• 浅谈Service


    一。生命周期:

    startService()方式启动,Service是通过接受Intent并且会经历onCreate()和onStart()。当用户在发出意图使之销毁时会经历onDestroy();( onCreate-->onStart-->onDestory )

    bindService()方式启动,与Activity绑定的时候,会经历onCreate()和onBind(),而当Activity被销毁的时候,Service会先调用onUnbind()然后是onDestroy()。( onCreate-->onBind -->onUnbind-->onDestory)

    二。控制方式:

    StartService的控制方式需要使用固定的方法,对Service进行单一的操作。

    而BindService由于与Activity绑定,不用考虑其生命周期问题,并且从发送Intent的被动操作,变为可以主动对Service对象进行操作,我们甚至可以建立一个Handler类,对Service进行相关的操作。大大加强了Service的灵活性、可操作性。

    总结:对于简单的应用startService()启动方式能带来更少的代码,简单的操作。对于复杂的应用bindService()方式,虽然带来的更多的编码,但同时也带来了更好的可操作性,使其使用起来更像Activity。

    注意:

    Service的生命周期方法比Activity少一些,只有onCreate, onStart, onDestroy 我们有两种方式启动一个Service,他们对Service生命周期的影响是不一样的。

    1 通过startService 
    Service会经历 onCreate --> onStart 

    stopService的时候直接onDestroy,如果是 调用者 直接退出而没有调用stopService的话,Service会一直在后台运行,下次调用者再起来仍然可以stopService。

    2 通过bindService 
    Service只会运行onCreate, 这个时候 调用者和Service绑定在一起,调用者退出了,Srevice就会调用onUnbind-->onDestroyed,所谓绑定在一起就共存亡了。 

    注意:Service的onCreate的方法只会被调用一次,
    就是你无论多少次的startService又 bindService,Service只被创建一次。
    如果先是bind了,那么start的时候就直接运行Service的onStart方法,
    如果先是start,那么bind的时候就直接运行onBind方法。如果你先bind上了,就stop不掉了,
    只能先UnbindService, 再StopService,所以是先start还是先bind行为是有区别的。 

    代码:

    一。startService -->service内容:

    public class MyService extends Service{
    
        private static final String TAG = "MyService";  
        MediaPlayer player;
        
        @Override
        public IBinder onBind(Intent intent) {
            return null;
        }
    
        @Override  
        //服务启动前进行的配置
        public void onCreate() {
            Toast.makeText(this, "My Service created", Toast.LENGTH_LONG).show();  
            Log.i(TAG, "onCreate");  
            
            //播放设置
            player = MediaPlayer.create(this, R.raw.music);//提供音乐的位置  
            player.setLooping(false);  //是否循环播放音乐
        }  
      
        @Override  
        //关闭服务
        public void onDestroy() {  
            Toast.makeText(this, "My Service Stoped", Toast.LENGTH_LONG).show();  
            Log.i(TAG, "onDestroy");  
            player.stop();  
        }  
      
        @Override  
        //启动服务
        public void onStart(Intent intent, int startid) {  
            Toast.makeText(this, "My Service Start", Toast.LENGTH_LONG).show();  
            Log.i(TAG, "onStart");  
            player.start();  
        }  
        
    }


    Activity的内容:

    public class Activityone extends Activity{
        
        private static final String TAG = "ServiceDemo"; 
        private Button mybuttonone1;
        private Button mybuttonone2;
        
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_one);
            
            mybuttonone1 = (Button)findViewById(R.id.buttonone1);
            mybuttonone2 = (Button)findViewById(R.id.buttonone2);
                    
            //service通过startservice启动服务
            //首先调用mybuttonone1的onclick方法,然后调用myservice的onclick()方法,再然后调用onstart()方法
            mybuttonone1.setOnClickListener(new OnClickListener() {
                
                @Override
                public void onClick(View v) {
                    Log.i(TAG, "onClick: starting service");
                    startService(new Intent(Activityone.this, MyService.class));
                }
            });
            
