android ViewSwitcher的用法介紹

ViewSwitcher 的作用簡單來說就是：在兩個視圖間轉換時顯示動畫

它的兩個子類應該很熟悉，ImageSwitcher：轉換圖片時增加動畫效果;TextSwitcher：轉換文字時增加動畫效果;其實例見apidemos中ImageSwitcher實例和TextSwitcher實例

但不要忽略ViewSwicher,在一些場合還是很有用的

在android裡視圖切換是一個很常見的需求，比如說加載view和後台背景，當後台加載數據時，loding view顯示，數據View隱藏，加載完成，反向此過程。使用ViewSwicher提供了簡單的邏輯，產生更可讀的代碼。

舉個最常見的例子，模擬點擊LoadMoreItems按鈕或得更多數據。

1 2 3 4 5 6 7 8 9 10 11 12 "1.0" encoding="utf-8"?> "http://schemas.android.com/apk/res/android" android:id="@+id/btn_loadmorecontacts" android:text="Load More Items" android:layout_width="fill_parent" android:layout_height="wrap_content" android:textAppearance="?android:attr/textAppearanceLarge" android:minHeight="?android:attr/listPreferredItemHeight" android:textColor="#FFFFFF" android:background="@android:drawable/list_selector_background" android:clickable="true" android:onClick="onClick" />

大致是這樣子

 

 

 

加載中視圖：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 "1.0" encoding="utf-8"?> "http://schemas.android.com/apk/res/android" android:layout_width="wrap_content" android:layout_height="wrap_content" android:gravity="center_horizontal" android:minHeight="?android:attr/listPreferredItemHeight"> android:id="@+id/progressbar" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerVertical="true" /> android:text="Loading…" android:textAppearance="?android:attr/textAppearanceLarge" android:layout_height="wrap_content" android:layout_width="wrap_content" android:layout_toRightOf="@+id/progressbar" android:layout_centerVertical="true" android:gravity="center" android:padding="10dip" android:textColor="#FFFFFF" />

 

 

 

 

 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 public class ViewSwitcherExample extends ListActivity implements OnClickListener { //sample list items static final String[] ITEMS = new String[] { "List Item 1", "List Item 2", "List Item 3", "List Item 4", "List Item 5", "List Item 6", "List Item 7", "List Item 8", "List Item 9", "List Item 10" }; //the ViewSwitcher private ViewSwitcher switcher; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //no window title requestWindowFeature(Window.FEATURE_NO_TITLE); //create the ViewSwitcher in the current context switcher = new ViewSwitcher(this); //footer Button: see XML1 Button footer = (Button)View.inflate(this, R.layout.btn_loadmore, null); //progress View: see XML2 View progress = View.inflate(this, R.layout.loading_footer, null); //add the views (first added will show first) switcher.addView(footer); switcher.addView(progress); //add the ViewSwitcher to the footer getListView().addFooterView(switcher); //add items to the ListView setListAdapter(new ArrayAdapter(this, android.R.layout.simple_list_item_1, ITEMS)); } @Override /* Load More Button Was Clicked */ public void onClick(View arg0) { //first view is showing, show the second progress view switcher.showNext(); //and start background work new getMoreItems().execute(); } /** Background Task To Get More Items**/ private class getMoreItems extends AsyncTask { @Override protected Object doInBackground(Void… params) { //code to add more items //... try { Thread.sleep(3000); //only to demonstrate } catch (InterruptedException e) { e.printStackTrace(); } return null; } @Override /* Background Task is Done */ protected void onPostExecute(Object result) { //go back to the first view switcher.showPrevious(); //update the ListView } } }

當然你也可以使用xml形式構造ViewSwicher,這裡加上了系統自帶的切換效果@android:anim/slide_in_left和@android:anim/slide_out_right

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 "1.0"encoding="utf-8"?> "http://schemas.android.com/apk/res/android" android:id="@+id/profileSwitcher" android:layout_width="fill_parent" android:layout_height="fill_parent" android:inAnimation="@android:anim/slide_in_left" android:outAnimation="@android:anim/slide_out_right"> android:layout_width="wrap_content" android:layout_height="wrap_content"> android:id="@+id/progressbar" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerVertical="true"/> android:text="Loading…" android:layout_height="wrap_content" android:layout_width="wrap_content" android:layout_toRightOf="@+id/progressbar" android:gravity="center"/> android:layout_width="wrap_content" android:layout_height="wrap_content" android:gravity="center_horizontal"> android:text="Finished!" android:layout_height="wrap_content" android:layout_width="wrap_content" android:layout_centerVertical="true"/>