android通過criteria選擇合適的地理位置服務

 

LocationActivity.java

 

/*  LocationActivity.java

 *  @author octobershiner

 *  2011 7 24

 *  SE.HIT

 *  利用Criteria選擇最優的位置服務，示範定位使用者的位置並且監聽位置變化的代碼

 * */ 

package uni.location; 

 

import android.app.Activity; 

import android.content.Context; 

import android.location.Criteria; 

import android.location.Location; 

import android.location.LocationListener; 

import android.location.LocationManager; 

import android.os.Bundle; 

import android.os.Vibrator; 

import android.util.Log; 

import android.widget.TextView; 

 

public class LocationActivity extends Activity { 

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

    //建立lcoationManager對象 

    private LocationManager manager; 

    private static final String TAG = "LOCATION DEMO"; 

    @Override 

    public void onCreate(Bundle savedInstanceState) { 

        super.onCreate(savedInstanceState); 

        setContentView(R.layout.main); 

        //擷取系統的服務， 

        manager = (LocationManager)getSystemService(Context.LOCATION_SERVICE); 

        //建立一個criteria對象 

        Criteria criteria = new Criteria();    

        criteria.setAccuracy(Criteria.ACCURACY_COARSE); 

        //設定不需要擷取海拔方向資料 

        criteria.setAltitudeRequired(false);    

        criteria.setBearingRequired(false); 

        //設定允許產生資費 

        criteria.setCostAllowed(true);    

        //要求低耗電 

        criteria.setPowerRequirement(Criteria.POWER_LOW);    

        String provider = manager.getBestProvider(criteria, false);    

        Log.i(TAG, "we choose "+ provider); 

        Location location = manager.getLastKnownLocation(provider); 

        //第一次獲得裝置的位置 

        updateLocation(location);    

        //重要函數，監聽資料測試 

        manager.requestLocationUpdates(provider, 6000, 10,    

                       locationListener);    

                        

    }   

     

    //建立一個事件監聽器 

   private final LocationListener locationListener = new LocationListener() {    

            public void onLocationChanged(Location location) {    

            updateLocation(location);    

            }    

            public void onProviderDisabled(String provider){ 

                updateLocation(null);    

                Log.i(TAG, "Provider now is disabled.."); 

            }    

            public void onProviderEnabled(String provider){ 

                Log.i(TAG, "Provider now is enabled.."); 

            }    

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

    };    

     

//擷取使用者位置的函數，利用Log顯示 

    private void updateLocation(Location location) {    

            String latLng;     

            if (location != null) {   

            double lat = location.getLatitude();    

            double lng = location.getLongitude(); 

             

            latLng = "Latitude:" + lat + "  Longitude:" + lng;    

            } else {    

            latLng = "Can't access your location"; 

            } 

            Log.i(TAG, "The location has changed.."); 

            Log.i(TAG, "Your Location:" +latLng); 

    } 

     

} 

 

同時修改manifest.xml檔案

 

<?xml version="1.0" encoding="utf-8"?>   

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

      package="uni.location"   

      android:versionCode="1"   

      android:versionName="1.0">   

    <uses-sdk android:minSdkVersion="8" />   

   

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

        <activity android:name=".LocationActivity"   

                  android:label="@string/app_name">   

            <intent-filter>   

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

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

            </intent-filter>   

        </activity>   

   

    </application>   

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

</manifest>   

 

示範結果：

 

可任看到 我們只要求低的精確度並且最低電量，從最後一行可以看到我的虛擬機器網路服務並沒有開啟，但是選擇最佳provider的時候，參數選擇了false 所以同樣可以選擇。

 

摘自 Octobershiner的專欄