about how Android intercepts thumbnails and what problems they encounter

A recent project needs to write to the recording video and then intercept the thumbnail display feature. In the previous wording is called the system's own camera function, but the effect is poor.

Later I intend to write a method of recording the video myself, successfully, and save it in the local path.

However, when extracting thumbnails, a series of problems are encountered.

A great God told me to read it from the database. But their level is somewhat low, has not studied the database read and write files.

Thus, one way to find out online is to mediametadataretriever this class.

Don't say much nonsense, put on the code.

public class Mainactivity extends Activity {private Button btn;private ImageView iv;static String TAG = "mainactivity"; String path; @Overrideprotected void OnCreate (Bundle savedinstancestate) {super.oncreate (savedinstancestate); Setcontentview (r.layout.activity_main); btn = (Button) Findviewbyid (R.id.button); iv = (ImageView) Findviewbyid ( R.ID.IV); Btn.setonclicklistener (new Onclicklistener () {@Overridepublic void OnClick (View v) {//TODO auto-generated method stub bitmap Bitmap;//file file = new file (Getapplicationcontext (). Getfilesdir (),//"/see.mp4"); try {path = Environment.getexternalstoragedirectory (). Getcanonicalfile () + "/see.mp4"; LOG.E (TAG, path);} catch (IOException E1) {//TODO auto-generated catch block E1.printstacktrace ();} Mediametadataretriever MMR = new Mediametadataretriever ();//System.out.println (Uri.fromfile (file). toString ()); Mmr.setdatasource (path); bitmap = Mmr.getframeattime (1 * +); Iv.setimagebitmap (bitmap); System.out.println (Mmr.extractmetadata (mediametadataretriever.metadata_key_date) + "");System.out.println (Mmr.extractmetadata (mediametadataretriever.metadata_key_mimetype) + ""); Mmr.release ();}});} 

Layout file is simple

<relativelayout      xmlns:android= "http://schemas.android.com/apk/res/android"      xmlns:tools= "http// Schemas.android.com/tools "      android:layout_width=" match_parent "      android:layout_height=" Match_parent "      >        <button          android:id= "@+id/button"          android:layout_width= "Wrap_content"          android: layout_height= "Wrap_content"          android:text= "get frame picture of video"           android:layout_centerinparent= "true"      />      <imageview        android:id= "@+id/iv"        android:layout_width= "fill_parent"        android:layout_ height= "Match_parent"        android:layout_below= "@id/button"        ></ImageView>  </ Relativelayout>  

One of the problems encountered earlier is that you cannot read files under this path. Instead, read it with a URI, and the problem is found.

I finally found out that there was something missing on the authority.

<uses-permission android:name= "Android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<uses-permission android:name= "Android.permission.WRITE_EXTERNAL_STORAGE"/>

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about how Android intercepts thumbnails and what problems they encounter