【Android】菜单功能的实现：使用XML

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

<item
android:id="@+id/action_settings"
android:icon="@drawable/ic_launcher"
android:orderInCategory="100"
android:showAsAction="ifRoom|withText"
android:title="@string/action_settings">
<menu>
<item
android:id="@+id/create_new"
android:title="新建文件">
</item>
<item
android:id="@+id/open"
android:title="打开文件">
</item>
</menu>
</item>
<item
android:id="@+id/sys"
android:icon="@drawable/ic_launcher"
android:orderInCategory="101"
android:showAsAction="never"
android:title="用户菜单">
<menu>
<group android:id="@+id/group1" >
<item
android:id="@+id/load"
android:title="加载文件">
</item>
</group>
<group android:id="@+id/group2" >
<item
android:id="@+id/save"
android:title="保存文件">
</item>
</group>
</menu>
</item>

</menu>

@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;
}

@Override
public boolean onMenuItemSelected(int featureId, MenuItem item) {
// TODO Auto-generated method stub
switch (item.getItemId()) {
case R.id.create_new:
Intent intent = new Intent(MainActivity.this, SystemMunu.class);
item.setIntent(intent);
break;
case R.id.open:
Toast.makeText(MainActivity.this, "打开菜单", Toast.LENGTH_SHORT).show();
break;
case R.id.load:
Toast.makeText(MainActivity.this, "加载菜单", Toast.LENGTH_SHORT).show();
break;
case R.id.save:
Toast.makeText(MainActivity.this, "保存菜单", Toast.LENGTH_SHORT).show();
break;

default:
break;
}

return super.onMenuItemSelected(featureId, item);
}

android:showAsAction="ifRoom|withText"