Location acquisition on Android

Location / Context Aware Computing 自90年代開始被廣泛的討論與研究

在 Android 的平台中 , google 提供了兩種獲取 location 資訊的管道

第一個是大家平常較為熟知的 GPS , 然而這裡要分享的則是透過 Wifi 的

Network Location Provider

動作摘要

1. 取得 LocationManager 的 instance

2. 撰寫聽取相關事件的 Listener

3. 註冊事件

// Acquire a reference to the system Location Manager
LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);

// Define a listener that responds to location updates
LocationListener locationListener = new LocationListener() {
   public void onLocationChanged(Location location) {
     // Called when a new location is found by the network location provider.
      makeUseOfNewLocation(location);
   }

   public void onStatusChanged(String provider, int status, Bundle extras) {}

   public void onProviderEnabled(String provider) {}

   public void onProviderDisabled(String provider) {}
 };

// Register the listener with the Location Manager to receive location updates , 
// 第2,3個參數用來控制update的頻率
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListener);

另外必須獲取權限如下：

1. <manifest ... >
      <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
      ...
   manifest>