ServicesJintin

AGENDA

Definition

LifeCycle

Method

Manifest

Service Family

Close to You

Comparison

Q&A

Definition

Application Components

Activities

Services

Content Providers

Broadcast Receivers

What is not a Service..

not a separate process

not a Thread

What a Service is..

long running operation in background

no UI interaction

What a Service is..Context

Context Wrapper

Activity

ContextIml

Service

ContextThemeWrappe

Lifecycle

Two way Lifecycle

startService

bindService

both..

StartService

start by other Application Component (such like Activity, Service..) who calling startService

destroy by calling stopService() or stopSelf()

BindService

bind when Application Component calling bindService()

unbind when calling unbindService()

provide IBinder to interact with other component

when none is bind, the service destroy

Methods

Callback Methods

onStartCommand()

onBind()

onCreate()

onDestroy()

onStartCommand()

when Service is start by calling startService(), onStartCommand will be called

the Service will indefinitely running

you have to call stopSelf() or stopService() to destroy Service

onStartCommand()

wrap original onStart() before 2.0

return an Integer to indicate which behaviour to do when System killed it

onBind()

help to bind Service and other Application Component by ServiceConnection

return a IBinder instance to interact with other Component

return null to not allow binding

Service Connection

onServiceConnected (ComponentName name,IBinder service)

onServiceDisConnected (ComponentName name)

onCreate()

called before onStartCommand() and onBind()

won’t call if Service is already running

onDestroy()

called when the service is no longer used

should clean up all the resource such as thread, listener, receivers

Stop a Service

stopService(Intent intent)

stopSelf()

stopSelf(int startId)

Manifest

Manifest<manifest ... > ... <application ... > <service android:name=".MyService" /> ... </application> </manifest>

Manifest

support Intent Filter for implicit-Intent call

android:exported=”false” to forbid implicit-Intent call

Service Family

Intent Service

extends Service

auto generate worker thread

generate work queue to avoid multi-threading

Intent Service

auto stop Service when all request is done

default onBind() return null

default onStartCommand() redirect to onHandleIntent()

Close to You

Notify User

Toast Notifications

Status Bar Notifications

Foreground Service

more actively aware

less opportunity to been killed

startForeground() bind with an Notification for the status bar to interact with the user

like music player

Comparison

Service VS Activity

no UI

won’t killed when screen rotate

Process important hierarchy (killing priority)

more..

Service VS Thread

Main Thread or not

Context embedded

more..

Service VS Intent Service

Intent Service provide Worker queue that only allow one Thread to execute one time

more..

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