大家好，又见面了，我是全栈君。
近期在项目中须要用到下拉菜单。公司比較推崇美团的下拉菜单，于是要实现该功能。想着。这个功能应该是一个常常会用到的。于是何不写一个帮助类，仅仅要往这个类里面传入特定的參数，既能够实现下来菜单，并且还能够实现菜单选择的回调。既能够反复使用，有简单便捷
首先，查看界面效果图
界面倒是比較简单，主要列下功能：
- 这个是靠一个帮助类实现的。下次想在自己的项目中实现该功能，一句引用代码，传入特定的參数既能够实现该功能
- 菜单弹出的时候。背景变灰色。菜单收回，背景回复白色
- 自己主动给选定的选项加入背景色，假设下次选择的其它选项，背景色自己主动切换
- 回调菜单的选择项
public class MenuHelper {
private PopupWindow popupWindow;
private ListView listView;
private List<String> data;
private Context mContext;
private View topView;
private ListAdapter adapter;
private int i = 0;
private FrameLayout container;
public MenuHelper(Context context, View topView, final OnMenuClick clickListener, List<String> data, FrameLayout containerView) {
mContext = context;
this.topView = topView;
this.data = data;
this.container = containerView;
container.getForeground().setAlpha(0);
topView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
showMenu();
}
});
initListView(clickListener);
initPopupWindow();
}
private void initListView(final OnMenuClick clickListener) {
listView = new ListView(mContext);
listView.setDivider(null);
listView.setDividerHeight(0);
listView.setBackgroundColor(Color.WHITE);
adapter = new ListAdapter(mContext);
listView.setAdapter(adapter);
listView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) { i = position; clickListener.onPopupMenuClick(position); popupWindow.dismiss(); } }); } private void initPopupWindow() { popupWindow = new PopupWindow(listView, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT, true); popupWindow.setOutsideTouchable(true); popupWindow.setBackgroundDrawable(new ColorDrawable(Color.WHITE)); popupWindow.setOnDismissListener(new OnDismissListener() { @Override public void onDismiss() { if (container != null) { container.getForeground().setAlpha(0); } } }); } public void showMenu() { adapter.notifyDataSetChanged(); if (popupWindow.isShowing()) { popupWindow.dismiss(); }else { popupWindow.setOutsideTouchable(true); popupWindow.setTouchable(true); popupWindow.showAsDropDown(topView, 0, 0); if (container != null) { container.getForeground().setAlpha(120); } } } private class ListAdapter extends ArrayAdapter<String> { public ListAdapter(Context context) { super(context, R.layout.item_text, data); } private Holder getHolder(final View view) { Holder holder = (Holder) view.getTag(); if (holder == null) { holder = new Holder(view); view.setTag(holder); } return holder; } @Override public View getView(final int position, View convertView, ViewGroup parent) { View rowView = convertView; if (rowView == null) { LayoutInflater inflater = LayoutInflater.from(mContext); rowView = inflater.inflate(R.layout.item_text, null); } final Holder holder = getHolder(rowView); holder.textview.setText(data.get(position)); if (position == i) { holder.textview.setBackgroundColor(mContext.getResources().getColor(R.color.item_press)); }else { holder.textview.setBackgroundColor(Color.TRANSPARENT); } return rowView; } private class Holder { public TextView textview; public Holder(View view) { textview = (TextView) view.findViewById(R.id.textView); } } }}
public interface OnMenuClick {
public void onPopupMenuClick(int position);
} 最后，是MainActivity的代码：
public class MainActivity extends Activity implements OnMenuClick{ private MenuHelper mMenuHelper; private Button button; private FrameLayout container; private List<String> menuData; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); container = (FrameLayout) findViewById(R.id.container); button = (Button) findViewById(R.id.button); menuData = new ArrayList<String>(); menuData.add("ladfj"); menuData.add("ladfj"); menuData.add("ladfj"); menuData.add("ladfj"); menuData.add("ladfj"); mMenuHelper = new MenuHelper(this, button, this, menuData, container); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { mMenuHelper.showMenu(); } }); } @Override public void onPopupMenuClick(int position) { Log.d("debug", "click position " + position); } }传送门
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