android8.0以上版本的前台服务

android8.0以上版本的前台服务

本人是小白，最近在学习郭林老师的第一行代码的第二版时，在第10章的前台服务的小节里面，发现在我的模拟器上运行不了，然后找了许多大神写的博客，发现原因是安卓8.0之后的前台服务需要使用startForegroundService（）函数启动服务，然后按照大神的博客里面的步骤做了还不行，然后查看了一下错误日志，
下面是程序崩溃时打印的error日志中的一部分

2018-12-13 11:28:51.156 10945-10945/com.xiaogege.servicetest E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.xiaogege.servicetest, PID: 10945
    java.lang.RuntimeException: Unable to create service com.xiaogege.servicetest.MyService: java.lang.SecurityException: Permission Denial: startForeground from pid=10945, uid=10089 requires android.permission.FOREGROUND_SERVICE
        at android.app.ActivityThread.handleCreateService(ActivityThread.java:3544)
        at android.app.ActivityThread.access$1300(ActivityThread.java:199)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1666)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

发现还要在AndroidManifest申请一下android.permission.FOREGROUND_SERVICE权限,然后就可以正常运行了。

下面是MyService里面的代码

import android.annotation.TargetApi;
import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.Service;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.os.Build;
import android.os.IBinder;
import android.util.Log;

public class MyService extends Service {
    private static final String TAG="MyService";
    private static final String ID="channel_1";
    private static final String NAME="前台服务";

    public MyService() {
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO: Return the communication channel to the service.
        throw new UnsupportedOperationException ("Not yet implemented");
    }

    @Override
    public void onCreate(){
        super.onCreate ();
        Log.d (TAG,"onCreate");
        if(Build.VERSION.SDK_INT>=26){
            setForeground();
        }else{

        }
    }

    @Override
    public void onDestroy(){
        super.onDestroy ();
        Log.d (TAG,"onDestroy");
    }

    @Override
    public int onStartCommand(Intent intent,int flags,int startId){
        Log.d(TAG,"onStartCommand");
        return super.onStartCommand (intent,flags,startId);
    }

    @TargetApi (26)
    private void setForeground(){
        NotificationManager manager=(NotificationManager)getSystemService (NOTIFICATION_SERVICE);
        NotificationChannel channel=new NotificationChannel (ID,NAME,NotificationManager.IMPORTANCE_HIGH);
        manager.createNotificationChannel (channel);
        Notification notification=new Notification.Builder (this,ID)
                .setContentTitle ("收到一条重要通知")
                .setContentText ("这是重要通知")
                .setSmallIcon (R.mipmap.ic_launcher)
                .setLargeIcon (BitmapFactory.decodeResource (getResources (),R.mipmap.ic_launcher))
                .build ();
        startForeground (1,notification);
    }
}

下面是MainActivity里面的代码

import android.content.Intent;
import android.os.Build;
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{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate (savedInstanceState);
        setContentView (R.layout.main_activity_layout);
        Button start=findViewById (R.id.start);
        Button stop=findViewById (R.id.stop);
        start.setOnClickListener (this);
        stop.setOnClickListener (this);
    }

    @Override
    public void onClick(View view){
        switch(view.getId ()){
            case R.id.start:
                Intent start=new Intent (this,MyService.class);
                if(Build.VERSION.SDK_INT>=26){
                    startForegroundService (start);
                }else{
                    startService (start);
                }
                break;
            case R.id.stop:
                Intent stop=new Intent (this,MyService.class);
                stopService (stop);
                break;
            default:
                break;
        }
    }
}

下面是AndroidManifest中的代码

现在再点击开始按钮就可以正常运行了