2023学年完整公开课版长按事件

《通信业务开发》课程长按事件长按LongClick事件PART18-7事件特性监听接口实例演示事件特性示例控件长按超过2s触发的事件，常用于设置桌面类似应用接口：View.OnLongClickListener.

onLongClick()实现步骤：获取监听对象：创建监听器类,实现View.OnLongClickListener注册监听器：

setOnLongClickListener()规则监听接口publicstaticinterfaceView.OnLongClickListener{ publicbooleanonLongClick(Viewv);}voidsetOnLongClickListener(View.OnLongClickListener

l)实例演示<LinearLayout

xmlns:android="/apk/res/android"

android:layout_width="match_parent"

android:layout_height="match_parent"

>

<ImageView

android:id="@+id/img"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignParentTop="true"

android:layout_centerHorizontal="true"

android:layout_marginTop="18dp"

android:src="@drawable/a"

tools:ignore="ContentDescription"

/>

</LinearLayout>

XML布局实例演示public

class

MainActivity

extends

Activity

{

@Overridepublic

voidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState); setContentView(R.layout.main);

ImageViewimg=(ImageView)findViewById(R.id.img); img.setOnLongClickListener(newOnLongClickListener(){

@Override

public

boolean

onLongClick(Viewview){

try{clearWallpaper();setWallpaper(img.getResources().openRawResource(R.drawable.mldn_bg)); }catch(Exceptione){ }

return

true;} });}}

选项改变监听实现No.方法类型描述1publicvoidclearWallpaper()普通清除已有的手机屏幕2publicvoidsetWallpaper(Bitmapbitmap)普通通过Bitmap设置手机屏幕3publicvoidsetWallpaper(InputStreamdata)普通通过输入流设置手机屏幕4publicDrawablegetWallpaper()普通