Android以後台Service的方式獲取GPRS數據

在配備Android系統的手機中，一般都配備了GPS設備。Android為我們獲取GPS數據提供了很好的接口。本文來說一下如何使用Android獲取GPS的經緯度。

1 從Service繼承一個類。
2 創建startService()方法。
3 創建endService()方法 重載onCreate方法和onDestroy方法，並在這兩個方法裡面來調用startService以及endService。
4 在startService中，通過getSystemService方法獲取Context.LOCATION_SERVICE。
5 基於LocationListener實現一個新類。默認將重載四個方法onLocationChanged、onProviderDisabled、onProviderEnabled、onStatusChanged。對於onLocationChanged方法是我們更新最新的GPS數據的方法。一般我們的操作都只需要在這裡進行處理。
6 調用LocationManager的requestLocationUpdates方法，來定期觸發獲取GPS數據即可。在onLocationChanged函數裡面可以實現我們對得到的經緯度的最終操作。
7 最後在我們的Activity裡面通過按鈕來啟動Service，停止Service。

示意代碼如下：

1. package com.jouhu.gpsservice;
3. import android.app.Service;
4. import android.content.Context;
5. import android.content.Intent;
6. import android.location.LocationListener;
7. import android.location.LocationManager;
8. import android.os.Binder;
9. import android.os.IBinder;
10. import android.util.Log;
12. public class GPSService extends Service {
14. //2000ms
15. private static final long minTime = 2000;
16. //最小變更距離 10m
17. private static final float minDistance = 10;
19. String tag = this.toString();
21. private LocationManager locationManager;
22. private LocationListener locationListener;
24. private final IBinder mBinder = new GPSServiceBinder();
26. public void startService()
27. {
28. locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
29. locationListener = new GPSServiceListener();
30. locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, minTime, minDistance, locationListener);
31. }
33. public void endService()
34. {
35. if(locationManager != null && locationListener != null)
36. {
37. locationManager.removeUpdates(locationListener);
38. }
39. }
41. @Override
42. public IBinder onBind(Intent arg0) {
43. // TODO Auto-generated method stub
44. return mBinder;
45. }
47. @Override
48. public void onCreate()
49. {
50. //
51. startService();
52. Log.v(tag, "GPSService Started.");
53. }
55. @Override
56. public void onDestroy()
57. {
58. endService();
59. Log.v(tag, "GPSService Ended.");
60. }
62. public class GPSServiceBinder extends Binder {
63. GPSService getService() {
64. return GPSService.this;
65. }
66. }
67. }

GPRSServiceListener的實現：

1. package com.jouhu.gpsservice;
3. import java.text.DateFormat;
4. import java.text.SimpleDateFormat;
5. import java.util.Calendar;
6. import java.util.GregorianCalendar;
7. import java.util.TimeZone;
9. import android.location.Location;
10. import android.location.LocationListener;
11. import android.location.LocationProvider;
12. import android.os.Bundle;
13. import android.util.Log;
14. import android.widget.Toast;
16. public class GPSServiceListener implements LocationListener {
18. private static final String tag = "GPSServiceListener";
19. private static final float minAccuracyMeters = 35;
20. private static final String hostUrl = "http://doandroid.info/gpsservice/position.php?";
21. private static final String user = "huzhangyou";
22. private static final String pass = "123456";
23. private static final int duration = 10;
24. private final DateFormat timestampFormat = new SimpleDateFormat("yyyyMMddHHmmss");
26. public int GPSCurrentStatus;
28. @Override
29. public void onLocationChanged(Location location) {
30. // TODO Auto-generated method stub
31. if(location != null)
32. {
33. if (location.hasAccuracy() && location.getAccuracy() <= minAccuracyMeters)
34. {
35. //獲取時間參數,將時間一並Post到服務器端
36. GregorianCalendar greg = new GregorianCalendar();
37. TimeZone tz = greg.getTimeZone();
38. int offset = tz.getOffset(System.currentTimeMillis());
39. greg.add(Calendar.SECOND, (offset/1000) * -1);
40. StringBuffer strBuffer = new StringBuffer();
41. strBuffer.append(hostUrl);
42. strBuffer.append("user=");
43. strBuffer.append(user);
44. strBuffer.append("&pass=");
45. strBuffer.append(pass);
46. strBuffer.append("&Latitude=");
47. strBuffer.append(location.getLatitude());
48. strBuffer.append("&Longitude=");
49. strBuffer.append(location.getLongitude());
50. strBuffer.append("&Time=");
51. strBuffer.append(timestampFormat.format(greg.getTime()));
52. strBuffer.append("&Speed=");
53. strBuffer.append(location.hasSpeed());
54. doGet(strBuffer.toString());
55. Log.v(tag, strBuffer.toString());
56. }
57. }
58. }
60. //將數據通過get的方式發送到服務器,服務器可以根據這個數據進行跟蹤用戶的行走狀態
61. private void doGet(String string) {
62. // TODO Auto-generated method stub
63. //
64. }
66. @Override
67. public void onProviderDisabled(String provider) {
68. // TODO Auto-generated method stub
69. }
71. @Override
72. public void onProviderEnabled(String provider) {
73. // TODO Auto-generated method stub
75. }
77. @Override
78. public void onStatusChanged(String provider, int status, Bundle extras)
79. {
80. // TODO Auto-generated method stub
81. GPSCurrentStatus = status;
82. }
84. }