Android中Service使用bindService
前面已经对Service的startServer方式启动一个服务了解过了，现在来看一下Service的另一种启动方式→bindServer
bindServer使用场景
1、在同个app之间调用（即是同一个进程中）
2、在不同app之间调用（即是跨进程间通信）
同个app间调用（只有一次启动该服务）
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连接意外丢失时，会调用该方法
@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
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="vertical"
tools:context="com.hh.servicedemo.MainActivity">
<Button
android:id="@+id/btn1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="BinderService绑定"/>
<Button
android:id="@+id/btn2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="BinderService解绑"/>
<Button
android:id="@+id/btn3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="跳转到BinderActivityB"/>
<Button
android:id="@+id/btn4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="finish"/>
</LinearLayout>
BinderService
public class BindService extends Service {
public class MyBinder extends Binder{
public BindService getService(){
return BindService.this;
}
}
//通过binder实现了 调用者（client）与 service之间的通信
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调用
public int getRandomNumber(){
return generator.nextInt();
}
}
点击BinderService绑定，再点击BinderService解绑，最后点击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
点击BinderService绑定，再点击finish
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
1、先得到相应的binder对象，可以在Service内部用内部类得到相应的binder，如下所示：
public class MyBinder extends Binder{
public BindService getService(){
return BindService.this;
}
}
//通过binder实现了 调用者（client）与 service之间的通信
private MyBinder binder = new MyBinder();2、在onBind方法中返回IBinder实例，返回实例可以是Service实例本身 或者 通过binder暴露出Service公共方法。通常情况下，就是讲binder弄成Service内部类，然后在binder中创建一个类似getService的方法并返回包含binder的Service对象，如上面那种情况，这样client（客户端）可以通过该方法得到相应的Service实例
接着 调用者（client客户端）执行的流程
1、先创建ServiceConnetion实例，并重写其方法，如下面所示：
//创建ServiceConnection类型的实例
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连接意外丢失时，会调用该方法
@Override
public void onServiceDisconnected(ComponentName name) {
Log.v("hjz","onServiceDisconnected A");
}
};这是因为使用bindServer中使用到该对象，bindServer源码
@Override
public boolean bindService(Intent service, ServiceConnection conn,
int flags) {//调用bindServer，发现第二个传参就是ServiceConnection对象
return mBase.bindService(service, conn, flags);
}
2、当执行了onServiceConnected回调时，我们可以通过IBinder实例得到Service实例对象 或 直接调用binder公共方法，这样就实现了client和service的连接
3、client和Service解除绑定时，onServiceDisconnected并不会被调用；onServiceDisconnected被调用的情况是发生在client和Service连接意外丢失时，这时client和Service一定是断开连接了。
同个app间调用（多次调用该服务）
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， 点击 binderA绑定→跳转BinderAcitivityB→binderB绑定→binderB解绑→BinderB finish→BinderA解绑→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
从打印日志中发现
在client（客户端）调用Service【同一个Service】情况下：
如果Service不存在，Service执行顺序是onCreate→onBind，接着client创建ServiceConnection实例并执行onServiceConnected这个方法。
如果Service已处于运行状态【说明在此之前已经在其他地方启动过该Service】，由于之前执行过的onBind回调获取IBinder实例，该IBinder实例在所有的client（客户端）之间是共享的，所以第二次执行onBind回调，直接使用上次已经获取的IBinder实例，并将其传入到与之对应的onServiceConnected方法中，标志着连接已经建立了起来，这时就有两个或者多个client（客户端）和Service绑定了。
client（客户端）执行unbindServie的流程：
client与Service解除绑定时，Service先检测是否还与其他client（客户端）与其连接→
如果没有，Service执行onUnbind方法，然后在执行onDestroy方法
如果有，Service不会执行onUnbind和onDestroy方法（从打印的日志中可以得出这样结论）
点击 binderA绑定→跳转BinderAcitivityB→binderB绑定→binderB解绑→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
结论：当client与Service通过bindServer连接起来之后，如果client（客户端）执行（onDestroy）销毁，那么client会自动与Service解除绑定。
点击 binderA绑定→跳转BinderAcitivityB→binderB绑定→BinderB finish→BinderA解绑→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
点击 binderA绑定→跳转BinderAcitivityB→binderB绑定→BinderB finish→BinderA finish 的日志
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，下面用一张图来总结一下client和Service操作流程：
在不同app之间调用这里就不做介绍了，有兴趣的自己可以去研究一下