通过短信发送GPS坐标

Question

我是android新手。我试图开发一个应用程序，获取用户当前的GPS坐标，并通过短信发送到硬编码的数字。我正在使用两项活动，第一项有一个进度条和一些文字（处理，请稍候），它实际上是在后台获取GPS坐标。第二个是从第一个活动接收坐标并发送短信。我面临的问题是，在MainActivity.java文件中，条件if（latitude> 0）永远不会被满足，因为gps通常需要一些时间才能获得坐标，而我不能转到第二个活动。我附上代码，请帮助我。如果你喜欢，你可以编辑代码。 在此先感谢。

package com.shaji.smartcab; 

import com.shaji.smartcab.MainActivity; 
import com.shaji.smartcab.MyLocationListener; 
import com.shaji.smartcab.R; 


import android.os.Bundle; 
import android.app.Activity; 

import android.view.Menu; 
import android.widget.TextView; 
import android.widget.Toast; 
import android.location.LocationListener; 
import android.content.Context; 
import android.content.Intent; 
import android.location.LocationManager; 


public class MainActivity extends Activiy{ 
double lat; 
double lon; 
String coordinates; 
String coor; 


@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    TextView tv= (TextView) findViewById(R.id.textView1); 



      LocationManager mlocManager=null; 
      LocationListener mlocListener; 
      mlocManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE); 
      mlocListener = new MyLocationListener(); 
      mlocManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 600,10, mlocListener); 



     if (mlocManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) { 



       if(MyLocationListener.latitude>0) { 
       lat = MyLocationListener.latitude; 
       lon = MyLocationListener.longitude; 
       tv.setText("m fetching coordinates"); 

       coordinates= lat+","+lon; 

     Intent intent = new Intent(MainActivity.this, Sec.class); 
     intent.putExtra(coor, coordinates); 
     startActivity(intent); 






       //tv1.setText("Latitude:" + MyLocationListener.latitude + ",Longitude:" + MyLocationListener.longitude); 
       }} 



       else { 
        Context context = getApplicationContext(); 
        CharSequence text = "Please turn ON GPS and Try again Later!"; 
        int duration = Toast.LENGTH_SHORT; 

        Toast toast = Toast.makeText(context, text, duration); 
        toast.show(); 
        tv.setText(" "); 

       } 


    }; 

@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.main, menu); 
    return true; 
}} 

enter code here package com.shaji.smartcab;

import android.location.Location; 
import android.location.LocationListener; 
import android.os.Bundle; 

public class MyLocationListener implements LocationListener { 

public static double latitude; 
public static double longitude; 

@Override 
public void onLocationChanged(Location loc) 
{ 

    loc.getLatitude(); 
    loc.getLongitude(); 
    latitude=loc.getLatitude(); 
    longitude=loc.getLongitude(); 


} 

@Override 
public void onProviderDisabled(String provider) 
{ 
    //print "Currently GPS is Disabled"; 
} 
@Override 
public void onProviderEnabled(String provider) 
{ 
    //print "GPS got Enabled"; 
} 
@Override 
public void onStatusChanged(String provider, int status, Bundle extras) 
{ 
} 
} 




//this is the second activity. 
package com.shaji.smartcab; 
import com.shaji.smartcab.R; 

import android.app.Activity; 
import android.os.Bundle; 
import android.telephony.SmsManager; 
import android.view.View; 
import android.widget.Button; 
import android.widget.Toast; 

public class Sec extends Activity { 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    // TODO Auto-generated method stub 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.second); 



    final String sms = (String) getIntent().getExtras().get("coor"); 
    Button c = (Button) findViewById(R.id.button1); 
    c.setOnClickListener(new View.OnClickListener() { 

     @Override 
     public void onClick(View arg0) { 

      String phoneNo = "03136166588"; 
       //String sms = "coordinates"; 

       try { 
             SmsManager smsManager = SmsManager.getDefault(); 
             smsManager.sendTextMessage(phoneNo, null, sms, null, null); 
             Toast.makeText(getApplicationContext(), "Request Sent!", 
               Toast.LENGTH_LONG).show(); 
            } catch (Exception e) { 
             Toast.makeText(getApplicationContext(), 
               " Error, please try again later!", 
               Toast.LENGTH_LONG).show(); 
             e.printStackTrace(); 

     } 

     }}); 


}} 

Answer 1

我认为问题是，在调用下一个活动之前没有完成位置更新。

在获得更新之前，使用3个提供者之一获取坐标。请参阅以下代码。

private Location getUserLocation() { 

location_manager = (LocationManager) getSystemService(LOCATION_SERVICE); 
if (location_manager != null) { 

    List<String > provider=location_manager .getAllProviders(); 
      Location location = null; 
      for(int i=0;i<provider.size();i++){ 
       location=location_manager .getLastKnownLocation(provider.get(i)); 
       if(location!=null){ 
          location_manager.requestLocationUpdates(provider.get(i), 
                MIN_TIME_BW_UPDATES, 
                MIN_DISTANCE_CHANGE_FOR_UPDATES,mlocListener); 
         break; 
         } 
      } 


return location; 

} 
}