Android四大组件全面解析，夯实基础。（中）

public class ServiceDemo extends Service {
    private MyBinder binder=new MyBinder();
    @Override
    public void onCreate() {
        super.onCreate();
        Log.e("demo","onCreate创建");
    }
    @Override
    public boolean onUnbind(Intent intent) {
        Log.e("demo","解绑");
        return super.onUnbind(intent);
    }
    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.e("demo","销毁");
    }
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.e("demo","onStartCommand服务启动");
        return super.onStartCommand(intent, flags, startId);
    }
    class MyBinder extends Binder {
        private CountDownTimer count;
        public void start(){
            count = new CountDownTimer(Integer.MAX_VALUE,1000) {
                @Override
                public void onTick(long millisUntilFinished) {
                    Toast.makeText(ServiceDemo.this, "启动啦", Toast.LENGTH_SHORT).show();
                }
                @Override
                public void onFinish() {
                }
            }.start();
        }
        public void onstop(){
            if (count != null) {
                count.cancel();
                count=null;
            }
        }
    }
    @Override
    public IBinder onBind(Intent intent) {
        Log.e("Demo","bind");
        return binder;
    }
}

public class MyServerConnection implements ServiceConnection {
    private ServiceDemo.MyBinder myBinder;
    /**
     * 第二个参数是Server中的onBind方法返回的。
     *
     * @param name
     * @param service
     */
    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
        Log.e("demo","开始");
        myBinder = (ServiceDemo.MyBinder) service;
        myBinder.start();
    }
    @Override
    public void onServiceDisconnected(ComponentName name) {
        myBinder.onstop();
    }
}

public class Main2Activity extends AppCompatActivity {
    MyServerConnection myServerConnection=new MyServerConnection();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        findViewById(R.id.btn_start).setOnClickListener(v -> {
            Log.e("demo","startService启动服务");
            Intent intent=new Intent(this,ServiceDemo.class);
            bindService(intent,myServerConnection,BIND_AUTO_CREATE);
        });
        findViewById(R.id.btn_stop).setOnClickListener(v -> {
            Log.e("demo","stopService服务关闭");
           unbindService(myServerConnection);
        });
    }
}

Context.sendBroadcast()
发送的是普通广播，所有订阅者都有机会获得并进行处理。

Context.sendOrderedBroadcast()
发送的是有序广播，系统会根据接收者声明的优先级别按顺序逐个执行接收者，前面的接收者有权终止广播(BroadcastReceiver.abortBroadcast())，如果广播被前面的接收者终止，后面的接收者就再也无法获取到广播。对于有序广播，前面的接收者可以将处理结果通过setResultExtras(Bundle)方法存放进结果对象，然后传给下一个接收者，通过代码：Bundle bundle =getResultExtras(true))可以获取上一个接收者存入在结果对象中的数据。
系统收到短信，发出的广播属于有序广播。如果想阻止用户收到短信，可以通过设置优先级，让你们自定义的接收者先获取到广播，然后终止广播，这样用户就接收不到短信了。

public class MyReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.e("demo", "接收到一条消息");
    }
}

public class MainActivity extends AppCompatActivity {
  @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main4);
        findViewById(R.id.btn_send_Nor).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent=new Intent("xxx");
                sendBroadcast(intent);
            }
        });
    }
}

//xml
<receiver
    android:name=".BroadcstReceiver.MyReceiver"
    android:enabled="true"
    android:exported="true">
    <intent-filter>
        <action android:name="xxx"/>
    </intent-filter>
</receiver>