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我正在构建一个简单的 android 应用程序，它需要我自动更新位置。自动更新位置不仅会在恢复应用程序时更新，而且必须在应用程序打开时自动更新。这个应用程序看起来与放在车内的 GPS 系统相同。它获取确切位置并始终更新当前位置。我想在这里做同样的事情。我正在 android 2.2 上构建这个应用程序。

这是我的代码：

 package com.example.map;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.widget.TextView;
import android.widget.Toast;

public class MapActivity extends Activity implements LocationListener{
    private TextView latituteField, longitudeField, accuracyField, altitudeField, bearingField; 
    private LocationManager locationManager;
    private String provider;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_map);

    latituteField = (TextView) findViewById(R.id.TextView02);
    longitudeField = (TextView) findViewById(R.id.TextView04);
    accuracyField = (TextView) findViewById(R.id.textView1);
    altitudeField = (TextView) findViewById(R.id.textView2);
    bearingField = (TextView) findViewById(R.id.textView4);

    // Get the location manager
    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    // Define the criteria how to select the locatioin provider -> use default  
    Criteria criteria = new Criteria();
    provider = locationManager.getBestProvider(criteria, false);
    Location location = locationManager.getLastKnownLocation(provider);


    // Initialize the location fields
    if (location != null) {
      System.out.println("Provider " + provider + " has been selected.");
      onLocationChanged(location);
    } else {
      latituteField.setText("Location not available");
      longitudeField.setText("Location not available");
    }
  }

  /* Request updates at startup */
  @Override
  protected void onResume() {
    super.onResume();
    locationManager.requestLocationUpdates(provider, 400, 1, this);
  }

  /* Remove the locationlistener updates when Activity is paused */
  @Override
  protected void onPause() {
    super.onPause();
    locationManager.removeUpdates(this);
  }

  @Override
  public void onLocationChanged(Location location) {
    int lat = (int) (location.getLatitude());
    int lng = (int) (location.getLongitude());
    int acc = (int) (location.getAccuracy());
    int alt = (int) (location.getAltitude());
    int bearing = (int) (location.getBearing());
    latituteField.setText(String.valueOf(lat));
    longitudeField.setText(String.valueOf(lng));
    accuracyField.setText(String.valueOf(acc));
    altitudeField.setText(String.valueOf(alt));
    bearingField.setText(String.valueOf(bearing));

  }

  @Override
  public void onStatusChanged(String provider, int status, Bundle extras) {
    // TODO Auto-generated method stub

  }

  @Override
  public void onProviderEnabled(String provider) {
    Toast.makeText(this, "Enabled new provider " + provider,
        Toast.LENGTH_SHORT).show();

  }

  @Override
  public void onProviderDisabled(String provider) {
    Toast.makeText(this, "Disabled provider " + provider,
        Toast.LENGTH_SHORT).show();
  }

此代码仅在我恢复应用程序时更新位置值（我退出应用程序然后返回应用程序）。该位置将在视图文本中更新。

我也试着做一会儿。像这样。

if(location != null){
    do{
        System.out.println("Provider " + provider + " has been selected.");
        onLocationChanged(location);
        locationManager.requestLocationUpdates(provider, 0, 0, this);
    }while(location != null);
    }
    else{
        latituteField.setText("Location not available");
        longitudeField.setText("Location not available");
    }

我将此添加到清单中。

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

但是，此代码会使应用程序在真实手机中崩溃。有没有办法完成这项工作？

*注意：我在我的真实手机中测试了所有这个应用程序并试图达到当前位置。文本视图假设只要它获得位置的新值而不暂停或退出应用程序就会改变。

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1 回答 1

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您必须将您的位置代码放在 ScheduledExecutor 服务中：

http://developer.android.com/reference/java/util/concurrent/ScheduledExecutorService.html

那个在后台重复实现功能，例如每 30 秒或您指定的任何时间。

例子：

    scheduleTaskExecutor= Executors.newScheduledThreadPool(5);

    // This schedule a task to run every 10 seconds:

    scheduleTaskExecutor.scheduleAtFixedRate(new Runnable() {
      public void run() {


            try {                 


                //add your code you would like to be executed every 10 seconds.



            } catch (IOException e) {                          
               e.printStackTrace();                           
            }                                     


      }
    }, 0, 10, TimeUnit.SECONDS);

您可能还需要为粗略位置添加权限。

于 2012-09-27T05:22:00.690 回答