android教程之使用popupwindow创建菜单示例

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
    }
}

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>