02Handler消息传递机制.ppt

Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,*,,,,,Click to edit Master title style,,,,,,,,,,,,,,,,,Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,Click to edit Master title style,,,,*,,,,,,Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,Click to edit Master title style,,Logo,*,,,,,,Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,Click to edit Master title style,,Logo,*,,,,,,Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,Click to edit Master title style,,Logo,*,,,,,,Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,Click to edit Master title style,,Logo,*,,,,,,Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,Click to edit Master title style,,Logo,*,,,,,,Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,Click to edit Master title style,,Logo,*,,,,,,Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,Click to edit Master title style,,Logo,*,,,,,,Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,Click to edit Master title style,,Logo,*,,,,,,Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,Click to edit Master title style,,Logo,*,,,,,,Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,Click to edit Master title style,,Logo,*,,,,,,Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,Click to edit Master title style,,Logo,*,,,,,,Click to edit Master text styles,,Second level,,Third level,,Fourth level,,Fifth level,,Click to edit Master title style,,Logo,*,Handler,消息传递机制,本讲大纲,：,1,、循环者,Looper,简介,2,、消息处理类,Handler,简介,支持网站：,www.,mrbccd,.com,3,、消息类,Message,简介,4,、范例,1,：开启新线程获取网络图片并显示到,ImageView,中,5,、范例,2,：开启新线程实现电子广告牌,循环者,Looper,简介,Looper,对象用来为一个线程开启一个消息循环，用来操作,MessageQueue,。

Looper,类提供的常用方法如下表所示方法,描述,prepare(),用于初始化,Looper,loop(),调用,loop(),方法后，,Looper,线程就开始真正工作了，它会从消息队列里获取消息和处理消息,myLooper(),可以获取当前线程的,Looper,对象,getThread(),用于获取,Looper,对象所属的线程,quit(),用于结束,Looper,循环,,消息处理类,Handler,简介,,消息,处理类（,Handler,）允许发送和处理,Message,或,RannableRunnable,对象到其所程的,MessageQueue,中Handler,类提供的常用的发送和处理消息的方法,如下表所,示方法,描述,handleMessage(Message msg),处理消息的方法通常重写该方法来处理消息，在发送消息时，该方法会自动回调,post(Runnable r),立即发送,Runnable,对象，该,Runnable,对象最后将被封装成,Message,对象,postAtTime(Runnable r, long uptimeMillis),定时发送,Runnable,对象，该,Runnable,对象最后将被封装成,Message,对象,postDelayed(Runnable r, long delayMillis),延迟多少毫秒发送,Runnable,对象，该,Runnable,对象最后将被封装成,Message,对象,sendEmptyMessage(int what),发送空消息,sendMessage(Message msg),立即发送消息,sendMessageAtTime(Message msg, long uptimeMillis),定时发送消息,sendMessageDelayed(Message msg, long delayMillis),延迟多少毫秒发送消息,消息类,Message,简介,,属性,类型,描述,arg1,int,用来存放整型数据,arg2,int,用来存放整型数据,obj,Object,用来存放发送给接收器的,Object,类型的任意对象,replyTo,Messenger,用来指定此,Message,发送到何处的可选,Messager,对象,what,int,用于指定用户自定义的消息代码，这样接收者可以了解这个消息的信息,范例,1,：开启新线程获取网络图片并显示到,ImageView,中,在,Eclipse,中创建,Android,项目，开启新线程获取网络图片并显示到,ImageView,中。

范例,2,：开启新线程实现电子广告牌,在,Eclipse,中创建,Android,项目，开启新线程实现电子广告牌Thank you,还有什么疑问可以到,www.,mrbccd,.com,提出,,也可以以发送邮件到,mingrisoft,@,mingrisoft,.com,,。