編輯：關於Android編程
前面已經對Service的startServer方式啟動一個服務了解過了，現在來看一下Service的另一種啟動方式→bindServer
bindServer使用場景
1、在同個app之間調用（即是同一個進程中）
2、在不同app之間調用（即是跨進程間通信）
同個app間調用（只有一次啟動該服務）
BinderActicityA
public class BinderActicityA extends Activity implements View.OnClickListener {
private Button btn1;
private Button btn2;
private Button btn3;
private Button btn4;
private BindService bindService = null;
private boolean isBound = false;
private ServiceConnection conn = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
isBound = true;
BindService.MyBinder binder = (BindService.MyBinder) service;
bindService = binder.getService();
int num = bindService.getRandomNumber();
Log.v("hjz","numA="+num);
}
//client 和service連接意外丟失時，會調用該方法
@Override
public void onServiceDisconnected(ComponentName name) {
Log.v("hjz","onServiceDisconnected A");
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_binder_main);
findLayoutView();
setLister();
initData();
}
private void findLayoutView() {
btn1 = (Button) findViewById(R.id.btn1);
btn2 = (Button) findViewById(R.id.btn2);
btn3 = (Button) findViewById(R.id.btn3);
btn4 = (Button) findViewById(R.id.btn4);
}
private void setLister() {
btn1.setOnClickListener(this);
btn2.setOnClickListener(this);
btn3.setOnClickListener(this);
btn4.setOnClickListener(this);
}
private void initData() {
}
@Override
public void onClick(View v) {
Intent intent = null;
switch (v.getId()){
case R.id.btn1:
intent = new Intent(BinderActicityA.this, BindService.class);
intent.putExtra("from", "ActivityA");
bindService(intent,conn,BIND_AUTO_CREATE);
break;
case R.id.btn2:
if (isBound){
isBound = false;
Log.v("hjz","ActicityA is unbindService");
unbindService(conn);
}
break;
case R.id.btn3:
intent = new Intent(this, BinderActivityB.class);
startActivity(intent);
break;
case R.id.btn4:
this.finish();
break;
}
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.i("hjz", "ActivityA -> onDestroy");
}
}
xml
BinderService
public class BindService extends Service {
public class MyBinder extends Binder{
public BindService getService(){
return BindService.this;
}
}
//通過binder實現了 調用者（client）與 service之間的通信
private MyBinder binder = new MyBinder();
private final Random generator = new Random();
@Override
public void onCreate() {
super.onCreate();
Log.i("hjz","BindService -> onCreate, Thread: " + Thread.currentThread().getName());
}
@Override
public IBinder onBind(Intent intent) {
Log.i("hjz", "BindService -> onBind, Thread: " + Thread.currentThread().getName());
return binder;
}
@Override
public boolean onUnbind(Intent intent) {
Log.i("hjz", "BindService -> onUnbind, from:" + intent.getStringExtra("from"));
return false;
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.i("hjz", "BindService -> onStartCommand, startId: " + startId + ", Thread: " + Thread.currentThread().getName());
return START_NOT_STICKY;
}
@Override
public void onDestroy() {
Log.i("hjz", "BindService -> onDestroy, Thread: " + Thread.currentThread().getName());
super.onDestroy();
}
//在Service中暴露出去的方法，供client調用
public int getRandomNumber(){
return generator.nextInt();
}
}
點擊BinderService綁定，再點擊BinderService解綁，最後點擊finish，打印日志
07-09 11:46:49.360 29714-29714/com.hh.servicedemo I/hjz: BindService -> onCreate, Thread: main 07-09 11:46:49.360 29714-29714/com.hh.servicedemo I/hjz: BindService -> onBind, Thread: main 07-09 11:46:49.380 29714-29714/com.hh.servicedemo V/hjz: numA=1859239539 07-09 11:46:50.650 29714-29714/com.hh.servicedemo V/hjz: ActicityA is unbindService 07-09 11:46:50.650 29714-29714/com.hh.servicedemo I/hjz: BindService -> onUnbind, from:ActivityA 07-09 11:46:50.650 29714-29714/com.hh.servicedemo I/hjz: BindService -> onDestroy, Thread: main 07-09 11:46:52.290 29714-29714/com.hh.servicedemo I/hjz: ActivityA -> onDestroy
