无法在/mnt/sdcard中创建文件夹

Question

我认为我已经做好了一切准备，首先创建一个文件夹，以便稍后在我的应用程序中进行写入，但似乎并没有起作用。有什么线索能告诉我我失败了吗？

它正确地尝试创建 /mnt/sdcard/gradebook

我在清单中使用了uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"。我正在真实设备（三星Galaxy S）上运行，并且在连接到计算机时没有使用sd卡作为存储。

    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;
        Toast.makeText(this,"This Application needs a writable external storage (sdcard).",Toast.LENGTH_SHORT).show();
        finish();
    } 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;
        Toast.makeText(this,"This Application needs a mounted external storage (sdcard).",Toast.LENGTH_SHORT).show();
        finish();

    }


    File folder = new File(Environment.getExternalStorageDirectory () + "/gradeBook");
    boolean success = false;
    if(!folder.exists()){
         success = folder.mkdir();
    }
    if (!success) {
        Log.e("FILE", "can't create " + folder);
    }
    else 
    {
        Log.i("FILE", "directory is created"); 
    }

这是清单文件。

<?xml version="1.0" encoding="utf-8"?>
  <manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.ulsanonline.gradebook" 
    android:versionName="@string/version" 
    android:installLocation="auto" 
    android:versionCode="2">
    <uses-sdk android:minSdkVersion="8"></uses-sdk> 
    <application 
        android:icon="@drawable/icon" 
        android:debuggable="true" 
        android:persistent="false" 
        android:hasCode="true"
        android:minSdkVersion="8">
        <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
        <uses-permission android:name="android.permission.CAMERA" />
        <activity 
            android:name=".CourseWork" 
            android:label="@string/app_name" 
            android:screenOrientation="portrait">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

- Martin

---

你的电脑上是否挂载了磁盘？如果你试图向连接到计算机的磁盘写入数据，你将会收到权限被拒绝的错误提示。 - ceejayoz

Answer 1

uses-permission必须直接放置在<manifest>标签中，因此应该这样写：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.ulsanonline.gradebook" 
    android:versionName="@string/version" 
    android:installLocation="auto" 
    android:versionCode="2">
    <uses-sdk android:minSdkVersion="8"></uses-sdk> 
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.CAMERA" />
    <application 
        android:icon="@drawable/icon" 
        android:debuggable="true" 
        android:persistent="false"

- ayublin

---

成功了！非常感谢……但是相机放置的位置没有引起问题，这是怎么回事？ - Martin

也许是因为我的应用程序不控制相机，只是将其传递给一个未命名的活动来拍照。我使用的是Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);而不是我的软件包中的任何内容。 - Martin

Answer 2

试试这个，

//Declare a string 

String NewFolder = "/myNewFolder";
String extStorageDirectory;

//external storage directory path
    extStorageDirectory = Environment.getExternalStorageDirectory().toString();    
//creating a new folder
File mkTarDir=new File(extStorageDirectory + NewFolder);
  mkTarDir.mkdir();
//path to save a image              
File file = new File(extStorageDirectory + NewFolder ,"myimage"+String.valueOf(System.currentTimeMillis()) + ".PNG");

- yeshbourne