Android四大组件之Service示例

一个很简单的service示例，没有太多要讲解的。

有一个地方需要注意的是getRunningServices 已经被google标记为deprecated, 所以对于27（oreo）及以后的版本，如果要达到类似效果，可以使用isMyServiceRunning来代替isRunning()，如例子中所标记的那样。

我这里使用的是stopService来停止service，作为示例，其中也使用了stopSelf。

使用stopSelf(startId)的话，startID就是onStartCommand所传进来的那个。在service创建实例之后，每startService一次，这个startID就会+1。当stopService->onDestroy运行之后，不管有多少个Thread在运行，全部都会终止，如下图所示，

下面是本例全部的源码，

AndroidManifest.xml

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

</manifest>

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"
    android:padding="20dp"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/bt_start"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/start_service"/>

    <Button
        android:id="@+id/bt_stop"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/stop_service"/>
</LinearLayout>

MainActivity.java

package com.spacesoftwares.servicedemo;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    private Button mBtnStart;
    private Button mBtnStop;
    private Intent intent;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mBtnStart = findViewById(R.id.bt_start);
        mBtnStop = findViewById(R.id.bt_stop);
        setListener();
    }

    private void setListener(){
        OnClick onClick = new OnClick();
        mBtnStart.setOnClickListener(onClick);
        mBtnStop.setOnClickListener(onClick);
    }

    private class  OnClick implements View.OnClickListener{

        @Override
        public void onClick(View view) {
            int view_id = view.getId();

            if(view_id == R.id.bt_start){
                if(null == intent)
                    intent = new Intent(MainActivity.this, MyService.class);
                startService(intent);
                MyService.isMyServiceRunning = true;
            }else if(view_id == R.id.bt_stop){
                if(null != intent){
                    stopService(intent);
                    MyService.isMyServiceRunning = false;
                }
            }
        }
    }
}

MyService.java

package com.spacesoftwares.servicedemo;

import android.app.Activity;
import android.app.ActivityManager;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;

import java.util.ArrayList;

public class MyService extends Service {

    public static boolean isMyServiceRunning = false;

    public MyService() {
    }

    private String TAG = "MyService";
    @Override
    public void onCreate() {
        super.onCreate();
        Log.i(TAG, "service created");
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.i(TAG, "service start command");
        new Thread(new Runnable() {
            @Override
            public void run() {
                int i = 0;

                while(isRunning()) // or, you can use while(isMyServiceRunning) here instead of isRunning
                {
                    Log.i(TAG, "SERVICE IS RUNNING for " + String.valueOf(i++) + " seconds");
                    try {
                        Thread.sleep(1000);
                    }catch (InterruptedException e){
                        e.printStackTrace();
                    }
                }
            }
        }).start();
        return super.onStartCommand(intent, flags, startId);
    }

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

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

    // 请注意getRunningServices 已经标记为deprecated, 如果要达到类似效果，请使用isMyServiceRunning来代替isRunning()
    public boolean isRunning(){
        ActivityManager activityManager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
        ArrayList<ActivityManager.RunningServiceInfo> runningService =
                (ArrayList<ActivityManager.RunningServiceInfo>) activityManager.getRunningServices(40);
        for(int i=0; i<runningService.size();i++){
            String name = runningService.get(i).service.getClassName().toString();
            if(name.equals("com.spacesoftwares.servicedemo.MyService")){
                return true;
            }
        }
        return  false;
    }
}

res->values->strings.xml

<resources>
    <string name="app_name">ServiceDemo</string>
    <string name="start_service">StartServiceDemo</string>
    <string name="stop_service">StopServiceDemo</string>
</resources>