Android ContextMenu的使用

ContextMenu介紹：

假設一個View注冊了上下文菜單。那么當長按該View時便會彈出一個浮動菜單，來供選擇下一步操作。

實現這個功能須要調用setOnCreateContextMenuListener來注冊一個監聽器。那么它和注冊長按監聽器setOnLongClickListener有什么差別呢？以下會在代碼中加以測試，通過加入打印發現，用戶對某個View長按之后。首先觸發的是onLongClick函數，運行onLongClick操作，然后依據onLongClick的返回值推斷是不是運行OnCreateContextMenuListener函數。假設onLongClick返回false。則會繼續運行OnCreateContextMenuListener函數，假設返回true。忽略OnCreateContextMenuListener函數。

代碼例如以下：

public class MainActivity extends ActionBarActivity {

	ImageView mImageView ;
	MyContextMenuClickListener mContextListener;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.fragment_main);

		mImageView = (ImageView) findViewById(R.id.image);
		mContextListener = new MyContextMenuClickListener();
		mImageView.setOnCreateContextMenuListener(mContextListener);
		
		//test
		mImageView.setOnLongClickListener(new OnLongClickListener() {
			
			@Override
			public boolean onLongClick(View arg0) {
				// TODO Auto-generated method stub
				Log.d("Test", "onLongClick");
				return false;
			}
		});
	}

	private class MyContextMenuClickListener implements OnCreateContextMenuListener , OnMenuItemClickListener{

		@Override
		public boolean onMenuItemClick(MenuItem item) {
			// TODO Auto-generated method stub
			switch(item.getItemId()){
			case R.id.open:
				Log.d("Test", "click open");
				break;
			case R.id.delete:
				Log.d("Test", "click delete");
				break;
			case R.id.remove:
				Log.d("Test", "click remove");
				break;
			default:
					break;
			}
			return true;
		}

		@Override
		public void onCreateContextMenu(ContextMenu menu, View v,
				ContextMenuInfo menuInfo) {
			// TODO Auto-generated method stub
			Log.d("Test", "onCreateContextMenu");
			
			MenuInflater inflater = getMenuInflater();
			inflater.inflate(R.menu.context_menu, menu);
			LayoutInflater layoutInflater = getLayoutInflater();
			View view = (View) layoutInflater.inflate(
					R.layout.menu_header, null);
			menu.setHeaderView(view);
			
			MenuItem open = menu.findItem(R.id.open);
			open.setOnMenuItemClickListener(mContextListener);
			MenuItem delete = menu.findItem(R.id.delete);
			delete.setOnMenuItemClickListener(mContextListener);
			MenuItem remove = menu.findItem(R.id.remove);
			remove.setOnMenuItemClickListener(mContextListener);
		}
		
	}

}

context_menu.xml

<?xml version="1.0" encoding="UTF-8"?
>
    <menu xmlns:android="http://schemas.android.com/apk/res/android">
	    <group android:id="@+id/CONTEXT_MENU">
	    <item android:id="@+id/delete"
	        android:title="delete"/>
	    
	    <item android:id="@+id/open"
	        android:title="open"/>   
	    
	    <item android:id="@+id/remove"
	        android:title="remove"/>   
    </group>
    </menu>

menu_header.xml

<?
xml version="1.0" encoding="UTF-8"?
>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"
    >
    <TextView 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="This is a Test"
        />
    
</LinearLayout>

假設須要自己關閉ContextMenu彈框。能夠調用：

getActivity().closeContextMenu();