SystemService(系统服务)

android系统给了我们很多服务，供我们开发使用，譬如，检查网络使用情况，设备电量，SD卡安装或移除，应用的一些信息等等。

简单获取android几个简单的服务

public class MainActivity extends ActionBarActivity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.activity_main);
	}
	public void doClick(View v)
	{
		switch(v.getId())
		{
		case R.id.getvoice:
			AudioManager mAudioManager= (AudioManager) MainActivity.this.getSystemService(AUDIO_SERVICE);
			 int max = mAudioManager.getStreamMaxVolume(AudioManager.STREAM_SYSTEM);//获得系统的最大音量
			 int current = mAudioManager.getStreamVolume(AudioManager.STREAM_RING);//获得当前音量
			 Toast.makeText(MainActivity.this, "系统的最大音量为："+max+",当前音量是："+current, Toast.LENGTH_SHORT).show();
			break;
		case R.id.enableOrDisable_WIFI:
			WifiManager wifiManager =	(WifiManager) MainActivity.this.getSystemService(WIFI_SERVICE);
			if (wifiManager.isWifiEnabled()) {
				//判断是否打开，打开的话就将其关闭
				wifiManager.setWifiEnabled(false);
				Toast.makeText(MainActivity.this, "WIFI已经关闭", Toast.LENGTH_SHORT).show();
			}else {
				//判断是否打开，关闭的话就将其打开
				wifiManager.setWifiEnabled(true);
				Toast.makeText(MainActivity.this, "WIFI已经打开", Toast.LENGTH_SHORT).show();
			}
			break;
		case R.id.getPackagename:
			ActivityManager activityManager = (ActivityManager) MainActivity.this.getSystemService(ACTIVITY_SERVICE);
			String packageName = activityManager.getRunningTasks(1).get(0).topActivity.getPackageName();//获取Activity的包名
			Toast.makeText(MainActivity.this, "当前运行的Activity包名："+packageName, Toast.LENGTH_SHORT).show();
			break;
		case R.id.network:
			if (isNetWorkConnected(MainActivity.this)==true) {
				Toast.makeText(MainActivity.this, "网络已经打开", Toast.LENGTH_SHORT).show();
			}else {
				Toast.makeText(MainActivity.this, "网络未连接", Toast.LENGTH_SHORT).show();
			}
			break;
		}
	}
	private boolean isNetWorkConnected(Context context) {
		// TODO Auto-generated method stub
		if (context != null) {
			ConnectivityManager mConnectivityManager = (ConnectivityManager) context
					.getSystemService(CONNECTIVITY_SERVICE);
			NetworkInfo mNetWorkInfo = mConnectivityManager
					.getActiveNetworkInfo();
			if (mNetWorkInfo != null) {
				return mNetWorkInfo.isAvailable();
			}
		}
		return false;
	}


}

布局根据图片自己随意弄一下，这里就不贴上来啦

}