java.io.FileNotFoundException，打开失败：ENOENT

Question

出于某种原因，我两次阅读时都得到了 fileNotFoundException 。值得注意的是 Toast 打印“文件存在！”。我用最下面的 BufferedReader 来测试文件内容是否正确。

 @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fragment_calendar, container, false);

    recipes = new ArrayMap<>();
    filename = "calendar_recipes.txt";

    bText= (EditText) v.findViewById(R.id.bEditText);
    lText= (EditText) v.findViewById(R.id.lEditText);
    dText= (EditText) v.findViewById(R.id.dEditText);

    cal = (CalendarView) v.findViewById(R.id.calendarView);
    date = cal.getDate();

    File file = getActivity().getFileStreamPath(filename);

    if(file.exists())
    {
        Toast.makeText(getActivity(), "File exists!", Toast.LENGTH_SHORT).show();
        try
        {
            FileInputStream fileInputStream = new FileInputStream(getActivity().getFilesDir()+filename);
            ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
            Map recipes = (Map)objectInputStream.readObject();
        }
        catch(ClassNotFoundException | IOException | ClassCastException e) {
            e.printStackTrace();
        }
    }
    else
    {
        Toast.makeText(getActivity(), "File does not exist!!", Toast.LENGTH_SHORT).show();
        file = new File(getActivity().getFilesDir(), filename);
    }

    try {
        BufferedReader in = new BufferedReader(new FileReader(filename));
        String line;
        while ((line = in.readLine()) != null) {
            System.out.println(line);
        }
        in.close();
    }

    catch (IOException e) {
        e.printStackTrace();
    }

日志…

 03-24 23:54:57.626 14059-14067/com.stringcheese.recipez.recip_ez W/art: Suspending all threads took: 7.202ms
03-24 23:54:58.409 14059-14059/com.stringcheese.recipez.recip_ez W/System.err: java.io.FileNotFoundException: /data/data/com.stringcheese.recipez.recip_ez/filescalendar_recipes.txt: open failed: ENOENT (No such file or directory)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:456)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at java.io.FileInputStream.<init>(FileInputStream.java:76)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at java.io.FileInputStream.<init>(FileInputStream.java:103)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at com.stringcheese.recipez.recip_ez.CalendarFragment.onCreateView(CalendarFragment.java:80)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1974)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1252)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1617)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.support.v4.app.FragmentController.execPendingActions(FragmentController.java:339)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:602)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1259)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.app.Activity.performStart(Activity.java:6026)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2302)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2413)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.app.ActivityThread.access$800(ActivityThread.java:155)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1317)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:102)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.os.Looper.loop(Looper.java:135)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5343)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
03-24 23:54:58.410 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at java.lang.reflect.Method.invoke(Method.java:372)
03-24 23:54:58.411 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:907)
03-24 23:54:58.411 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:702)
03-24 23:54:58.411 14059-14059/com.stringcheese.recipez.recip_ez W/System.err: Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
03-24 23:54:58.411 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at libcore.io.Posix.open(Native Method)
03-24 23:54:58.411 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
03-24 23:54:58.411 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:442)
03-24 23:54:58.411 14059-14059/com.stringcheese.recipez.recip_ez W/System.err:  ... 23 more

原文由 D. Rao 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

getFilesDir 返回一个文件对象。如果你在它上面调用 onString（你隐式地这样做），它会返回它的路径。如果文件是目录，则路径 不 以斜杠结尾，因此 getActivity().getFilesDir()+filename 将导致类似 "/data/data/com.yourapp/filescalendar_recipes.txt" 的结果。

您可以使用 getActivity().getFilesDir()+File.separator+filename ，或者只调用 new FileInputStream(file) 。

原文由 F43nd1r 发布，翻译遵循 CC BY-SA 3.0 许可协议

Answer 2

我遇到了同样的错误。 这个 答案对我有用。

您只需在清单中添加一行，如下所示：

 <application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:requestLegacyExternalStorage="true" //Add this Line
android:label="@string/app_name">

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原文由 Mohd Zaid 发布，翻译遵循 CC BY-SA 4.0 许可协议