android本地后台服务示例

在android编写Service入门中介绍了android的两种后台服务，本地和远程的。这里用本地服务做了一个模拟定时后台发短信的技术原型。

启动该示例应用的样子：





 

选择启动：





启动后，可看到ddms logcat日志：





这是操作：启动、停止和退出应用，显示的调试日志信息。模拟后台服务每5秒钟发送一次短信信息。

主要代码，后台服务SmsService：

package com.easymorse;

import android.app.Service;

import android.content.Intent;

import android.os.Binder;

import android.os.IBinder;

import android.util.Log;

public class SmsService extends Service {

    private boolean started;

    private boolean threadDisable;

    private ServiceBinder serviceBinder = new ServiceBinder();

    public class ServiceBinder extends Binder implements ISmsService {

        @Override

        public boolean isStarted() {

            return started;

        }

        @Override

        public void start() {

            started=true;

            Log.d(“sms.service”, “sms service started.”);

        }

        @Override

        public void stop() {

            started=false;

            Log.d(“sms.service”, “sms service stopped.”);

        }

    }

    @Override

    public IBinder onBind(Intent intent) {

        return serviceBinder;

    }

    @Override

    public void onCreate() {

        super.onCreate();

        Thread thread = new Thread() {

            @Override

            public void run() {

                while (!threadDisable) {

                    try {

                        if (started) {

                            Log.d(“sms.service”, “send a sms message.”);

                        }

                        Thread.sleep(1000 * 5);

                    } catch (InterruptedException e) {

                    }

                }

            }

        };

        thread.start();

        Log.d(“sms.service”, “sms service created.”);

    }

    @Override

    public void onDestroy() {

        super.onDestroy();

        threadDisable = true;

        Log.d(“sms.service”, “sms service shutdown.”);

    }

}

 

前台的Actvity代码，SmsServiceOptions：

package com.easymorse;

import android.app.TabActivity;

import android.content.ComponentName;

import android.content.Intent;

import android.content.ServiceConnection;

import android.os.Bundle;

import android.os.IBinder;

import android.util.Log;

import android.widget.RadioGroup;

import android.widget.TabHost;

import android.widget.RadioGroup.OnCheckedChangeListener;

public class SmsServiceOptions extends TabActivity {

    private RadioGroup radioGroup;

    private ISmsService smsService;

    private ServiceConnection serviceConnection = new ServiceConnection() {

        @Override

        public void onServiceConnected(ComponentName name, IBinder service) {

            smsService = (ISmsService) service;

            if (smsService.isStarted()) {

                radioGroup.check(R.id.radioButtonStart);

            } else {

                radioGroup.check(R.id.radioButtonStop);

            }

            radioGroup

                    .setOnCheckedChangeListener(new OnCheckedChangeListener() {

                        @Override

                        public void onCheckedChanged(RadioGroup group,

                                int checkedId) {

                            if (checkedId == R.id.radioButtonStart) {

                                Log.d(“sms.service”, “starting service…”);

                                smsService.start();

                            } else {

                                Log.d(“sms.service”, “stopping service…”);

                                smsService.stop();

                            }

                        }

                    });

        }

        @Override

        public void onServiceDisconnected(ComponentName name) {

            smsService = null;

        }

    };

    /** Called when the activity is first created. */

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        this.setTitle(“短信服务器”);

        this.bindService(new Intent(“com.easymorse.SmsService”),

                this.serviceConnection, BIND_AUTO_CREATE);

        TabHost tabHost = this.getTabHost();

        tabHost.setup();

        TabHost.TabSpec spec = tabHost.newTabSpec(“服务选项”);

        spec.setContent(R.id.Option01);

        spec.setIndicator(“服务选项”);

        tabHost.addTab(spec);

        spec = tabHost.newTabSpec(“服务状态”);

        spec.setContent(R.id.Option02);

        spec.setIndicator(“服务状态”);

        tabHost.addTab(spec);

        radioGroup = (RadioGroup) this.findViewById(R.id.radioGroup01);

    }

    @Override

    protected void onDestroy() {

        super.onDestroy();

        this.unbindService(serviceConnection);

    }

}

 

另外，不要忘记在配置文件中增加对service的声明，见AndroidManafest.xml：

<?xml version=”1.0″ encoding=”utf-8″?>

<manifest xmlns:android=”http://schemas.android.com/apk/res/android”

    package=”com.easymorse” android:versionCode=”1″ android:versionName=”1.0″>

    <application android:icon=”@drawable/icon” android:label=”@string/app_name”>

        <activity android:name=”.SmsServiceOptions” android:label=”@string/app_name”>

            <intent-filter>

                <action android:name=”android.intent.action.MAIN” />

                <category android:name=”android.intent.category.LAUNCHER” />

            </intent-filter>

        </activity>

        <service android:name=”.SmsService”>

            <intent-filter>

                <action android:name=”com.easymorse.SmsService”></action>

            </intent-filter>

        </service>

    </application>

    <uses-sdk android:minSdkVersion=”3″ />

</manifest>

 

源代码见：

http://easymorse.googlecode.com/svn/tags/android.local.service.1.demo/

这个示例的局限性在于，如果Activity退出，则后台服务也一起退出。本地服务是否可以在Activity退出后依然在后台执行，还需要进一步了解android api。我猜测应该是不可以的，本地服务和Activity可能是同一个进程的不同线程关系。