Android无法在SD卡上执行mkdir（）

Question

我有一些代码可以在SD卡上创建/获取文件夹：

if( hasSDCard() ){

        UUID uniqueFileName = UUID.randomUUID();

        mediaStorageDir = new File(
                getExternalImageStoragePath(),
                "MyApp");

        if ( ! mediaStorageDir.exists() ){

            if( ! mediaStorageDir.mkdirs() ){

                MyLogger.Error("Create image directory FAILED. path: " + mediaStorageDir.getPath());

                return null;
            }
        }

并且我已经在清单文件中注册了权限：

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

但是当我运行它时，它会打印：

Create image directory FAILED. path: /storage/emulated/0/Pictures/MyApp

我想知道为什么会这样吗？

===更新===

我已经尝试了所有这些：

/**
 * get external storage directory path for image
 * @return
 */
public static String getExternalImageStoragePath(){

    String strPath = "";

    if(hasSDCard()){
        //strPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getPath();
        //strPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath();
        //strPath = Environment.getExternalStorageDirectory().getPath();
        strPath = Environment.getExternalStorageDirectory().getAbsolutePath();
    }

    return strPath;
}

但是他们的行为完全一样...

===更新2 ===

我正在测试Nexus5。我看到了这篇文章在Eclipse中找不到Nexus 7的storage / emulated / 0 /文件夹可能有问题吗？

===更新3 ===

>> adb shell ls -l /storage/
dr-xr-xr-x root     root              1970-01-24 23:48 emulated
lrwxrwxrwx root     root              1970-01-24 23:48 sdcard0 -> /storage/emulated/legacy

>> adb shell ls -l /storage/emulated/0/Pictures/
/storage/emulated/0/Pictures/: No such file or directory

===更新4 ===

这是我的hasSD()方法：

public static boolean hasSDCard(){
    boolean fHasSDCard = false;

    if(Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())){
        fHasSDCard = true;
    }

    return fHasSDCard;
}

Answer 1

编辑：您拼错了您的权限（您有STOREAGE，而正确的是STORAGE）

更改

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

至：

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

除非您尚未在hasSDCard（）中进行此操作，否则请检查您的外部媒体是否完全可用。 正如文档所说：

在使用外部存储进行任何操作之前，应始终调用getExternalStorageState（）来检查介质是否可用。 介质可能已安装到计算机上，丢失，只读或处于其他某种状态。

他们提供了一个示例：

boolean mExternalStorageAvailable = false;
boolean mExternalStorageWriteable = false;
String state = Environment.getExternalStorageState();

if (Environment.MEDIA_MOUNTED.equals(state)) {
    // We can read and write the media
    mExternalStorageAvailable = mExternalStorageWriteable = true;
} else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
    // We can only read the media
    mExternalStorageAvailable = true;
    mExternalStorageWriteable = false;
} else {
    // Something else is wrong. It may be one of many other states, but all we need
    //  to know is we can neither read nor write
    mExternalStorageAvailable = mExternalStorageWriteable = false;
}

Answer 2

// try this
File mediaStorageDir = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/" + "MyApp" + "/");
if (!mediaStorageDir.exists()) {
      mediaStorageDir.mkdirs();
}

mediaStorageDir.getAbsolutePath()

Answer 3

尝试这个：

mediaStorageDir = new File(
            Environment.getExternalStorageDirectory().getAbsolutePath(),
            "MyApp");

Answer 4

这就是我正在做的事情，对我有用

File path = Environment.getExternalStorageDirectory();
String save_path = path.toString() + "/MyApp/";
File newFile=new File(save_path );
newFile.mkdirs();