android 外部存储创建文件夹总是返回false的问题

来源：互联网发布：黑龙江优化发展环境编辑：程序博客网时间：2024/05/22 10:34

项目需要在外部存储中新建立文件夹，部分代码如下：

if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
    File file=new File(Environment.getExternalStorageDirectory(),"Demo");//路径是/mnt/sdcard
    boolean isCreate=file.mkdir();
   Log.d("TAG",”isCreate="+isCreate);
}

manifest.xml中声明了权限如下：
<user-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
在adb shell中查看所有文件：
D:\workspace\ZZTDemo>adb shell
error: more than one device/emulatorD:\workspace\ZZTDemo>adb shell
root@android:/ # cd sdcard
root@android:/sdcard # ls -al
drwxrwxr-x system sdcard_rw 2016-08-24 04:14 .BD_SAPI_CACHE
drwxrwxr-x system sdcard_rw 2016-12-05 01:29 .DataStorage
drwxrwxr-x system sdcard_rw 2016-10-24 10:23 .UTSystemConfig
d--------- root root 2016-12-06 00:37 .android_secure
drwxrwxr-x system sdcard_rw 2011-01-02 10:36 Alarms
drwxrwxr-x system sdcard_rw 2011-01-02 12:05 Android
drwxrwxr-x system sdcard_rw 2016-12-05 01:29 BaiduAsbe76b54f
drwxrwxr-x system sdcard_rw 2016-12-05 09:01 CloudDrive
drwxrwxr-x system sdcard_rw 2011-01-02 10:36 DCIM
drwxrwxr-x system sdcard_rw 2016-08-24 04:18 Download
-rwxrwxr-x system sdcard_rw 282255 2014-08-25 15:46 EMserialportV2.0.apk
-rwxrwxr-x system sdcard_rw 791741 2014-08-18 15:08 Exhibition.apk
drwxrwxr-x system sdcard_rw 2011-01-02 10:35 LOST.DIR
drwxrwxr-x system sdcard_rw 2011-01-02 10:36 Movies
drwxrwxr-x system sdcard_rw 2011-01-02 10:36 Music
drwxrwxr-x system sdcard_rw 2011-01-02 10:36 Notifications
drwxrwxr-x system sdcard_rw 2011-01-02 10:36 Pictures
drwxrwxr-x system sdcard_rw 2011-01-02 10:36 Podcasts
drwxrwxr-x system sdcard_rw 2011-01-02 10:36 Ringtones
drwxrwxr-x system sdcard_rw 2016-09-14 16:19 System Volume Information
-rwxrwxr-x system sdcard_rw 1713377 2016-10-19 20:14 app-debug.apk
drwxrwxr-x system sdcard_rw 2016-08-24 04:14 backups
drwxrwxr-x system sdcard_rw 2016-08-24 04:19 baidu
drwxrwxr-x system sdcard_rw 2016-07-28 08:49 bluetooth
-rwxrwxr-x system sdcard_rw 0 2016-08-24 04:14 com.baidu.appsearch.log
-rwxrwxr-x system sdcard_rw 0 2016-12-06 00:37 com.baidu.appsearch.log.lck
-rwxrwxr-x system sdcard_rw 7043511 2016-09-14 20:17 data.txt
-rwxrwxr-x system sdcard_rw 11415 2016-09-14 18:49 data2.txt
drwxrwxr-x system sdcard_rw 2011-01-02 10:38 external_sdcard
drwxrwxr-x system sdcard_rw 2016-12-05 08:34 zzt
可以看到文件夹并未创建，打印的Log中显示mkdir()返回值一直是false。
使用context.getExternalFilesDir(null)创建文件夹也会返回false。

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