Service详解

来源：互联网发布：node strict 编辑：程序博客网时间：2024/05/18 01:19

1.简介

Service运行在后台不需要依赖UI，但是依然在主线程中。

2.使用注意

2.1 startService()

startService, Service类执行方法： onCreate(),onStartCommand().

再次调用startService，只会执行onStartCommand(). 因为onCreate()只会在Service创建的时候执行一次。每次调用 startService，都会执行onStartCommand().

stopService, Service类执行方法：onDestroy()。

我们应该始终记得在Service的onDestroy()方法里去清理掉那些不再使用的资源，防止在Service被销毁后还会有一些不再使用的对象仍占用着内存。

2.2 bindService()

bindService， Service类执行方法： onCreate(),onStartCommand().

unbindService, Service类执行方法：onDestroy().此时调用stopService()不起作用

对于startService开启的服务，调用unbindService()会让程序崩溃。

unbindService()后，再次调用unbindService()，程序会崩溃。

3.代码示例

- 模拟bindService新开线程，做一个耗时任务，发送通知给Activity，并且更新UI。

Activity类

public class ServiceActivity extends Activity implements View.OnClickListener{    private Button mBtnStopS;    private Button mBtnStartS;     private Button mBtnBindS;    private Button mBtnUnBindS;    private TextView mTvShowTest;    private TestService.MyBinderTest mBinderTest;    private ServiceConnection mConnection=new ServiceConnection() {        @Override        public void onServiceConnected(ComponentName name, IBinder service) {           mBinderTest= (TestService.MyBinderTest)service;            mBinderTest.startDownload();        }        @Override        public void onServiceDisconnected(ComponentName name) {        }    };    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_service);        initView();        registerBroadcast();    }    private void registerBroadcast() {        IntentFilter filter=new IntentFilter("com.exa.test");        registerReceiver(mReceiver,filter);    }    private void initView() {        mBtnStartS = (Button) findViewById(R.id.btn_start_service);        mBtnStopS = (Button) findViewById(R.id.btn_stop_service);        mBtnBindS = (Button) findViewById(R.id.btn_bind_service);        mBtnUnBindS = (Button) findViewById(R.id.btn_unbind_service);        mTvShowTest = (TextView) findViewById(R.id.tv_show_test);        mBtnStartS.setOnClickListener(this);        mBtnStopS.setOnClickListener(this);        mBtnBindS.setOnClickListener(this);        mBtnUnBindS.setOnClickListener(this);    }    @Override    public void onClick(View v) {        Intent intent=new Intent(ServiceActivity.this,TestService.class);        switch (v.getId()){            case R.id.btn_start_service:                startService(intent);                break;            case R.id.btn_stop_service:                stopService(intent);                break;            case R.id.btn_bind_service:                bindService(intent,mConnection, Context.BIND_AUTO_CREATE);                break;            case R.id.btn_unbind_service:                unbindService(mConnection);                break;        }    }   private BroadcastReceiver mReceiver=new BroadcastReceiver() {       @Override       public void onReceive(Context context, Intent intent) {           Log.i("TestService","ok:"+intent.getStringExtra("msg"));           mTvShowTest.setText(intent.getStringExtra("msg")+"");       }   };    @Override    protected void onStop() {        super.onStop();    }    @Override    protected void onDestroy() {        super.onDestroy();        unregisterReceiver(mReceiver);        unbindService(mConnection);    }}

Service类

public class TestService extends Service {    private static final String TAG = TestService.class.getSimpleName();    private MyBinderTest mBinderTest=new MyBinderTest();   class MyBinderTest extends Binder{        public void startDownload(){            Log.i(TAG,"startDownload");            new Thread(new Runnable() {                @Override                public void run() {                    Log.i(TAG,"run");                    Intent intent=new Intent();                    intent.setAction("com.exa.test");                    intent.putExtra("msg","来自TestService的消息");                    sendBroadcast(intent);                }            }).start();        }    }    @Nullable    @Override    public IBinder onBind(Intent intent) {        return mBinderTest;    }    @Override    public void onCreate() {        super.onCreate();        Log.i(TAG,"onCreate");    }    @Override    public int onStartCommand(Intent intent, int flags, int startId) {        Log.i(TAG,"onStartCommand");        return super.onStartCommand(intent, flags, startId);    }    @Override    public void onDestroy() {        super.onDestroy();        Log.i(TAG,"onDestroy");    }}

0 0