java_io_FileNotFoundException

问题分析

文件未找到或无权限时抛出此类异常。

解决方案

文件未找到或无权限时,请确认文件路径文件存在,添加所需访问权限,确保文件存在的情况下进行读写,并增加try catch块做异常处理。

代码示例

增加读写外部存储上的文件权限:

<uses-permissionandroid:name="android.permission.READ_EXTERNAL_STORAGE"></uses-permission>
<uses-permissionandroid:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>

创建文件,增加读写权限并catch exception。

File extDir = Environment.getExternalStorageDirectory();
String filename = "file.txt";
File fullFilename = new File(extDir, filename);
try {
if(!fullFilename.exists()){
        fullFilename.createNewFile();
        fullFilename.setWritable(Boolean.TRUE);
                // 写文件操作
    }
    else{
        // 读文件操作
    }
} catch (IOException e) {
    e.printStackTrace();
}

示例:

java.io.FileNotFoundException: /proc/mtprof/status: open failed: ENOENT (No such file or directory)
    at libcore.io.IoBridge.open(IoBridge.java:496)
    at java.io.FileInputStream.<init>(FileInputStream.java:76)
    at java.io.FileInputStream.<init>(FileInputStream.java:103)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1494)
    at android.os.Handler.dispatchMessage(Handler.java:111)
    at android.os.Looper.loop(Looper.java:194)
    at android.app.ActivityThread.main(ActivityThread.java:5692)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:959)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:754)
Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
    at libcore.io.Posix.open(Native Method)
    at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
    at libcore.io.IoBridge.open(IoBridge.java:482)
    ... 10 more

异常导致应用无法启动。日志如下:

10-20 09:43:08.073   820   820 E WifiTrafficPoller: TRAFFIC_STATS_POLL true Token 1138 num clients 12
10-20 09:43:08.074   820   820 E WifiTrafficPoller:  packet count Tx=237196 Rx=493756
10-20 09:43:08.365   820   842 W BroadcastQueue: Skipping deliver [background] BroadcastRecord{9a089ad u-1 android.net.conn.CONNECTIVITY_CHANGE} to ReceiverList{2c1b84e2 23189 (unknown name)/2000/u-1 remote:2663fdd7}: process crashing
10-20 09:43:08.401 23079 23079 E ActivityThread: mtprof entry can not be found
10-20 09:43:08.401 23079 23079 E ActivityThread: java.io.FileNotFoundException: /proc/mtprof/status: open failed: ENOENT (No such file or directory)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at libcore.io.IoBridge.open(IoBridge.java:496)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at java.io.FileInputStream.<init>(FileInputStream.java:76)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at java.io.FileInputStream.<init>(FileInputStream.java:103)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1494)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at android.os.Handler.dispatchMessage(Handler.java:111)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at android.os.Looper.loop(Looper.java:194)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at android.app.ActivityThread.main(ActivityThread.java:5692)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at java.lang.reflect.Method.invoke(Native Method)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at java.lang.reflect.Method.invoke(Method.java:372)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:959)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:754)
10-20 09:43:08.401 23079 23079 E ActivityThread: Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at libcore.io.Posix.open(Native Method)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
10-20 09:43:08.401 23079 23079 E ActivityThread:     at libcore.io.IoBridge.open(IoBridge.java:482)
10-20 09:43:08.401 23079 23079 E ActivityThread:     ... 10 more
10-20 09:43:08.415 23079 23079 W Launcher: setApplicationContext called twice! 
10-20 09:43:08.422 23079 23079 E Fatal exception: :java.lang.RuntimeException: Unable to start activity ComponentInfo{}: java.io.IOException: broken file descriptor
10-20 09:43:08.422 23079 23079 W System.err: java.lang.RuntimeException: Unable to start activity ComponentInfo{}: java.io.IOException: broken file descriptor
10-20 09:43:08.422 23079 23079 W System.err:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2581)
10-20 09:43:08.422 23079 23079 W System.err:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2656)
10-20 09:43:08.422 23079 23079 W System.err:     at android.app.ActivityThread.access$800(ActivityThread.java:178)
10-20 09:43:08.423 23079 23079 W System.err:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1512)
10-20 09:43:08.423 23079 23079 W System.err:     at android.os.Handler.dispatchMessage(Handler.java:111)
10-20 09:43:08.423 23079 23079 W System.err:     at android.os.Looper.loop(Looper.java:194)
10-20 09:43:08.423 23079 23079 W System.err:     at android.app.ActivityThread.main(ActivityThread.java:5692)
10-20 09:43:08.423 23079 23079 W System.err:     at java.lang.reflect.Method.invoke(Native Method)
10-20 09:43:08.423 23079 23079 W System.err:     at java.lang.reflect.Method.invoke(Method.java:372)
10-20 09:43:08.423 23079 23079 W System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:959)
10-20 09:43:08.423 23079 23079 W System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:754)
10-20 09:43:08.423 23079 23079 W System.err: Caused by: java.io.IOException: broken file descriptor
10-20 09:43:08.423 23079 23079 W System.err:     at android.graphics.BitmapFactory.nativeDecodeFileDescriptor(Native Method)
10-20 09:43:08.423 23079 23079 W System.err:     at android.graphics.BitmapFactory.decodeFileDescriptor(BitmapFactory.java:714)
10-20 09:43:08.423 23079 23079 W System.err:     at android.app.WallpaperManager$Globals.getCurrentWallpaperLocked(WallpaperManager.java:308)
10-20 09:43:08.423 23079 23079 W System.err:     at android.app.WallpaperManager$Globals.peekWallpaperBitmap(WallpaperManager.java:270)
10-20 09:43:08.423 23079 23079 W System.err:     at android.app.WallpaperManager.getDrawable(WallpaperManager.java:413)

更换手机桌面应用布局界面时调用native方法decodeFileDescriptor读取文件/proc/stprof/status抛出了异常未捕获导致进程崩溃,建议按照示例一判断文件是否存在并对异常进行捕获处理。

参考文献

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