Android 環境變量訪問類

摘自：http://developer.android.com/reference/android/os/Environment.html

 

Constants
String	MEDIA_BAD_REMOVAL	在沒有掛載前存儲媒體已經被移除。
String	MEDIA_CHECKING	正在檢查存儲媒體。
String	MEDIA_MOUNTED	存儲媒體已經掛載，並且掛載點可讀/寫。
String	MEDIA_MOUNTED_READ_ONLY	存儲媒體已經掛載，掛載點只讀。
String	MEDIA_NOFS	存儲媒體是空白或是不支持的文件系統。
String	MEDIA_REMOVED	存儲媒體被移除。
String	MEDIA_SHARED	存儲媒體正在通過USB共享。
String	MEDIA_UNMOUNTABLE	存儲媒體無法掛載。
String	MEDIA_UNMOUNTED	存儲媒體沒有掛載。

 

Fields
public static String	DIRECTORY_ALARMS	系統提醒鈴聲存放的標準目錄。
public static String	DIRECTORY_DCIM	相機拍攝照片和視頻的標準目錄。
public static String	DIRECTORY_DOWNLOADS	下載的標準目錄。
public static String	DIRECTORY_MOVIES	電影存放的標準目錄。
public static String	DIRECTORY_MUSIC	音樂存放的標準目錄。
public static String	DIRECTORY_NOTIFICATIONS	系統通知鈴聲存放的標準目錄。
public static String	DIRECTORY_PICTURES	圖片存放的標準目錄。
public static String	DIRECTORY_PODCASTS	系統廣播存放的標準目錄。
public static String	DIRECTORY_RINGTONES	系統鈴聲存放的標準目錄。

相關環境變量的值在init.${ro.hardware}.rc 中設置。

 

Public Methods
static File	getDataDirectory() 獲得android data的目錄。
static File	getDownloadCacheDirectory() 獲得下載緩存目錄。
static File	getExternalStorageDirectory() 或者外部存儲媒體目錄。
static File	getExternalStoragePublicDirectory(String type) Get a top-level public external storage directory for placing files of a particular type.
static String	getExternalStorageState() 獲得當前外部儲存媒體的狀態。
static File	getRootDirectory() 獲得android的跟目錄。

public static File getExternalStoragePublicDirectory (String type)
Since: API Level 8
Get a top-level public external storage directory for placing files of a particular type. This is where the user will typically place and manage their own files, so you should be careful about what you put here to ensure you don't erase their files or get in the way of their own organization.
Here is an example of typical code to manipulate a picture on the public external storage:
void createExternalStoragePublicPicture() {
    // Create a path where we will place our picture in the user's
    // public pictures directory.  Note that you should be careful about
    // what you place here, since the user often manages these files.  For
    // pictures and other media owned by the application, consider
    // Context.getExternalMediaDir().
    File path = Environment.getExternalStoragePublicDirectory(
            Environment.DIRECTORY_PICTURES);
    File file = new File(path, "DemoPicture.jpg");

    try {
        // Make sure the Pictures directory exists.
        path.mkdirs();

        // Very simple code to copy a picture from the application's
        // resource into the external file.  Note that this code does
        // no error checking, and assumes the picture is small (does not
        // try to copy it in chunks).  Note that if external storage is
        // not currently mounted this will silently fail.
        InputStream is = getResources().openRawResource(R.drawable.balloons);
        OutputStream os = new FileOutputStream(file);
        byte[] data = new byte[is.available()];
        is.read(data);
        os.write(data);
        is.close();
        os.close();

        // Tell the media scanner about the new file so that it is // 這一步非常重要！！
        // immediately available to the user.
        MediaScannerConnection.scanFile(this,
                new String[] { file.toString() }, null,
                new MediaScannerConnection.OnScanCompletedListener() {
            public void onScanCompleted(String path, Uri uri) {
                Log.i("ExternalStorage", "Scanned " + path + ":");
                Log.i("ExternalStorage", "-> uri=" + uri);
            }
        });
    } catch (IOException e) {
        // Unable to create file, likely because external storage is
        // not currently mounted.
        Log.w("ExternalStorage", "Error writing " + file, e);
    }
}

void deleteExternalStoragePublicPicture() {
    // Create a path where we will place our picture in the user's
    // public pictures directory and delete the file.  If external
    // storage is not currently mounted this will fail.
    File path = Environment.getExternalStoragePublicDirectory(
            Environment.DIRECTORY_PICTURES);
    File file = new File(path, "DemoPicture.jpg");
    file.delete();
}

boolean hasExternalStoragePublicPicture() {
    // Create a path where we will place our picture in the user's
    // public pictures directory and check if the file exists.  If
    // external storage is not currently mounted this will think the
    // picture doesn't exist.
    File path = Environment.getExternalStoragePublicDirectory(
            Environment.DIRECTORY_PICTURES);
    File file = new File(path, "DemoPicture.jpg");
    return file.exists();
}

 

Parameters

type	The type of storage directory to return. Should be one ofDIRECTORY_MUSIC,DIRECTORY_PODCASTS,DIRECTORY_RINGTONES,DIRECTORY_ALARMS,DIRECTORY_NOTIFICATIONS,DIRECTORY_PICTURES,DIRECTORY_MOVIES,DIRECTORY_DOWNLOADS, orDIRECTORY_DCIM. May not be null.

Returns

• Returns the File path for the directory. Note that this directory may not yet exist, so you must make sure it exists before using it such as withFile.mkdirs().

示例：http://www.cnblogs.com/mengdd/p/3742623.html