android - AssetManager.openFd(filename) 返回 null

问题描述

那是我的代码。我在 getAssets()?.openFd(sf.path) 上得到 FileNotFoundException？但是这个文件存在！

fun addSong(sf: File){
    val fd0 = context?.getAssets()?.openFd(sf.path)?.getFileDescriptor()
    val mmr = MediaMetadataRetriever()
    mmr.setDataSource(fd0)

    val s = Song()
    s.file = sf
    s.album = mmr.extractMetadata(MediaMetadataRetriever.METADATA_KEY_ALBUM)
    allsongs = allsongs.plusElement(s)
}

class Song{
    var file: File? = null
    var album: String
}

这是堆栈跟踪

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: filodev.com.musicplayer, PID: 21382
              java.lang.RuntimeException: Unable to start activity ComponentInfo{filodev.com.musicplayer/filodev.com.musicplayer.MainActivity}: java.io.FileNotFoundException: filename
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2830)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2905)
                  at android.app.ActivityThread.-wrap11(Unknown Source:0)
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1606)
                  at android.os.Handler.dispatchMessage(Handler.java:105)
                  at android.os.Looper.loop(Looper.java:169)
                  at android.app.ActivityThread.main(ActivityThread.java:6595)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
               Caused by: java.io.FileNotFoundException: filename
                  at android.content.res.AssetManager.openAssetFd(Native Method)
                  at android.content.res.AssetManager.openFd(AssetManager.java:390)
                  at filodev.com.musicplayer.FileFinder.addSong(FileFinder.kt:54)
                  at filodev.com.musicplayer.FileFinder.startFind(FileFinder.kt:48)
                  at filodev.com.musicplayer.FileFinder.startFind(FileFinder.kt:43)
                  at filodev.com.musicplayer.FileFinder.startFind(FileFinder.kt:43)
                  at filodev.com.musicplayer.FileFinder.startFind(FileFinder.kt:43)
                  at filodev.com.musicplayer.FileFinder.find(FileFinder.kt:34)
                  at filodev.com.musicplayer.MainActivity.checkPermission(MainActivity.kt:35)
                  at filodev.com.musicplayer.MainActivity.onCreate(MainActivity.kt:23)
                  at android.app.Activity.performCreate(Activity.java:7016)
                  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2783)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2905) 
                  at android.app.ActivityThread.-wrap11(Unknown Source:0) 
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1606) 
                  at android.os.Handler.dispatchMessage(Handler.java:105) 
                  at android.os.Looper.loop(Looper.java:169) 
                  at android.app.ActivityThread.main(ActivityThread.java:6595) 
                  at java.lang.reflect.Method.invoke(Native Method) 
                  at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

我已经在清单中添加了外部存储读写权限。如果文件存在，为什么我会收到此异常？

标签： androidkotlin

android - AssetManager.openFd(filename) 返回 null

问题描述

解决方案

推荐阅读