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