java.lang.IllegalArgumentException: Invalid path解决方案

功能：读取外置存储的信息。

现象：在反弹插拔TF卡之后，会弹出强制关闭

概率：反复插拔TF卡会出现，在一定时间内多次插拔，可以达到必现

Logcat：

E/AndroidRuntime( 2920): FATAL EXCEPTION: main
E/AndroidRuntime( 2920): Process: com.borqs.factorytest, PID: 2920
E/AndroidRuntime( 2920): java.lang.RuntimeException: Error receiving broadcast Intent { act=android.intent.action.MEDIA_MOUNTED dat=file:///mnt/external_sd flg=0x4000010 (has extras) } in com.borqs.factorytest.activity.ComprehensiveTest$7@1de3ce77
E/AndroidRuntime( 2920): at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:876)
E/AndroidRuntime( 2920): at android.os.Handler.handleCallback(Handler.java:739)
E/AndroidRuntime( 2920): at android.os.Handler.dispatchMessage(Handler.java:95)
E/AndroidRuntime( 2920): at android.os.Looper.loop(Looper.java:135)
E/AndroidRuntime( 2920): at android.app.ActivityThread.main(ActivityThread.java:5280)
E/AndroidRuntime( 2920): at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime( 2920): at java.lang.reflect.Method.invoke(Method.java:372)
E/AndroidRuntime( 2920): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:963)
E/AndroidRuntime( 2920): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:758)
E/AndroidRuntime( 2920): Caused by: java.lang.IllegalArgumentException: Invalid path: /mnt/external_sd
E/AndroidRuntime( 2920): at android.os.StatFs.doStat(StatFs.java:46)
E/AndroidRuntime( 2920): at android.os.StatFs.<init>(StatFs.java:39)
E/AndroidRuntime( 2920): at com.borqs.factorytest.activity.ComprehensiveTest.measureApproximateStorage(ComprehensiveTest.java:1001)
E/AndroidRuntime( 2920): at com.borqs.factorytest.activity.ComprehensiveTest.measureApproximateStorageAndRamAndRomAndCPU(ComprehensiveTest.java:945)
E/AndroidRuntime( 2920): at com.borqs.factorytest.activity.ComprehensiveTest.access$700(ComprehensiveTest.java:54)
E/AndroidRuntime( 2920): at com.borqs.factorytest.activity.ComprehensiveTest$7.onReceive(ComprehensiveTest.java:771)
E/AndroidRuntime( 2920): at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:866)
E/AndroidRuntime( 2920): ... 8 more
E/AndroidRuntime( 2920): Caused by: android.system.ErrnoException: statvfs failed: EIO (I/O error)
E/AndroidRuntime( 2920): at libcore.io.Posix.statvfs(Native Method)
E/AndroidRuntime( 2920): at libcore.io.BlockGuardOs.statvfs(BlockGuardOs.java:298)
E/AndroidRuntime( 2920): at android.system.Os.statvfs(Os.java:459)
E/AndroidRuntime( 2920): at android.os.StatFs.doStat(StatFs.java:44)
E/AndroidRuntime( 2920): ... 14 more

源码：

// sd card ext
if(Environment.getExternalStorageDirectory().getPath().equals("/storage/emulated/0")) {
    if((new File("/mnt/sdcard_ext")).exists()) {
        stat = new StatFs("/mnt/sdcard_ext");
    } else if(!mSdPath.equals("")) {
        if((new File(mSdPath)).exists()) {
        stat = new StatFs(mSdPath);//-------------出错行
    }
} else {
    callShellCommand_Sdcard("mount");
    mSdPath = "/storage/" + mSdPath.substring(mSdPath.lastIndexOf("/") + 1);
    if((new File(mSdPath)).exists()) {
        stat = new StatFs(mSdPath);
    }
}

解决方案：

在AndroidManifest.xml添加permission
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

解决原理：

1. 看log

    抛出了java.lang.IllegalArgumentException: Invalid path: /mnt/external_sd
    传入的参数不合法，具体是非法路径。问题出在这个地址上.
    E/AndroidRuntime( 2920): at android.os.StatFs.doStat(StatFs.java:46)
    E/AndroidRuntime( 2920): at android.os.StatFs.<init>(StatFs.java:39)
    执行初始化的的时候挂的

2.看源码错误位置

    new StatFs(mSdPath);

3.得出可能结论

    或许是因为文件读写出问题

4. 看docs

READ_EXTERNAL_STORAGE

added in  API level 16

String READ_EXTERNAL_STORAGE

Allows an application to read from external storage.

Any app that declares the WRITE_EXTERNAL_STORAGE permission is implicitly granted this permission.

This permission is enforced starting in API level 19. Before API level 19, this permission is not enforced and all apps still have access to read from external storage. You can test your app with the permission enforced by enabling Protect USB storage under Developer options in the Settings app on a device running Android 4.1 or higher.

Also starting in API level 19, this permission is not required to read/write files in your application-specific directories returned by getExternalFilesDir(String)and getExternalCacheDir().

Note: If both your minSdkVersion and targetSdkVersion values are set to 3 or lower, the system implicitly grants your app this permission. If you don't need this permission, be sure your targetSdkVersion is 4 or higher.

Protection level: dangerous

Constant Value: "android.permission.READ_EXTERNAL_STORAGE"

对文件进行读写的话，都需要这个权限，那么获取这个信息，说不定也需要这个权限。