Service学习总结

下面是平时学习中对Service的一些总结

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Messenger使用代码：

1.先创建一个远程服务

public class MessengerService extends Service {
    private static final int MSG_SUM = 0x110;
    public MessengerService() {
    }

    Messenger messenger = new Messenger(new Handler(){
        @Override
        public void handleMessage(Message msgfromclient) {
            super.handleMessage(msgfromclient);
            //根据客户端发过来的消息创建一个message对象
            Message msgtoclient = Message.obtain(msgfromclient);
            switch (msgfromclient.what){
                case MSG_SUM:
                    msgtoclient.what = MSG_SUM;
                    try {
                        Thread.sleep(2000);
                        msgtoclient.arg2 = msgfromclient.arg1 + msgfromclient.arg2;
                        //向客户端发送消息，replyto方法获得一个messenger对象
                        msgfromclient.replyTo.send(msgtoclient);
                    }catch (RemoteException e) {
                            e.printStackTrace();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    break;
            }
        }
    });
    @Override
    public IBinder onBind(Intent intent) {
        //获得binder对象
        return messenger.getBinder();
    }
}

同时要在清单文件注册，注意加上动作

<service
            android:name=".MessengerService"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.lxn.add"/>
            </intent-filter>
        </service>

然后我们创建客户端，

private static final String TAG = "MainActivity";
    private static final int MSG_SUM = 0x110;
    boolean isBound = false;
    private Button mBtnAdd;
    private LinearLayout mLyContainer;
    //显示连接状态
    private TextView mTvState;
    private int mA;
    private Messenger mService;
    private Messenger messenger = new Messenger(new Handler(){
        @Override
        public void handleMessage(Message msgFromServer) {
            super.handleMessage(msgFromServer);
            switch (msgFromServer.what){
                case MSG_SUM:
                    TextView tv = (TextView) mLyContainer.findViewById(msgFromServer.arg1);
                    tv.setText(tv.getText() + "=>" + msgFromServer.arg2);
                    break;
            }
        }
    });
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTvState = (TextView) findViewById(R.id.id_tv_callback);
        mBtnAdd = (Button) findViewById(R.id.id_btn_add);
        mLyContainer = (LinearLayout) findViewById(R.id.id_ll_container);
        invokeBindService();
        mBtnAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int a = mA++;
                int b = (int) (Math.random()*100);
                TextView textview = new TextView(MainActivity.this);
                textview.setText(a + " + " + b + " = caculating ...");
                textview.setId(a);
                mLyContainer.addView(textview);

                Message msgfromclient = Message.obtain(null, MSG_SUM, a, b);
                msgfromclient.replyTo = messenger;
                if(isBound){
                    try {
                        mService.send(msgfromclient);//向服务器发消息
                    } catch (RemoteException e) {
                        e.printStackTrace();
                    }
                }
            }
        });
    }

    private void invokeBindService() {
        Intent intent = new Intent();
        //绑定服务，远程服务必须指定action
        intent.setAction("com.lxn.add");
        bindService(intent,conn,BIND_AUTO_CREATE);
    }

    ServiceConnection conn = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            mService = new Messenger(service);
            isBound = true;
            mTvState.setText("connected");
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            isBound  = false;
            mService = null;
            mTvState.setText("disconnected");
        }
    };

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if(isBound){
            unbindService(conn);
            isBound = false;
        }
    }
}