創建一個非索引的文件夾導致IOException

Question

我想創建一個主文件夾，應用程序應該使用它來保存其所有文件。如果已經存在的文件夾創建的目錄應該被忽略

這裏我嘗試

public static void createFolder() { 
     String baseDir = Environment.getExternalStorageDirectory().getAbsolutePath(); 
     String baseAppDir = "MyAppFolder"; 
     String fileHider = ".nomedia"; 
     File mainDirectory = new File(baseDir + File.separator + baseAppDir); 

     if (!(mainDirectory.exists())) { 
      mainDirectory.mkdirs(); 

      File outputFile = new File(mainDirectory, fileHider); 

      try { 
       FileOutputStream fos = new FileOutputStream(outputFile); 
      } catch (FileNotFoundException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
     } 

    } 

遺憾的是不工作，得到這個錯誤，並創建沒有文件夾

12-07 17:16:01.127: W/System.err(1855): java.io.FileNotFoundException: /storage/sdcard/MyAppFolder/.nomedia: open failed: ENOENT (No such file or directory) 
12-07 17:16:01.167: W/System.err(1855):  at libcore.io.IoBridge.open(IoBridge.java:409) 
12-07 17:16:01.167: W/System.err(1855):  at java.io.FileOutputStream.<init>(FileOutputStream.java:88) 
12-07 17:16:01.177: W/System.err(1855):  at java.io.FileOutputStream.<init>(FileOutputStream.java:73) 
    .... 

我的清單

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="it.myapp.test" 
    android:versionCode="1" 
    android:versionName="1.0" > 

    <uses-sdk 
     android:minSdkVersion="14" 
     android:targetSdkVersion="18" /> 

    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> 
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> 
    <uses-permission android:name="android.permission.ACCESS_GPS" /> 
    <uses-permission android:name="android.permission.ACCESS_LOCATION" /> 
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> 
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" /> 
    <uses-permission android:name="android.permission.AUTHENTICATE_ACCOUNTS" /> 
    <uses-permission android:name="android.permission.CAMERA" /> 
    <uses-permission android:name="android.permission.FLASHLIGHT" /> 
    <uses-permission android:name="android.permission.GET_ACCOUNTS" /> 
    <uses-permission android:name="android.permission.WAKE_LOCK" /> 
    <uses-permission android:name="android.permission.INTERNET" /> 
    <uses-permission android:name="android.permission.SEND_SMS" /> 
    <uses-permission android:name="android.permission.CALL_PHONE" /> 
    <uses-permission android:name="android.permission.READ_CONTACTS" /> 
    <uses-permission android:name="android.permission.READ_CALENDAR" /> 
    <uses-permission android:name="android.permission.VIBRATE" /> 
    <uses-permission android:name="android.permission.USE_CREDENTIALS" /> 
    <uses-permission android:name="android.permission.WRITE_CALENDAR" /> 
    <uses-permission android:name="android.permission.WRITE_SOCIAL_STREAM" /> 
    <uses-permission android:name="android.permission.WRITE_SYNC_SETTINGS" /> 
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> 


    <application 
     android:allowBackup="true" 
     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme" > 
     <activity 
      android:name="it.myapp.test.MainActivity" 
      android:label="@string/app_name" > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 

       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
    </application> 

</manifest> 

編輯

在主要活動，如果我嘗試在createFolder使用嘗試捕捉具有的printStackTrace（）我得到這個錯誤日誌

12-07 18:28:26.090: W/dalvikvm(3335): Exception Ljava/lang/NullPointerException; thrown while initializing Lit/myapp/test/FileArchiveManager; 
12-07 18:28:26.210: W/System.err(3335): java.lang.ExceptionInInitializerError 
12-07 18:28:26.220: W/System.err(3335):  at it.myapp.test.MainActivity.onCreate(MainActivity.java:19) 
12-07 18:28:26.220: W/System.err(3335):  at android.app.Activity.performCreate(Activity.java:5243) 
12-07 18:28:26.230: W/System.err(3335):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) 
12-07 18:28:26.240: W/System.err(3335):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2140) 
12-07 18:28:26.240: W/System.err(3335):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226) 
12-07 18:28:26.240: W/System.err(3335):  at android.app.ActivityThread.access$700(ActivityThread.java:135) 
12-07 18:28:26.250: W/System.err(3335):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397) 
12-07 18:28:26.250: W/System.err(3335):  at android.os.Handler.dispatchMessage(Handler.java:102) 
12-07 18:28:26.260: W/System.err(3335):  at android.os.Looper.loop(Looper.java:137) 
12-07 18:28:26.260: W/System.err(3335):  at android.app.ActivityThread.main(ActivityThread.java:4998) 
12-07 18:28:26.280: W/System.err(3335):  at java.lang.reflect.Method.invokeNative(Native Method) 
12-07 18:28:26.280: W/System.err(3335):  at java.lang.reflect.Method.invoke(Method.java:515) 
12-07 18:28:26.280: W/System.err(3335):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777) 
12-07 18:28:26.290: W/System.err(3335):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593) 
12-07 18:28:26.290: W/System.err(3335):  at dalvik.system.NativeStart.main(Native Method) 
12-07 18:28:26.300: W/System.err(3335): Caused by: java.lang.NullPointerException: name == null 
12-07 18:28:26.310: W/System.err(3335):  at java.io.File.<init>(File.java:150) 
12-07 18:28:26.310: W/System.err(3335):  at java.io.File.<init>(File.java:124) 
12-07 18:28:26.320: W/System.err(3335):  at android.os.Environment.buildPath(Environment.java:812) 
12-07 18:28:26.320: W/System.err(3335):  at android.os.Environment.buildPaths(Environment.java:796) 
12-07 18:28:26.330: W/System.err(3335):  at android.os.Environment$UserEnvironment.buildExternalStoragePublicDirs(Environment.java:199) 
12-07 18:28:26.330: W/System.err(3335):  at android.os.Environment.getExternalStoragePublicDirectory(Environment.java:538) 
12-07 18:28:26.340: W/System.err(3335):  at it.myapp.test.utility.FileArchiveManager.<clinit>(FileArchiveManager.java:17) 
12-07 18:28:26.340: W/System.err(3335):  ... 15 more 

Answer 1

添加WRITE_EXTERNAL_STORAGE權限。如果您的應用程序可以寫入getExternalFilesDir()，但不能寫入外部存儲上的其他地方，這應該意味着：

1. 您在Android 4.4+測試和

2. 您沒有權限WRITE_EXTERNAL_STORAGE

Answer 2

你的代碼將與只有紮根的設備。
要解決此問題，您必須將文件放在標準目錄（Environment.getExternalStoragePublicDirectory()）中。