安卓入门-UI Components 之Menu (菜单)

安卓入门

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UI Components 之Menu (菜单)

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1.UI Components 是什么？
1)UI 对象（负责呈现view）
2)它不是view.它通过view呈现数据，实现与用户交互。



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2.Menu 是什么？
1)Android 中的一种菜单对象类型。
2)Android 中的一种呈现view的对象。


3.Menu 对象应用类型？


1)选项菜单（Option Menu）
2)上下文菜单(Context Menu)
3)弹出式菜单(PopuMenu)
4)子菜单(SubMenu 每种菜单都有子菜单)


4.选项菜单构建及应用？
1)构建选项菜单(重写activity中的onCreateOptionMenu)
2)处理选项菜单监听(重写activity中的onOptionItemSelected)

5.上下文菜单的创建及应用（基于view的长按事件）
0)在view上注册上下文菜单(registerForContextMenu)
1)构建上下文菜单(重写activity中的onCreateContextMenu)
2)处理上下文菜单监听(重写activity中的onContextItemSelected)


案例:listview 长按时弹出上下文菜单(删除，分享)

public class MainActivity extends Activity {

	private List<String> data=new ArrayList<String>();
	public MainActivity() {
		data.add("A");
		data.add("B");
		data.add("C");
	}
	ArrayAdapter<String> adapter;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	    ListView lsv=(ListView) findViewById(R.id.lsvId);
	    adapter=new ArrayAdapter<String>(this, 
	    	    android.R.layout.simple_list_item_1,
	    	    data);
	    lsv.setAdapter(adapter);
	    
	    //注册上下文菜单
	    registerForContextMenu(lsv);
	}
	/**长按listview的item时会执行此方法*/
	@Override
	public void onCreateContextMenu(
			ContextMenu menu, View v,
			ContextMenuInfo menuInfo) {
		//getMenuInflater().inflate(menuRes, menu)
		
		//基于java方式创建菜单项
		menu.add(0, 101,//itemId
				201,//orderId (序号)
				"删除"//title
				);
		menu.add(0, 102,//itemId
				202,//orderId
				"分享"//title
				);
	}
	/**当我们点击上下文菜单中的选项时自动执行此方法*/
	@Override
	public boolean onContextItemSelected(MenuItem item) {
		
	
		ContextMenuInfo c=item.getMenuInfo();
		
		Log.i("TAG", "c="+c);
		AdapterContextMenuInfo acm=
		(AdapterContextMenuInfo)c;
		//获得长按的位置
		int pos=acm.position;
		
		if(item.getItemId()==101){
		//删除数据
		 data.remove(pos);
		 //刷新listview
		 adapter.notifyDataSetChanged();
		}else if(item.getItemId()==102){
		 //分享的action: ACTION_SEND
		 Intent target=new Intent(Intent.ACTION_SEND);
		 //设置税局类型
		 target.setType("text/*");
		 //设置要分享的数据
		 target.putExtra(Intent.EXTRA_TEXT, data.get(pos));
		 //创建分享目标
		 Intent intent=
		 Intent.createChooser(target, "请选择");
		 //启动activity
		 startActivity(intent);	
		}return true;
	}


}

6.弹出式菜单(基于view的点击事件):了解


1)创建菜单(PopuMenu)及菜单项
2)显示菜单(show)
3)添加监听(setOnMenuItemClickListener)

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}

	public void onClick(final View v){
		//构建菜单对象
		PopupMenu pm=
		new PopupMenu(this, v);
		//初始化菜单中的item
		pm.getMenuInflater().
		inflate(R.menu.pop,
		pm.getMenu());
		//pm.getMenu().add(groupId, itemId, order, title)
		//添加监听
		pm.setOnMenuItemClickListener(
			new OnMenuItemClickListener() {
			@Override
			public boolean onMenuItemClick(MenuItem item) {
				((Button)v).setText(item.getTitle());
				return false;
			}
		});
		//显示菜单
		pm.show(); 
	}

}

8.子菜单(菜单项中还可以添加菜单)


案例：选项菜单中添加子菜单(xml,java)

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}

	private Menu menu;
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		this.menu=menu;
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		
		//通过java方式添加子菜单
		SubMenu sm=
		menu.addSubMenu(0,1000,
		101, "item02");
		
		MenuItem item=menu.findItem(1000);
		item.setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS);
	    //添加菜单项
		sm.add(0, 2000, 200, "item0002");
		return true;
	}
	public void onClick(View v){
		menu.setGroupVisible(R.id.group01, true);
	}

