Android PopupMenu弹出菜单的实现

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"   xmlns:tools="http://schemas.android.com/tools"   android:layout_width="match_parent"   android:layout_height="match_parent"   android:paddingBottom="@dimen/activity_vertical_margin"   android:paddingLeft="@dimen/activity_horizontal_margin"   android:paddingRight="@dimen/activity_horizontal_margin"   android:paddingTop="@dimen/activity_vertical_margin"   tools:context=".MainActivity" >    <Button     android:id="@+id/button1"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_alignParentLeft="true"     android:layout_alignParentTop="true"     android:layout_marginLeft="96dp"     android:layout_marginTop="111dp"     android:onClick="showPopup"     android:text="弹出菜单" />  </RelativeLayout> 

<menu xmlns:android="http://schemas.android.com/apk/res/android" >    <item     android:id="@+id/open"     android:orderInCategory="100"     android:showAsAction="never"     android:title="@string/open"/>   <item     android:id="@+id/close"     android:orderInCategory="100"     android:showAsAction="never"     android:title="@string/close"/>  </menu> 

package com.example.menu_popupmenu;  import android.os.Bundle; import android.app.Activity; import android.view.Menu; import android.view.View; import android.widget.Button; import android.widget.PopupMenu;  public class MainActivity extends Activity {    private Button button;    @Override   protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);   }    public void showPopup(View view) {     PopupMenu popupMenu = new PopupMenu(MainActivity.this, view);     popupMenu.getMenuInflater().inflate(R.menu.main, popupMenu.getMenu());     popupMenu.show();   }    @Override   public boolean onCreateOptionsMenu(Menu menu) {     // Inflate the menu; this adds items to the action bar if it is present.     getMenuInflater().inflate(R.menu.main, menu);     return true;   }  }