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Service

Service(服务)是一个后台运行的组件，执行长时间运行且不需要用户交互的任务。即使应用被销毁也依然可以工作。服务的两种启动状态

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要创建服务，需要创建一个继承自Service基类或者它的已知子类的Java类。

Service基类定义了不同的回调方法和多数重要方法。你不需要实现所有的回调方法。

Started方式实战

修改AndroidManifest.xml文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"package="com.example.user.service"><applicationandroid: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" /></application></manifest>

添加<service android:name=".MyService" />这句话.

增加MyService.java代码:

package com.example.user.service;import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.widget.Toast;public class MyService extends Service {@Overridepublic IBinder onBind(Intent arg0) {return null;}@Overridepublic int onStartCommand(Intent intent, int flags, int startId) {// Let it continue running until it is stopped.Toast.makeText(this, "服务已经启动", Toast.LENGTH_LONG).show();return START_STICKY;}@Overridepublic void onDestroy() {super.onDestroy();Toast.makeText(this, "服务已经停止", Toast.LENGTH_LONG).show();}
}

修改MainActivity.java代码:

package com.example.user.service;import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;public class MainActivity extends AppCompatActivity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);}// Method to start the servicepublic void startService(View view) {startService(new Intent(getBaseContext(), MyService.class));}// Method to stop the servicepublic void stopService(View view) {stopService(new Intent(getBaseContext(), MyService.class));}
}

修改activity_main.xml文件:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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=".MainActivity"><Buttonandroid:id="@+id/button2"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginStart="137dp"android:layout_marginTop="57dp"android:layout_marginEnd="159dp"android:layout_marginBottom="253dp"android:onClick="startService"android:text="启动服务"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@+id/button" /><Buttonandroid:id="@+id/button"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginStart="137dp"android:layout_marginTop="105dp"android:layout_marginEnd="159dp"android:layout_marginBottom="57dp"android:onClick="stopService"android:text="停止服务"app:layout_constraintBottom_toTopOf="@+id/button2"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toTopOf="parent" /></android.support.constraint.ConstraintLayout>

运行效果:

image.png

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Bound方式实战

修改AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"package="com.example.user.service"><applicationandroid: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><serviceandroid:name=".MyService"android:enabled="true"android:exported="true"></service></application></manifest>

创建MyService.java:

package com.example.user.service;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 MyBinder binder = new MyBinder();private int count = 0;public class MyBinder extends Binder{public int getCount(){return count;}}@Overridepublic IBinder onBind(Intent intent) {// TODO: Return the communication channel to the service.Log.d("test","Service onBinder.");return binder;}@Overridepublic void onCreate() {super.onCreate();Log.d("test","Service onCreate.");count++;}@Overridepublic boolean onUnbind(Intent intent){Log.d("test","Service onUnbind");return true;}@Overridepublic void onDestroy(){super.onDestroy();Log.d("test","Service onDestroy");}
}

修改MainActivity.java:

package com.example.user.service;import android.app.Service;
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.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;public class MainActivity extends AppCompatActivity {Button b1,b2,getCon;MyService.MyBinder binder;private ServiceConnection conn = new ServiceConnection() {@Overridepublic void onServiceConnected(ComponentName name, IBinder service) {Log.d("test","--service connect--");binder = (MyService.MyBinder)service;}@Overridepublic void onServiceDisconnected(ComponentName name) {Log.d("test","--service disconnect--");}};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);b1 = (Button) findViewById(R.id.button1);b2 = (Button) findViewById(R.id.button2);getCon = (Button) findViewById(R.id.button3);final Intent intent = new Intent(this, MyService.class);b1.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {bindService(intent, conn, Service.BIND_AUTO_CREATE);}});b2.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {unbindService(conn);}});getCon.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {Toast.makeText(MainActivity.this,"count:"+binder.getCount(),Toast.LENGTH_SHORT).show();}});}
}

修改activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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=".MainActivity"><Buttonandroid:id="@+id/button1"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginStart="148dp"android:layout_marginTop="77dp"android:layout_marginEnd="148dp"android:layout_marginBottom="95dp"android:text="start"app:layout_constraintBottom_toTopOf="@+id/button2"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toTopOf="parent" /><Buttonandroid:id="@+id/button2"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginStart="148dp"android:layout_marginTop="95dp"android:layout_marginEnd="148dp"android:layout_marginBottom="243dp"android:text="stop"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@+id/button1" /><Buttonandroid:id="@+id/button3"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginStart="148dp"android:layout_marginTop="78dp"android:layout_marginEnd="148dp"android:layout_marginBottom="85dp"android:text="GetStatus"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@+id/button2" />
</android.support.constraint.ConstraintLayout>

执行结果:

image.png

2020-06-28 16:36:15.052 8758-8758/com.example.user.service D/test: Service onCreate.
2020-06-28 16:36:15.054 8758-8758/com.example.user.service D/test: Service onBinder.
2020-06-28 16:36:15.056 8758-8758/com.example.user.service D/test: --service connect--
2020-06-28 16:36:40.249 8758-8780/com.example.user.service D/EGL_emulation: eglMakeCurrent: 0xebc57240: ver 2 0 (tinfo 0xebc036c0)
2020-06-28 16:36:40.257 8758-8780/com.example.user.service D/EGL_emulation: eglMakeCurrent: 0xebc57240: ver 2 0 (tinfo 0xebc036c0)
2020-06-28 16:37:27.518 8758-8758/com.example.user.service D/test: Service onUnbind
2020-06-28 16:37:27.518 8758-8758/com.example.user.service D/test: Service onDestroy