android sdcard信息获取

手机存储都有两种，一种是 手机自带的存储，称为internal storage,另外一种用户额外插入的存储，称为removable storage (也就是外置sdcard的部分).

removable storage 的路径一般是 storage/emulated/0/Android/data/com.example.storagetest/files/alarm

internal storage 也有一部分称为 external (也就是内置sdcard的部分) 的,这部分的路径为  /storage/emulated/0

获取内置sdcard路径方法

　　　　通过 Context.get....dir或者 Environment.get...dir(Environment.getExternalStorageDirectory())去获取

获取外置sdcard路径方法

　　　　1.String extSdcardPath = System.getenv("SECONDARY_STORAGE");

　　　　2.通过StorageManager  来获取。

StorageManager mStorageManager = (StorageManager) mContext.getSystemService(Context.STORAGE_SERVICE);
        Class<?> storageVolumeClazz = null;
        try {
            storageVolumeClazz = Class.forName("android.os.storage.StorageVolume");
            Method getVolumeList = mStorageManager.getClass().getMethod("getVolumeList");
            Method getPath = storageVolumeClazz.getMethod("getPath");
            Method isRemovable = storageVolumeClazz.getMethod("isRemovable");
            Object result = getVolumeList.invoke(mStorageManager);
            final int length = Array.getLength(result);
            for (int i = 0; i < length; i++) {
                Object storageVolumeElement = Array.get(result, i);
                String path = (String) getPath.invoke(storageVolumeElement);//如果有外置sdcard，那么 sdcard1 就是外置的了。
                boolean removable = (Boolean) isRemovable.invoke(storageVolumeElement);
                if (is_removale == removable) {
                    return path;
                }
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
        return null;