Android 文件写入只读文件系统警告
我正在尝试使用 FileOutputStream 和 OutputStreamWriter 写入文件，但我不断收到只读警告。
这是我正在使用的代码
FileOutputStream fw = new FileOutputStream((trackName.replaceAll(" ", ""))+".gpx", true);
OutputStreamWriter osw = new OutputStreamWriter(fw);
osw.write(XML_HEADER+"\n");
osw.write(TAG_GPX+"\n");
writeTrackPoints(trackName, osw, locations, time, trackDescp);
writeWayPoints(osw, locations,time);
osw.flush();
osw.close();
，并且 Logcat 输出是
java.io.FileNotFoundException: /test.gpx (Read-only file system)
at org.apache.harmony.luni.platform.OSFileSystem.openImpl(Native Method)
at org.apache.harmony.luni.platform.OSFileSystem.open(OSFileSystem.java:152)
at java.io.FileOutputStream.<init>(FileOutputStream.java:97)
at java.io.FileOutputStream.<init>(FileOutputStream.java:168)
at java.io.FileOutputStream.<init>(FileOutputStream.java:147)
at com.fyp.run_race.GPXFileWriter.<init>(GPXFileWriter.java:25)
at com.fyp.run_race.GPSTrackDetails$1.onClick(GPSTrackDetails.java:58)
at android.view.View.performClick(View.java:2408)
at android.view.View$PerformClick.run(View.java:8816)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4627)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
at dalvik.system.NativeStart.main(Native Method)
我确定问题到底是什么。
I'm trying to write a file using the FileOutputStreamand OutputStreamWriterbut I keep getting a read only warning.
Here is the code that I am using
FileOutputStream fw = new FileOutputStream((trackName.replaceAll(" ", ""))+".gpx", true);
OutputStreamWriter osw = new OutputStreamWriter(fw);
osw.write(XML_HEADER+"\n");
osw.write(TAG_GPX+"\n");
writeTrackPoints(trackName, osw, locations, time, trackDescp);
writeWayPoints(osw, locations,time);
osw.flush();
osw.close();
And the Logcatoutput is
java.io.FileNotFoundException: /test.gpx (Read-only file system)
at org.apache.harmony.luni.platform.OSFileSystem.openImpl(Native Method)
at org.apache.harmony.luni.platform.OSFileSystem.open(OSFileSystem.java:152)
at java.io.FileOutputStream.<init>(FileOutputStream.java:97)
at java.io.FileOutputStream.<init>(FileOutputStream.java:168)
at java.io.FileOutputStream.<init>(FileOutputStream.java:147)
at com.fyp.run_race.GPXFileWriter.<init>(GPXFileWriter.java:25)
at com.fyp.run_race.GPSTrackDetails$1.onClick(GPSTrackDetails.java:58)
at android.view.View.performClick(View.java:2408)
at android.view.View$PerformClick.run(View.java:8816)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4627)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
at dalvik.system.NativeStart.main(Native Method)
I ament sure what the problem is really.
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评论（3）
不知道为什么普拉蒂克的评论被否决了——他是对的，因为你需要写入外部存储的权限。假设这就是你想要写的地方。
Devconsole 也是对的；您不能只写入任意文件名，大多数文件系统都被锁定且只读。
要写入外部存储（sdcard）中的任意位置，请使用 getExternalStorageDirectory() 获取外部存储的根目录。另请使用 getExternalStorageState() 确认外部存储存储实际上可用。
不要将文件放在外部存储的根目录下；将它们放在子目录中，以防止根目录变得过于混乱。 （编辑：有些 Android 实现无论如何也不会让你这样做。）
使用 getExternalFilesDir() 获取外部存储中名义上对您的应用程序私有的位置。 （API 8 中的新增功能）
使用 getFilesDir() 获取 /data/ 下可以写入应用程序私有文件的位置。这不在外部存储上，因此空间紧张；不要在这里写入大文件。
另请参阅：
Dunno why Pratik's comment was downvoted -- he's right in that you'll want the permission to write to external storage. Assuming that's where you want to write.
Devconsole is also right; you can't just write to any arbitrary filename, most of the file system is locked down and read-only.
To write to an arbitrary location in external storage (sdcard), use getExternalStorageDirectory() for the root of external storage. Also use getExternalStorageState() to confirm that external storage is actually available.
Don't place files in the root of external storage; place them in a subdirectory to prevent the root from becoming too cluttered. (Edit: and some Android implementations won't let you do this anyway.)
Use getExternalFilesDir() to get a location in external storage that's nominally private to your application. (New in API 8)
Use getFilesDir() to get a location under /data/ where you can write application-private files. This isn't on external storage, so space is tight; don't write big files here.
See also:
您只能将文件写入内部存储（设备内存）或外部存储（SD 卡），请参阅 http://developer.android.com/guide/topics/data/data-storage.html。简单地打开具有任意文件名的 FileOutputStream 是行不通的，因为该文件系统是只读的。
You can write files only to Internal Storage (device memory) or External Storage (the SD card), see http://developer.android.com/guide/topics/data/data-storage.html. Simply opening a FileOutputStream with an arbitrary file name won't work since that file system is read-only.
只需在清单中授予许可
just give permission in manifest