Android中的菜单

***Android中的菜单

*OptionsMenu:
onCreatOptiodMenu()方法

首先在menu文件夹下创建options_menu.xml文件：

<item 
    android:id="@+id/action_search"
    android:title="@string/action_search"/>
<item 
    android:id="@+id/action_settings"
    android:title="@string/action_settings"/>

MainActivity.java中:

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}
	//创建选项菜单--OptionsMenu
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		//获取菜单填充器对象
		MenuInflater menuinflater = getMenuInflater();
		//将menu的xml文件转换成menu对象
		menuinflater.inflate(R.menu.options_menu, menu);
		//也可以通过代码形式添加菜单项
		menu.add(Menu.NONE, Menu.NONE,Menu.NONE, "扫描");
		//返回必须是true，否则不显示menu
		return true;
	}
	//处理OptionMenu的点击事件
	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		switch (item.getItemId()) {
		case R.id.action_search:
			Toast.makeText(MainActivity.this, "搜索", Toast.LENGTH_SHORT).show();
			break;
		case R.id.action_settings:
			Toast.makeText(MainActivity.this, "设置", Toast.LENGTH_SHORT).show();
		default:
			break;
		}
		return super.onOptionsItemSelected(item);	
	}
}

*ContextMenu:
onCreatContextMenu()方法

案例效果：需长按textview控件才可显示出菜单，通过选择相应的菜单项，在title中显示控件宽高

在activity_main.xml布局文件中添加一个textView控件，values文件夹下的main.xml文件中：

<item
    android:id="@+id/action_height"
    android:title="@string/action_height"/>
<item 
    android:id="@+id/action_width"
    android:title="@string/action_width"/>

MainActivity.java中：

public class MainActivity extends Activity {
	private TextView tv;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		tv = (TextView) findViewById(R.id.tv);
		registerForContextMenu(tv);//必须注册上下文菜单-->通常上下文菜单是和ListView或者GridView这种适配器控件绑定在一起
	}
	@Override
	public void onCreateContextMenu(ContextMenu menu, View v,
			ContextMenuInfo menuInfo) {
		MenuInflater menuinflater = getMenuInflater();
		menuinflater.inflate(R.menu.main, menu);
		
		super.onCreateContextMenu(menu, v, menuInfo);
	}
	
	@Override
	public boolean onContextItemSelected(MenuItem item) {
		switch (item.getItemId()) {
		case R.id.action_height:
			setTitle("控件的高度="+tv.getHeight());
			break;
		case R.id.action_
			setTitle("控件的宽度="+tv.getWidth());
		default:
			break;
		}
		return super.onContextItemSelected(item);
	}
}

*PopupMenu:
PopupMenu popMenu = new PopupMenu(this,v)

案例显示效果：通过点击button按钮显示出菜单选项，通过选择相应的菜单选项设置textview中字体的增大和减小

activity_main.xml中布局：

<Button 
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:onClick="showPopup"
    android:textColor="#fff"
    android:background="#90C552"
    android:text="显示PopupMenu"/>

<TextView
    android:id="@+id/tv"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    android:text="@string/hello_world" />

menu文件夹下的main.xml中设置菜单选项：

<item
    android:id="@+id/action_textadd"
    android:title="@string/action_textadd"/>
<item 
    android:id="@+id/action_textsub"
    android:title="@string/action_textsub"/>

MainActivity.java文件中：

public class MainActivity extends Activity {
	private float fontSize =15.0f;
	private TextView tv;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		tv = (TextView) findViewById(R.id.tv);
	}

	public void showPopup(View view){
		PopupMenu popupmenu = new PopupMenu(this, view);//第二个参数anchor:锚点，popupmenu想要显示出来必须与一个控件绑定在一起，所以这里将其与view绑定，view也就是button
		getMenuInflater().inflate(R.menu.main, popupmenu.getMenu());
		popupmenu.show();
		//处理菜单选项点击事件
		popupmenu.setOnMenuItemClickListener(new OnMenuItemClickListener() {
			
			@Override
			public boolean onMenuItemClick(MenuItem item) {
				switch (item.getItemId()) {
				case R.id.action_textadd:
					fontSize+=5;
					break;
				case R.id.action_textsub:
					fontSize-=5;
				default:
					break;
				}
				tv.setTextSize(fontSize);
				return false;
			}
		});
	}
}