07-09 11:48:07.260 29714-29714/com.hh.servicedemo I/hjz: BindService -> onCreate, Thread: main 07-09 11:48:07.260 29714-29714/com.hh.servicedemo I/hjz: BindService -> onBind, Thread: main 07-09 11:48:07.270 29714-29714/com.hh.servicedemo V/hjz: numA=-341510490 07-09 11:48:09.290 29714-29714/com.hh.servicedemo I/hjz: ActivityA -> onDestroy 07-09 11:48:09.310 29714-29714/com.hh.servicedemo I/hjz: BindService -> onUnbind, from:ActivityA 07-09 11:48:09.310 29714-29714/com.hh.servicedemo I/hjz: BindService -> onDestroy, Thread: main
先從BinderService來分析，從打印可以看出，先調用onCreate，接著在調用onBind方法，你會發現使用binderStart來啟動，onStartCommand這方法不調用；在Service中執行順序：
1、先得到相應的binder對象，可以在Service內部用內部類得到相應的binder，如下所示：
public class MyBinder extends Binder{
public BindService getService(){
return BindService.this;
}
}
//通過binder實現了 調用者（client）與 service之間的通信
private MyBinder binder = new MyBinder();
2、在onBind方法中返回IBinder實例，返回實例可以是Service實例本身 或者 通過binder暴露出Service公共方法。通常情況下，就是講binder弄成Service內部類，然後在binder中創建一個類似getService的方法並返回包含binder的Service對象，如上面那種情況，這樣client（客戶端）可以通過該方法得到相應的Service實例
接著 調用者（client客戶端）執行的流程
1、先創建ServiceConnetion實例，並重寫其方法，如下面所示：
//創建ServiceConnection類型的實例
private ServiceConnection conn = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
isBound = true;
BindService.MyBinder binder = (BindService.MyBinder) service;
bindService = binder.getService();
int num = bindService.getRandomNumber();
Log.v("hjz","numA="+num);
}
//client 和service連接意外丟失時，會調用該方法
@Override
public void onServiceDisconnected(ComponentName name) {
Log.v("hjz","onServiceDisconnected A");
}
};
這是因為使用bindServer中使用到該對象，bindServer源碼
@Override
public boolean bindService(Intent service, ServiceConnection conn,
int flags) {//調用bindServer，發現第二個傳參就是ServiceConnection對象
return mBase.bindService(service, conn, flags);
}
3、client和Service解除綁定時，onServiceDisconnected並不會被調用；onServiceDisconnected被調用的情況是發生在client和Service連接意外丟失時，這時client和Service一定是斷開連接了。
同個app間調用（多次調用該服務）
BinderAcivityB
public class BinderActivityB extends Activity implements View.OnClickListener {
private Button btn1;
private Button btn2;
private Button btn4;
private BindService bindService = null;
private boolean isBound = false;
private ServiceConnection conn = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
isBound = true;
BindService.MyBinder binder = (BindService.MyBinder) service;
bindService = binder.getService();
int num = bindService.getRandomNumber();
Log.v("hjz","numB="+num);
}
@Override
public void onServiceDisconnected(ComponentName name) {
Log.v("hjz","onServiceDisconnected B");
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_binder_b);
findLayoutView();
setLister();
initData();
}
private void findLayoutView() {
btn1 = (Button) findViewById(R.id.btn1);
btn2 = (Button) findViewById(R.id.btn2);
btn4 = (Button) findViewById(R.id.btn4);
}
private void setLister() {
btn1.setOnClickListener(this);
btn2.setOnClickListener(this);
btn4.setOnClickListener(this);
}
private void initData() {
}
@Override
public void onClick(View v) {
Intent intent = null;
switch (v.getId()){
case R.id.btn1:
intent = new Intent(BinderActivityB.this, BindService.class);
intent.putExtra("from", "ActivityB");
bindService(intent,conn,BIND_AUTO_CREATE);
break;
case R.id.btn2:
if (isBound){
isBound = false;
Log.v("hjz","ActicityB is unbindService");
unbindService(conn);
}
break;
case R.id.btn4:
this.finish();
break;
}
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.i("hjz", "ActivityB -> onDestroy");
}
}
在binderA中， 點擊 binderA綁定→跳轉BinderAcitivityB→binderB綁定→binderB解綁→BinderB finish→BinderA解綁→BinderA finish 的日志
