怎么在Android应用中添加一个文件管理功能

<&#63;xml version="1.0" encoding="utf-8"&#63;><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <HorizontalScrollView android:layout_width="match_parent" android:layout_height="wrap_content" android:scrollbars="none"> <LinearLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" android:id="@+id/lyPath"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:textAppearance="&#63;android:textAppearance" android:text="@string/txt_path_now"/> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:textAppearance="&#63;android:textAppearance" android:text="mnt/sdcard" android:id="@+id/txtPath"/> </LinearLayout> </HorizontalScrollView> <View android:layout_width="match_parent" android:layout_height="1dp" android:background="@android:color/darker_gray"/> <LinearLayout android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="1"> <ListView android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/folderList"/> </LinearLayout></LinearLayout>