一、簡介
- Android 四大組件之一（Activity、Service、Broadcast Receiver、Content Provider）
- 一般都是后臺執行，一般用于處于邏輯（Activity前臺，與用戶交互）
- 一旦啟動會一直運行，除非主動停止
- 優先級比較低（優先級低的，在內存不足時被系統優先考慮回收）
- 服務的代碼默認在主線程中執行（和Activity是同一線程，因此，一般在服務的每個具體方法里開啟一個線程，處理耗時邏輯）
二、啟動&停止服務
public class MyService extends Service{
private static final String TAG = "MyService";
public MyService() {
}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
// return mBinder;
}
/**
* 服務創建時調用
*/
@Override
public void onCreate() {
super.onCreate();
Log.d(TAG, "onCreate: ");
}
/**
* 每次服務啟動時調用
*/
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand: ");
return super.onStartCommand(intent, flags, startId);
}
/**
* 服務銷毀時調用
*/
@Override
public void onDestroy() {
super.onDestroy();
Log.d(TAG, "onDestroy: ");
}
}
case R.id.btn_start_service:
Intent startIntent = new Intent(this, MyService.class);
startService(startIntent);
break;
case R.id.btn_stop_service:
Intent stopIntent = new Intent(this, MyService.class);
stopService(stopIntent);
break;
運行結果
啟動服務：
D/MyService: onCreate executed
D/MyService: onStartCommand:
停止服務：
D/MyService: onDestroy:
三、服務和活動通信
package com.example.jony.servicedemo;
import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
import android.util.Log;
public class MyService extends Service{
private static final String TAG = "MyService";
private DownloadBinder mBinder = new DownloadBinder();
class DownloadBinder extends Binder {
public void startDownload(){
Log.d(TAG, "startDownload: ");
}
public int getProgress() {
Log.d(TAG, "getProgress: ");
return 0;
}
}
public MyService() {
}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
// throw new UnsupportedOperationException("Not yet implemented");
return mBinder;
}
/**
* 服務創建時調用
*/
@Override
public void onCreate() {
super.onCreate();
Log.d(TAG, "onCreate: ");
}
/**
* 每次服務啟動時調用
*/
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand: ");
return super.onStartCommand(intent, flags, startId);
}
/**
* 服務銷毀時調用
*/
@Override
public void onDestroy() {
super.onDestroy();
Log.d(TAG, "onDestroy: ");
}
}
package com.example.jony.servicedemo;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.IBinder;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private MyService.DownloadBinder downloadBinder;
private ServiceConnection connection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
downloadBinder = (MyService.DownloadBinder) iBinder;
downloadBinder.startDownload();
downloadBinder.getProgress();
}
@Override
public void onServiceDisconnected(ComponentName componentName) {
}
};
private Button btn_start_service;
private Button btn_stop_service;
private Button btn_bind_service;
private Button btn_unbind_service;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn_start_service = (Button) findViewById(R.id.btn_start_service);
btn_stop_service = (Button) findViewById(R.id.btn_stop_service);
btn_bind_service = (Button) findViewById(R.id.btn_bind_service);
btn_unbind_service = (Button) findViewById(R.id.btn_unbind_service);
btn_stop_service.setOnClickListener(this);
btn_start_service.setOnClickListener(this);
btn_bind_service.setOnClickListener(this);
btn_unbind_service.setOnClickListener(this);
}
@Override
public void onClick(View view) {
switch (view.getId()){
case R.id.btn_start_service:
Intent startIntent = new Intent(this, MyService.class);
startService(startIntent);
break;
case R.id.btn_stop_service:
Intent stopIntent = new Intent(this, MyService.class);
stopService(stopIntent);
break;
case R.id.btn_bind_service:
Intent bindIntent = new Intent(this, MyService.class);
bindService(bindIntent, connection, BIND_AUTO_CREATE);
break;
case R.id.btn_unbind_service:
unbindService(connection);
break;
default:
break;
}
}
}
運行結果
綁定：
D/MyService: onCreate executed
D/MyService: startDownload:
D/MyService: getProgress:
解綁：
onDestroy:
四、服務的生命周期
一圖解萬道
網絡圖片—服務的生命周期.png
五、前臺服務
@Override
public void onCreate() {
super.onCreate();
Log.d(TAG, "onCreate executed");
Intent intent = new Intent(this, MainActivity.class);
PendingIntent pi = PendingIntent.getActivities(this, 0, new Intent[]{intent}, 0);
Notification notification = new NotificationCompat.Builder(this)
.setContentTitle("this is content title")
.setContentText("this is connect text")
.setWhen(System.currentTimeMillis())
.setSmallIcon(R.mipmap.ic_launcher)
.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher))
.setContentIntent(pi)
.build();
startForeground(1, notification);
}
執行結果：
圖片.png
六、IntentService
服務的代碼默認在主線程中執行，所以在服務里面處理耗時操作的時候，容易出現ANR，所以應該在服務的每個具體方法里開啟一個子線程，用來處理耗時的邏輯操作。
由于服務一旦開啟，就會一直處于運行狀態，所以必須調用stopSelf()或stopService()方法停服務。
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand: ");
new Thread(new Runnable() {
@Override
public void run() {
//處理邏輯操作
stopSelf();
}
}).start();
return super.onStartCommand(intent, flags, startId);
}
因此Android專門提供了IntentService類。
public class MyIntentService extends IntentService {
private static final String TAG = "MyIntentService";
public MyIntentService() {
//調用父類的有參構造方法
super("MyIntentService");
}
@Override
protected void onHandleIntent(@Nullable Intent intent) {
//打印當前線程id
Log.d(TAG, "onHandleIntent: Thread id is "+Thread.currentThread().getId());
}
@Override
public void onDestroy() {
super.onDestroy();
Log.d(TAG, "onDestroy executed");
}
}
開啟服務，intentService執行完后會自動停止。
case R.id.btn_start_intentService:
Log.d(TAG, "Thread id is "+Thread.currentThread().getId());
Intent intentService = new Intent(this, MyIntentService.class);
startService(intentService);
break;
運行結果：
D/MainActivity: Thread id is 1
D/MyIntentService: onHandleIntent: Thread id is 337
D/MyIntentService: onDestroy executed
參考：Android Service 服務（一）—— Service
Android Service完全解析，關于服務你所需知道的一切(上)
圖片.png
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.jony.servicedemo.MainActivity"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="start&stop Service"/>
<Button
android:id="@+id/btn_start_service"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Start service"/>
<Button
android:id="@+id/btn_stop_service"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Stop service"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="bind&unbind Service"/>
<Button
android:id="@+id/btn_bind_service"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Bind service"/>
<Button
android:id="@+id/btn_unbind_service"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Unbind service"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="start&stop IntentService"/>
<Button
android:id="@+id/btn_start_intentService"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="start intentService"/>
</LinearLayout>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.jony.servicedemo">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service
android:name=".MyService"
android:enabled="true"
android:exported="true"></service>
<!--<service android:name=".MyIntentService" />-->
</application>
</manifest>
