/** * 透明度可變的標(biāo)題欄 *  * @author Zhao KaiQiang *  * @Time 2014-6-20 上午11:46:42 */public class MainActivity extends Activity implements OnScrollListener { private XListView listView; // 標(biāo)題欄的布局 private RelativeLayout rl_title; // ListView的頭布局 private View headerView; // 頭布局的高度 private int headerHeight; private LayoutInflater inflater; private Handler handler = new Handler(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); rl_title = (RelativeLayout) findViewById(R.id.rl_title); listView = (XListView) findViewById(R.id.list); rl_title.getBackground().setAlpha(0); inflater = LayoutInflater.from(this); headerView = inflater.inflate(R.layout.header_listview, null); // 添加頭布局 listView.addHeaderView(headerView); listView.setAdapter(new MyAdapter()); // 設(shè)置滾動監(jiān)聽 listView.setOnScrollListener(this); // 設(shè)置可以刷新與加載更多 listView.setPullLoadEnable(true); listView.setPullRefreshEnable(true); listView.setXListViewListener(new IXListViewListener() {  @Override  public void onRefresh() {  // 單純的模擬刷新過程  handler.postDelayed(new Runnable() {   @Override   public void run() {   listView.stopRefresh();   }  }, 500);  }  @Override  public void onLoadMore() {  // 單純的模擬加載過程  handler.postDelayed(new Runnable() {   @Override   public void run() {   listView.stopLoadMore();   }  }, 500);  } }); } // 自定義適配器 private class MyAdapter extends BaseAdapter { // 默認(rèn)顯示10個item @Override public int getCount() {  return 10; } @Override public Object getItem(int position) {  return position; } @Override public long getItemId(int position) {  return position; } @Override public View getView(int position, View convertView, ViewGroup parent) {  if (convertView == null) {  convertView = inflater.inflate(R.layout.item_list, null);  }  return convertView; } } @Override public void onScrollStateChanged(AbsListView view, int scrollState) { } // 最重要的方法，標(biāo)題欄的透明度變化在這個方法實(shí)現(xiàn) @Override public void onScroll(AbsListView listView, int firstVisibleItem,  int visibleItemCount, int totalItemCount) { // 判斷當(dāng)前最上面顯示的是不是頭布局，因?yàn)閄listview有刷新控件，所以頭布局的位置是1，即第二個 if (firstVisibleItem == 1) {  // 獲取頭布局  View view = listView.getChildAt(0);  if (view != null) {  // 獲取頭布局現(xiàn)在的最上部的位置的相反數(shù)  int top = -view.getTop();  // 獲取頭布局的高度  headerHeight = view.getHeight();  // 滿足這個條件的時(shí)候，是頭布局在XListview的最上面第一個控件的時(shí)候，只有這個時(shí)候，我們才調(diào)整透明度  if (top <= headerHeight && top >= 0) {   // 獲取當(dāng)前位置占頭布局高度的百分比   float f = (float) top / (float) headerHeight;   rl_title.getBackground().setAlpha((int) (f * 255));   // 通知標(biāo)題欄刷新顯示   rl_title.invalidate();  }  } } else if (firstVisibleItem > 1) {  rl_title.getBackground().setAlpha(255); } else {  rl_title.getBackground().setAlpha(0); } }}