}

menu-xml文件如下：

<?xml version="1.0"?>

-<menu xmlns:android="http://schemas.android.com/apk/res/android">


-<group android:visible="false" android:id="@+id/group01">


-<item android:title="item01" android:id="@+id/item01" android:showAsAction="ifRoom" android:orderInCategory="100">


-<menu>

<item android:title="item001" android:id="@+id/item001" android:showAsAction="never" android:orderInCategory="300"/>

<item android:title="item002" android:id="@+id/item002" android:showAsAction="never" android:orderInCategory="301"/>

</menu>

</item>

</group>

</menu>

7.菜单的分组（可以同时显示或隐藏多个菜单项）


1)创建(xml:group)
2)调用menu对象的相关方法操作分组(例如显示或隐藏setGroupVisible)


9.侧滑菜单(菜单扩展)
1)DrawerLayout 布局（根元素必须是drawerlayout）
2)DrawerLayout 对象 (findViewByid)
a)初始化listview对象(侧滑item对象)
b)初始化framelayout对象

3)DrawerLayout 添加监听对象

public class MainActivity extends Activity implements OnItemClickListener {

	private List<Item> list=new ArrayList<Item>();
	public MainActivity() {
		list.add(new Item(android.R.drawable.ic_menu_save,"我的收藏"));
		list.add(new Item(android.R.drawable.ic_menu_camera,"我的设置"));
		list.add(new Item(android.R.drawable.ic_menu_delete,"退出"));
	}
	private DrawerLayout drawerLayout;
	private TextView contentTv;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		setDrawerLayout();
		setDrawerListView();
		setContent();
	}

	private void setContent() {
		contentTv=(TextView) findViewById(R.id.textId);
	}

	private void setDrawerListView() {
		ListView lsv=(ListView) findViewById(R.id.lsvId);
	    lsv.setAdapter(new ArrayAdapter<Item>(this,
	    android.R.layout.simple_list_item_1,list){
	    	@Override
	    	public View getView(int position, View convertView, ViewGroup parent) {
	    		TextView v=(TextView)View.inflate(getContext(),  android.R.layout.simple_list_item_1, null);
	    		Item item=getItem(position);
	    		//获得图片资源的drawable对象
	    		Drawable left=getResources()
	    		.getDrawable(item.getLogo());
	    		//设定对象的边界
	    		left.setBounds(0, 0,50, 50);
	    		//将left对象绘制到v的左边
	    		v.setCompoundDrawables(left,
	    		null, null, null);
	    		
	    		v.setText(item.getName());
	    		return v;
	    	}
	    });
	    lsv.setOnItemClickListener(this);
	}
	private ActionBarDrawerToggle drawerToggle;
	private void setDrawerLayout() {
		 getActionBar().setDisplayHomeAsUpEnabled(true);//显示图标
		drawerLayout=(DrawerLayout) findViewById(R.id.drawerLayoutId);
	    drawerToggle=new ActionBarDrawerToggle(this,
	    drawerLayout,
	    R.drawable.top_menu_on, R.string.open_drawer,R.string.close_drawer){
	    	@Override
	    	public void onDrawerOpened(View drawerView) {
	    		super.onDrawerOpened(drawerView);
	    		setTitle("Open");
	    	}
	    	@Override
	    	public void onDrawerClosed(View drawerView) {
	    		super.onDrawerClosed(drawerView);
	    		setTitle("Close");
	    	}
	    };
		drawerLayout.setDrawerListener(drawerToggle);
	}
	
	/**选项菜单创建之前执行，在此方法中同步drawerLayout状态*/
	@Override
	protected void onPostCreate(Bundle savedInstanceState) {
		super.onPostCreate(savedInstanceState);
		drawerToggle.syncState();
	}
	
	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		//打开或收起drawerlayout对象
		if(drawerToggle.onOptionsItemSelected(item)){
			return true;
		}
		return true;
	}
	@Override
	public void onItemClick(AdapterView<?> parent, View view, int position,long id) {
		Item item=(Item)parent.getItemAtPosition(position);
		contentTv.setText(item.getName());
		drawerLayout.closeDrawer(parent);
	}
	class Item{
		private int logo;
		private String name;
		public Item(int logo,String name) {
			this.logo=logo;
			this.name=name;
		}
		public int getLogo() {
			return logo;
		}
		public String getName() {
			return name;
		}
	}
}

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