如何在Android中的SDCard中创建文件夹

Question

我想在我的sdcard中制作文件夹，我在下面使用的代码：

public class Screen extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.welcome);

        operateOnFirstUsage();
    }

    private void operateOnFirstUsage() {

        String state = Environment.getExternalStorageState();
        Log.d("Media State", state);

        if (Environment.MEDIA_MOUNTED.equals(state)) {
            File appDirectory = new File(
                    Environment.getExternalStorageDirectory().getAbsolutePath() + "/MyApp/");

            Log.d("appDirectroyExist", appDirectory.exists() + "");
            if (!appDirectory.exists()) 
                Log.d("appDir created: ", appDirectory.mkdir() + "");

            File dbDirectory = new File(
                    Environment.getExternalStorageDirectory().getAbsolutePath() + "/MyApp/Database/");

            Log.d("dbDirectroyExist", dbDirectory.exists() + "");
            if (!dbDirectory.exists())
                Log.d("dbDir created: ", dbDirectory.mkdirs() + "");


            File themesDirectory = new File(
                    Environment.getExternalStorageDirectory().getAbsolutePath() + "/MyApp/Themes/");
            Log.d("themesDirectroyExist", themesDirectory.exists() + "");
            if (!themesDirectory.exists()) 
                Log.d("themesDir created: ", themesDirectory.mkdirs() + "");

        }
    }
}

.

此外，我已设置SDCard Write权限：

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

.

我已经运行了多次应用程序，每次我得到logcat输出时都会运行：

01-09 21:38:13.701: D/Media State(15363): mounted
01-09 21:38:13.701: D/appDirectroyExist(15363): false
01-09 21:38:13.701: D/appDir created:(15363): false
01-09 21:38:13.701: D/dbDirectroyExist(15363): false
01-09 21:38:13.701: D/dbDir created:(15363): false
01-09 21:38:13.701: D/themesDirectroyExist(15363): false
01-09 21:38:13.701: D/themesDir created:(15363): false

.

我已经阅读了类似的问题，但没有什么有用的。我该怎么办才能获得代码运行？我的问题是什么？

Answer 1

我不知道为什么应用程序采取行动，但最后我通过删除和重置android清单文件中的sdcard写权限来克服此问题。谢谢你们所有人的帮助，并为您的时间而道歉。

Answer 2

编辑

试试：

File mydir = new File(Environment.getExternalStorageDirectory() + "/mydir/");
if(!mydir.exists())
    mydir.mkdirs();
else
    Log.d("error", "dir. already exists");

.

并重新检查权限

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

.

Answer 3

这是我在图片文件夹OD SDCard中创建文件夹MyDir的方式：

File mediaStorageDir =  new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),"MyDir");
mediaStorageDir.mkdirs();

.

Answer 4

以这种方式：

File file=new File(Environment.getExternalStorageDirectory() + File.separator +"MyApp/");
file.mkdirs();

.

Answer 5

试试这个代码:)，它简单。

        String fileName = "CallHistory.pdf";

        // create a File object for the parent directory
        File PDF_Directory = new File("/sdcard/MOBstate/");

        // have the object build the directory structure, if needed.          
        PDF_Directory.mkdirs();

        // create a File object for the output file           
         File outputFile = new File(PDF_Directory, fileName);

        // now attach the OutputStream to the file object, instead of a ring representation
         FileOutputStream fos = new FileOutputStream(outputFile);

.