            //service通过startservice关闭服务
            //首先调用mybuttonone2的onclick方法,然后调用myservice的onstop()方法
            
            mybuttonone2.setOnClickListener(new OnClickListener() {
                
                @Override
                public void onClick(View v) {
                    Log.i(TAG, "onClick: stopping service");  
                    stopService(new Intent(Activityone.this, MyService.class));  
                }
            });
            
            mybuttonone1.setOnClickListener(new myclicklistener());
            mybuttonone2.setOnClickListener(new myclicklistener());
            
        }
        
        class myclicklistener implements OnClickListener{
            public void onClick(View src) {  
                switch (src.getId()) {  
                    case R.id.buttonone1:  
                        Log.i(TAG, "onClick: starting service");  
                        startService(new Intent(Activityone.this, MyService.class));  
                //startservice  执行的步骤:  onclick()-->onstart()
                        break;  
                    case R.id.buttonone2:  
                        Log.i(TAG, "onClick: stopping service");  
                        stopService(new Intent(Activityone.this, MyService.class));  
                //startservice  执行的步骤:  onDestroy()
                        break;  
                }  
            }  
        }
        
    }


    二。BindService -->service内容:
    public class BindService extends Service {
        
        private MyBinder myBinder = new MyBinder();
        private static final String TAG = "BindService";
        private MediaPlayer play;
        
        @Override
        public IBinder onBind(Intent intent) {
                Log.i(TAG, "BindService-->onBind()");
                
                play=MediaPlayer.create(this, R.raw.music);
                play.setLooping(false);
                
                return myBinder;
            }
        
        public class MyBinder extends Binder{
            
            public BindService getService(){
                Log.i(TAG, "BindService-->getService()");
                return BindService.this;
            }
        }
        
        public void MyMethod(){
            Log.i(TAG, "BindService-->MyMethod()");
            play.start();
        }
         
    }


    Activity的代码:
    public class Activitytwo extends Activity{
        
        private Button mybutton1;
        private Button mybutton2;
        private boolean flag;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_two);
            
            mybutton1=(Button)findViewById(R.id.buttontwo1);
            mybutton2=(Button)findViewById(R.id.buttontwo2);
            
            mybutton1.setOnClickListener(new myclicklistener());
            mybutton2.setOnClickListener(new myclicklistener());
            
        }
        
        class myclicklistener implements OnClickListener{
    
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                switch (v.getId()) {
                case R.id.buttontwo1:
                    System.out.println("打开bind1");
                    bindService();
                    break;
                    
                case R.id.buttontwo2:
                    System.out.println("关闭bind1");
                    unBind();
                    break;    
                    
                default:
                    break;
                }
            }
        }
    
        private void bindService(){
            System.out.println("打开bind2");
            Intent intent = new Intent(Activitytwo.this,BindService.class);
            bindService(intent, conn, Context.BIND_AUTO_CREATE);
        }
        
        private void unBind(){
            System.out.println("关闭bind2");
            if(flag == true){
                unbindService(conn);
                flag = false;
            }
        }
        
        private ServiceConnection conn = new ServiceConnection() {
            
            @Override
            public void onServiceDisconnected(ComponentName name) {
                System.out.println("关闭bind3");
            }
            
            @Override
            public void onServiceConnected(ComponentName name, IBinder service) {
                System.out.println("打开bind3");
                MyBinder binder = (MyBinder)service;
                BindService bindService = binder.getService();
                bindService.MyMethod();
                flag = true;
            }
        };
        
    }


    你必须非常努力,才能看起来毫不费力。。。
  • 相关阅读:
    Single Number II
    Best Time to Buy and Sell Stock
    Linked List Cycle
    Single Number
    Max Points on a Line
    Strategy
    LRU Cache
    Word Break II
    Text Justification
    Median of Two Sorted Arrays
  • 原文地址:https://www.cnblogs.com/yiweiaimeng/p/4944715.html
Copyright © 2020-2023  润新知