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。