Google Service
1. 在前台运行服务
- 前台服务是用户主动意识到的一种服务，因此在内存不足时，系统也不会考虑将其终止
- 前台服务必须为状态栏提供通知，将其放在运行中的标题下方
- 对于前台服务,除非将服务停止或从前台移除，否则不能清除该通知
- 台服务必须显示优先级为 PRIORITY_LOW 或更高 的状态栏通知
2. 服务的生命周期
- Service.stopSelf()
- 同Context.stopService
/** * Stop the service, if it was previously started. This is the same as * calling {@link android.content.Context#stopService} for this particular service. * * @see #stopSelfResult(int) */ public final void stopSelf() { stopSelf(-1); } - Context.stopService()
- stopService注释可印证上面图片.startService创建的Service,后续又执行bindService,直接执行stopService,不能直接销毁Service.要先unbind,再stopService.
/**
* 如果stopService之前通过bindService + BIND_AUTO_CREATE,已经生成了 ServiceConnection ,
* 则所有调用过bindService的客户端都执行unbind之前,该Service不会被销毁.
*
* Note that if a stopped service still has {@link ServiceConnection}
* objects bound to it with the {@link #BIND_AUTO_CREATE} set, it will
* not be destroyed until all of these bindings are removed.
*/
public abstract boolean stopService(Intent service);
3. 绑定服务概览/重点是其生命周期
4. 各种异常
1. java.lang.IllegalStateException: Not allowed to start service Intent
- 异常
AndroidRuntime: java.lang.IllegalStateException: Not allowed to start service Intent { cmp=**/.**Service (has extras) }: app is in background uid UidRecord{***} AndroidRuntime: at android.app.ContextImpl.startServiceCommon(ContextImpl.java:1831) AndroidRuntime: at android.app.ContextImpl.startService(ContextImpl.java:1771) AndroidRuntime: at android.content.ContextWrapper.startService(ContextWrapper.java:720) AndroidRuntime: at android.content.ContextWrapper.startService(ContextWrapper.java:720) AndroidRuntime: at com.**.**Activity$9.run(SourceFile:1657) 10-12 11:22:55.018 7403 9203 E AndroidRuntime: at java.lang.Thread.run(Thread.java:923) - 源码中触发位置
frameworks/base/core/java/android/app/ContextImpl.java private ComponentName startServiceCommon(Intent service, boolean requireForeground, UserHandle user) { try { validateServiceIntent(service); service.prepareToLeaveProcess(this); ComponentName cn = ActivityManager.getService().startService( mMainThread.getApplicationThread(), service, service.resolveTypeIfNeeded(getContentResolver()), requireForeground, getOpPackageName(), getAttributionTag(), user.getIdentifier()); if (cn != null) { if (cn.getPackageName().equals("!")) { throw new SecurityException( "Not allowed to start service " + service + " without permission " + cn.getClassName()); } else if (cn.getPackageName().equals("!!")) { throw new SecurityException( "Unable to start service " + service + ": " + cn.getClassName()); } else if (cn.getPackageName().equals("?")) { //是在这儿抛出了异常 throw new IllegalStateException( "Not allowed to start service " + service + ": " + cn.getClassName()); } } return cn; } catch (RemoteException e) { throw e.rethrowFromSystemServer(); } } - 具体原因:解决java.lang.IllegalStateException: Not allowed to start service Intent xxxx app is in background u
- 解决方案
Android 8.0 的应用尝试在不允许其创建后台服务的情况下使用 startService() 函数，则该函数将引发一个 IllegalStateException。
新的 Context.startForegroundService() 函数将启动一个前台服务。现在，即使应用在后台运行，系统也允许其调用 Context.startForegroundService()。
不过，应用必须在创建服务后的五秒内调用该服务的 startForeground() 函数。
1:startService调用端添加版本判断,使用不同API
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
context.startForegroundService(new Intent(context, CustomService.class));
} else {
context.startService(new Intent(context, CustomService.class));
}
2:CustomService必须在onCreate添加对应判断,>=0情况下展示通知栏/前台服务
@Override
public void onCreate() {
super.onCreate();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
Notification noti = gainNotificationViaIntent(getIntent());
startForeground(1,noti);
}
}
5. Binder
上次没砍我的,这次我又来了。看完这篇还不明白Binder你砍我
6. aidl
- aidl文件中不要加中文注释,AS会报错.
- 在新版AS里面创建aidl文件,会报错
- 关闭AS,再重新打开,发现aidl中的文件是乱码,修改一下就好了.
- 关闭前,aidl文件的内容看着正常,build就会报错,日了.
