Android MediaScanner 总纲 _Android

相逢意气为君饮，系马高楼垂柳边。这篇文章主要讲述Android MediaScanner 总纲相关的知识，希望能为你提供帮助。
1. MediaScanner HEAD

文章图片

2. 应用层 MediaProviderpackages\providers\MediaProvider
(1) MediaProvider
packages\providers\MediaProvider\MediaProvider.java
MediaProvider继承于ContentProvider,主要用于创建媒体库的数据库表.
具体内容请查阅怎样创建Provider.
MediaProvider中包涵一个BroadcastReceiver,用于监听SDCard挂载/卸载
(2) MediaReceiver
监听扫描事件, 调用MSS
Action :
Intent.ACTION_BOOT_COMPLETED, Intent.ACTION_MEDIA_MOUNTED
scan volume MediaScannerService
else
scanFile filepath MediaScannerService
(3) MediaScannerService MSS
onStartCommand==> ServiceHandler==> scanFile
当我们调用startService的时候。假设相应的Service还未创建就会调用onCreate方法===方法。
每次startService的时候就调用onStartCommand，所以ServiceHandler就在此发送消息了。

call: MediaScanner :: scanSingleFile, scanDirectories
3. JAVA 层Call Stack : Google注解

/* * In summary: * Java MediaScannerService calls * Java MediaScanner scanDirectories, which calls * Java MediaScanner processDirectory (native method), which calls * native MediaScanner processDirectory, which calls * native MyMediaScannerClient scanFile, which calls * Java MyMediaScannerClient scanFile, which calls * Java MediaScannerClient doScanFile, which calls * Java MediaScanner processFile (native method), which calls * native MediaScanner processFile, which calls * native parseMP3, parseMP4, parseMidi, parseOgg or parseWMA, which calls * native MyMediaScanner handleStringTag, which calls * Java MyMediaScanner handleStringTag. * Once MediaScanner processFile returns, an entry is inserted in to the database. */

文章图片

(1) MediaScanner
frameworks/base/media/java/android/media/MediaScanner.java
Call JNI

static { System.loadLibrary("media_jni"); native_init(); }

scanDirectories ? jni processDirectory
scanSingleFile ==> MyMediaScannerClient.doScanFile
deal with image, audio, video ? jni processFile
4. JNI层(1) android_media_MediaScanner.cpp
frameworks\base\media\jni\android_media_MediaScanner.cpp
MediaScanner *mp = getNativeScanner_l(env, thiz);
mp-> processDirectory(pathStr, myClient);
mp-> processFile(pathStr, mimeTypeStr, myClient);
android_media_MediaScanner中比較重要的是MyMediaScannerClient类, 该类会被继续传究竟层,用于调用java层(MediaScanner.java)的 scanFile, handleStringTag, setMimeType
5. Server Proxyerlibmedia – libmedia.so
frameworks\av\media\libmedia\MediaScanner.cpp
处理具体的文件
假设是目录须要返回JAVA层中,採用scanFile处理
6. Server【Android MediaScanner 总纲】frameworks\av\media\libstagefright\StagefrightMediaScanner.cpp
libstagefright.so
依据文件后缀推断可处理的文件
然后通过MediaMetadataRetriever获取视频的具体信息,
最后同过handleString一步一步向上传, 在MediaScannerService中把信息写入数据库.