07-09 13:16:10.030 8593-8593/com.hh.servicedemo I/hjz: BindService -> onCreate, Thread: main 07-09 13:16:10.030 8593-8593/com.hh.servicedemo I/hjz: BindService -> onBind, Thread: main 07-09 13:16:10.050 8593-8593/com.hh.servicedemo V/hjz: numA=665064614 07-09 13:16:13.650 8593-8593/com.hh.servicedemo V/hjz: numB=1116469133 07-09 13:16:16.550 8593-8593/com.hh.servicedemo V/hjz: ActicityB is unbindService 07-09 13:16:18.680 8593-8593/com.hh.servicedemo I/hjz: ActivityB -> onDestroy 07-09 13:16:22.920 8593-8593/com.hh.servicedemo V/hjz: ActicityA is unbindService 07-09 13:16:22.930 8593-8593/com.hh.servicedemo I/hjz: BindService -> onUnbind, from:ActivityA 07-09 13:16:22.950 8593-8593/com.hh.servicedemo I/hjz: BindService -> onDestroy, Thread: main 07-09 13:16:25.660 8593-8593/com.hh.servicedemo I/hjz: ActivityA -> onDestroy
從打印日志中發現
在client（客戶端）調用Service【同一個Service】情況下：
如果Service不存在，Service執行順序是onCreate→onBind，接著client創建ServiceConnection實例並執行onServiceConnected這個方法。
如果Service已處於運行狀態【說明在此之前已經在其他地方啟動過該Service】，由於之前執行過的onBind回調獲取IBinder實例，該IBinder實例在所有的client（客戶端）之間是共享的，所以第二次執行onBind回調，直接使用上次已經獲取的IBinder實例，並將其傳入到與之對應的onServiceConnected方法中，標志著連接已經建立了起來，這時就有兩個或者多個client（客戶端）和Service綁定了。
client（客戶端）執行unbindServie的流程：
client與Service解除綁定時，Service先檢測是否還與其他client（客戶端）與其連接→
如果沒有，Service執行onUnbind方法，然後在執行onDestroy方法
如果有，Service不會執行onUnbind和onDestroy方法（從打印的日志中可以得出這樣結論）
點擊 binderA綁定→跳轉BinderAcitivityB→binderB綁定→binderB解綁→BinderB finish→BinderA finish 的日志
07-09 13:19:58.340 8297-8297/com.hh.servicedemo I/hjz: BindService -> onCreate, Thread: main 07-09 13:19:58.360 8297-8297/com.hh.servicedemo I/hjz: BindService -> onBind, Thread: main 07-09 13:19:58.360 8297-8297/com.hh.servicedemo V/hjz: numA=2026321547 07-09 13:20:02.190 8297-8297/com.hh.servicedemo V/hjz: numB=-1586530569 07-09 13:20:04.140 8297-8297/com.hh.servicedemo V/hjz: ActicityB is unbindService 07-09 13:20:05.820 8297-8297/com.hh.servicedemo I/hjz: ActivityB -> onDestroy 07-09 13:20:07.080 8297-8297/com.hh.servicedemo I/hjz: ActivityA -> onDestroy 07-09 13:20:07.110 8297-8297/com.hh.servicedemo I/hjz: BindService -> onUnbind, from:ActivityA 07-09 13:20:07.110 8297-8297/com.hh.servicedemo I/hjz: BindService -> onDestroy, Thread: main
結論：當client與Service通過bindServer連接起來之後，如果client（客戶端）執行（onDestroy）銷毀，那麼client會自動與Service解除綁定。
點擊 binderA綁定→跳轉BinderAcitivityB→binderB綁定→BinderB finish→BinderA解綁→BinderA finish 的日志
07-09 13:17:40.320 8297-8297/com.hh.servicedemo I/hjz: BindService -> onCreate, Thread: main 07-09 13:17:40.320 8297-8297/com.hh.servicedemo I/hjz: BindService -> onBind, Thread: main 07-09 13:17:40.340 8297-8297/com.hh.servicedemo V/hjz: numA=-1117645606 07-09 13:17:43.460 8297-8297/com.hh.servicedemo V/hjz: numB=1774346322 07-09 13:17:44.770 8297-8297/com.hh.servicedemo I/hjz: ActivityB -> onDestroy 07-09 13:17:56.780 8297-8297/com.hh.servicedemo V/hjz: ActicityA is unbindService 07-09 13:17:56.780 8297-8297/com.hh.servicedemo I/hjz: BindService -> onUnbind, from:ActivityA 07-09 13:17:56.780 8297-8297/com.hh.servicedemo I/hjz: BindService -> onDestroy, Thread: main 07-09 13:17:58.060 8297-8297/com.hh.servicedemo I/hjz: ActivityA -> onDestroy
07-09 13:21:22.890 8297-8297/com.hh.servicedemo I/hjz: BindService -> onCreate, Thread: main 07-09 13:21:22.890 8297-8297/com.hh.servicedemo I/hjz: BindService -> onBind, Thread: main 07-09 13:21:22.900 8297-8297/com.hh.servicedemo V/hjz: numA=1947324308 07-09 13:21:26.630 8297-8297/com.hh.servicedemo V/hjz: numB=-1343649013 07-09 13:21:27.730 8297-8297/com.hh.servicedemo I/hjz: ActivityB -> onDestroy 07-09 13:21:29.040 8297-8297/com.hh.servicedemo I/hjz: ActivityA -> onDestroy 07-09 13:21:29.060 8297-8297/com.hh.servicedemo I/hjz: BindService -> onUnbind, from:ActivityA 07-09 13:21:29.060 8297-8297/com.hh.servicedemo I/hjz: BindService -> onDestroy, Thread: main
上面的日志打印，下面用一張圖來總結一下client和Service操作流程：
在不同app之間調用這裡就不做介紹了，有興趣的自己可以去研究一下
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