安卓学习笔记：使用PopupWindow创建简单菜单

PopupWindow是一个弹出式窗口，它可以展示任意View。他会浮在当前窗口的上方展示。

下面看代码：

public class MyActivity extends Activity

{

    private PopupWindow menu;

    private LayoutInflater inflater;

    private View layout;

    @Override

    public void onCreate(Bundle savedInstanceState)

    {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        //实例化PopupWindow创建菜单

        initMenu();

    }

    //判断按键 菜单的显示与隐藏

    @Override

    public boolean onKeyDown(int keyCode, KeyEvent event) {

        if(!menu.isShowing()&&keyCode == KeyEvent.KEYCODE_MENU){

           show();

        }else{

            menu.dismiss();

        }

        if(keyCode == KeyEvent.KEYCODE_BACK&&menu.isShowing()){

            menu.dismiss();

        }

        return true;

    }

    //实例化PopupWindow创建菜单

    private void initMenu(){

            //获取LayoutInflater实例

            inflater  = (LayoutInflater) this.getSystemService(LAYOUT_INFLATER_SERVICE);

            //获取弹出菜单的布局

            layout = inflater.inflate(R.layout.menu,null);

            //设置popupWindow的布局

            menu = new PopupWindow(layout, WindowManager.LayoutParams.WRAP_CONTENT,WindowManager.LayoutParams.WRAP_CONTENT);

    }

    //显示菜单

    private void show(){

           //设置位置

            menu.showAtLocation(this.findViewById(R.id.main), Gravity.BOTTOM|Gravity.CENTER_HORIZONTAL,0,0); //设置在屏幕中的显示位置

    }

}

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菜单的布局文件：

<?xml version="1.0" encoding="utf-8"?>

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

              android:layout_width="fill_parent"

              android:layout_height="fill_parent"

              android:orientation="horizontal"

        >

    <ImageView

        android:id="@+id/icon_1"

        android:background="@drawable/icon_1"

        android:layout_width="40dp"

        android:layout_height="40dp"/>

    <ImageView

        android:id="@+id/icon_2"

        android:background="@drawable/icon_2"

        android:layout_width="40dp"

        android:layout_height="40dp"/>

    <ImageView

        android:id="@+id/icon_3"

        android:background="@drawable/icon3"

        android:layout_width="40dp"

        android:layout_height="40dp"/>

    <ImageView

        android:id="@+id/icon_4"

        android:background="@drawable/icon4"

        android:layout_width="40dp"

        android:layout_height="40dp"/>

</LinearLayout>

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