFileType(file));
 }
 catch(Exception e)
 {
 return null;
 }
}

public static String subStringFromLastMark(String str,String mark)
{
 int l = str.lastIndexOf(mark);
 int end = str.length();
 if(l == -1)
 return str;

 return str.substring(l + 1, end);
}
</code></pre>

blocks|key|483927|text|这里没有一个答案是完美的。这是一个结合了所有答案中最好的元素的答案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|483928|public+final+class+FileUtil+{

++++//+By+default,+Android+doesn't+provide+support+for+JSON
++++public+static+final+String+MIME_TYPE_JSON+=+"application/json";

++++@Nullable
++++public+static+String+getMimeType(@NonNull+Context+context,+@NonNull+Uri+uri)+{

++++++++String+mimeType+=+null;
++++++++if+(uri.getScheme().equals(ContentResolver.SCHEME_CONTENT))+{
++++++++++++ContentResolver+cr+=+context.getContentResolver();
++++++++++++mimeType+=+cr.getType(uri);
++++++++}+else+{
++++++++++++String+fileExtension+=+getExtension(uri.toString());

++++++++++++if(fileExtension+==+null){
++++++++++++++++return+null;
++++++++++++}

++++++++++++mimeType+=+MimeTypeMap.getSingleton().getMimeTypeFromExtension(
++++++++++++++++++++fileExtension.toLowerCase());

++++++++++++if(mimeType+==+null){
++++++++++++++++//+Handle+the+misc+file+extensions
++++++++++++++++return+handleMiscFileExtensions(fileExtension);
++++++++++++}
++++++++}
++++++++return+mimeType;
++++}

++++@Nullable
++++private+static+String+getExtension(@Nullable+String+fileName){

++++++++if(fileName+==+null+%7C%7C+TextUtils.isEmpty(fileName)){
++++++++++++return+null;
++++++++}

++++++++char[]+arrayOfFilename+=+fileName.toCharArray();
++++++++for(int+i+=+arrayOfFilename.length-1;+i+>+0;+i--){
++++++++++++if(arrayOfFilename[i]+==+'.'){
++++++++++++++++return+fileName.substring(i%2B1,+fileName.length());
++++++++++++}
++++++++}
++++++++return+null;
++++}

++++@Nullable
++++private+static+String+handleMiscFileExtensions(@NonNull+String+extension){

++++++++if(extension.equals("json")){
++++++++++++return+MIME_TYPE_JSON;
++++++++}
++++++++else{
++++++++++++return+null;
++++++++}
++++}
}|code-block|syntax|javascript|483929|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

<h2>None of the answers here are perfect. Here is an answer combining the best elements of all the top answers:</h2>

<pre><code>public final class FileUtil {

 // By default, Android doesn't provide support for JSON
 public static final String MIME_TYPE_JSON = "application/json";

 @Nullable
 public static String getMimeType(@NonNull Context context, @NonNull Uri uri) {

 String mimeType = null;
 if (uri.getScheme().equals(ContentResolver.SCHEME_CONTENT)) {
 ContentResolver cr = context.getContentResolver();
 mimeType = cr.getType(uri);
 } else {
 String fileExtension = getExtension(uri.toString());

 if(fileExtension == null){
 return null;
 }

 mimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(
 fileExtension.toLowerCase());

 if(mimeType == null){
 // Handle the misc file extensions
 return handleMiscFileExtensions(fileExtension);
 }
 }
 return mimeType;
 }

 @Nullable
 private static String getExtension(@Nullable String fileName){

 if(fileName == null || TextUtils.isEmpty(fileName)){
 return null;
 }

 char[] arrayOfFilename = fileName.toCharArray();
 for(int i = arrayOfFilename.length-1; i &gt; 0; i--){
 if(arrayOfFilename[i] == '.'){
 return fileName.substring(i+1, fileName.length());
 }
 }
 return null;
 }

 @Nullable
 private static String handleMiscFileExtensions(@NonNull String extension){

 if(extension.equals("json")){
 return MIME_TYPE_JSON;
 }
 else{
 return null;
 }
 }
}
</code></pre>

blocks|key|483945|text|Intent+myIntent+=+new+Intent(android.content.Intent.ACTION_VIEW);
++++++++++++++++++++++++File+file+=+new+File(filePatch);+
++++++++++++++++++++++++Uri+uris+=+Uri.fromFile(file);
++++++++++++++++++++++++String+mimetype+=+null;
++++++++++++++++++++++++if+
(uris.getScheme().equals(ContentResolver.SCHEME_CONTENT))+{
++++++++++++++++++++++++++++ContentResolver+cr+=+
getApplicationContext().getContentResolver();
++++++++++++++++++++++++++++mimetype+=+cr.getType(uris);
++++++++++++++++++++++++}+else+{
++++++++++++++++++++++++++++String+fileExtension+=+
MimeTypeMap.getFileExtensionFromUrl(uris.toString());
mimetype+=++MimeTypeMap.getSingleton().getMimeTypeFromExtension(fileExtension.toLowerCase());
++++++++++++++++++++++++}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|483946|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>Intent myIntent = new Intent(android.content.Intent.ACTION_VIEW);
 File file = new File(filePatch); 
 Uri uris = Uri.fromFile(file);
 String mimetype = null;
 if 
(uris.getScheme().equals(ContentResolver.SCHEME_CONTENT)) {
 ContentResolver cr = 
getApplicationContext().getContentResolver();
 mimetype = cr.getType(uris);
 } else {
 String fileExtension = 
MimeTypeMap.getFileExtensionFromUrl(uris.toString());
mimetype = MimeTypeMap.getSingleton().getMimeTypeFromExtension(fileExtension.toLowerCase());
 }
</code></pre>

blocks|key|699908|text|我认为最简单的方法是参考这个资源文件：https://android.googlesource.com/platform/libcore/%2B/master/luni/src/main/java/libcore/net/android.mime.types|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|699909|entityMap|0|LINK|mutability|MUTABLE|url|https://android.googlesource.com/platform/libcore/%2B/master/luni/src/main/java/libcore/net/android.mime.types^0|J|30|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

I consider the easiest way is to refer to this Resource file:
<a href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/net/android.mime.types" rel="nofollow noreferrer">https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/net/android.mime.types</a>

Suppose I have a full path of file like:(/sdcard/tlogo.png). I want to know its mime type.

I created a function for it 

<pre><code>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;
}
</code></pre>

but when i call it, it returns null.

<pre><code>File file = new File(filePath);
String fileType=CommonFunctions.getMimeType(file, context);
</code></pre>

How to determine MIME type of file in android?

假设我有一个完整的文件路径，比如：(/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.getConten

问如何在android中确定文件的MIME类型？
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回答 21

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问如何在android中确定文件的MIME类型？EN

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问如何在android中确定文件的MIME类型？
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