我在这里遇到了一些问题，需要一些帮助。
我想获得已经实现的给定坐标的位置地址。 我的项目检查互联网连接，如果连接不可用，应用程序将显示警告对话框，使用“重试”或“手动”配置。 多数民众赞成工作正常，但在我从wifi或移动数据连接启用互联网连接后，该应用程序获得了fc，因为空指针异常。
我已经在真实设备中进行了测试，经过如此多的尝试，它正常工作。 我如何告诉手机连接并检测到正在建立连接然后等待连接建立，然后成功加载其数据？
在我的示例中，我的手机启用了wifi无线电，但我设法在WPA2握手完成之前启动我的Activity。片刻之后我重新开始我的活动，因为wifi链接已经建立，所以没有问题。但我希望能够检测到wifi链接实际上正在尝试连接，并等待它连接。 这是我的应用程序的代码：
import java.io.File;
import java.io.IOException;
import java.util.List;
import java.util.Locale;
import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.ContentResolver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.graphics.Bitmap;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.net.ConnectivityManager;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;
public class db_new_auto extends Activity {
/**
* Best location abstract result class
*/
public static abstract class LocationResult{
public abstract void gotLocation(Location location);
}
public class MyLocation{
Timer timer1;
LocationManager lm;
LocationResult locationResult;
boolean gps_enabled=false;
boolean network_enabled=false;
public boolean getLocation(Context context, LocationResult result)
{
//I use LocationResult callback class to pass location value from MyLocation to user code.
locationResult=result;
if(lm==null)
lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
//exceptions will be thrown if provider is not permitted.
try{gps_enabled=lm.isProviderEnabled(LocationManager.GPS_PROVIDER);}catch(Exception ex){}
try{network_enabled=lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER);}catch(Exception ex){}
//don't start listeners if no provider is enabled
if(!gps_enabled && !network_enabled)
return false;
if(gps_enabled)
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListenerGps);
if(network_enabled)
lm.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListenerNetwork);
timer1=new Timer();
timer1.schedule(new GetLastLocation(), 20000);
return true;
}
LocationListener locationListenerGps = new LocationListener() {
public void onLocationChanged(Location location) {
timer1.cancel();
locationResult.gotLocation(location);
lm.removeUpdates(this);
lm.removeUpdates(locationListenerNetwork);
}
public void onProviderDisabled(String provider) {}
public void onProviderEnabled(String provider) {}
public void onStatusChanged(String provider, int status, Bundle extras) {}
};
LocationListener locationListenerNetwork = new LocationListener() {
public void onLocationChanged(Location location) {
timer1.cancel();
locationResult.gotLocation(location);
lm.removeUpdates(this);
lm.removeUpdates(locationListenerGps);
}
public void onProviderDisabled(String provider) {}
public void onProviderEnabled(String provider) {}
public void onStatusChanged(String provider, int status, Bundle extras) {}
};
class GetLastLocation extends TimerTask {
@Override
public void run() {
lm.removeUpdates(locationListenerGps);
lm.removeUpdates(locationListenerNetwork);
Location net_loc=null, gps_loc=null;
if(gps_enabled)
gps_loc=lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if(network_enabled)
net_loc=lm.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
//if there are both values use the latest one
if(gps_loc!=null && net_loc!=null){
if(gps_loc.getTime()>net_loc.getTime())
locationResult.gotLocation(gps_loc);
else
locationResult.gotLocation(net_loc);
return;
}
if(gps_loc!=null){
locationResult.gotLocation(gps_loc);
return;
}
if(net_loc!=null){
locationResult.gotLocation(net_loc);
return;
}
locationResult.gotLocation(null);
}
}
}
// the text fields that users input new data into
EditText etNama, etKabupaten,etJalan, etLong, etLat, etKeterangan;
// the buttons that listen for the user to select an action
Button bSave, bCancel;
ImageView ivAddpicture;
// the class that opens or creates the database and makes sql calls to it
PuraHelper helper;
ProgressDialog dialog;
Location currentLocation;
double currentLatitude;
double currentLongitude;
//private static final int IMAGE_CAPTURE = 0;
private static final int TAKE_PICTURE = 0;
private Uri imageUri;
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.tab_new);
dialog = ProgressDialog.show(db_new_auto.this, "Getting Location",
"Loading, Please wait...", true);
MyLocation myLocation = new MyLocation();
myLocation.getLocation(this, locationResult);
// create the database manager object
helper = new PuraHelper(this);
ivAddpicture = (ImageView)findViewById(R.id.ivAddpicture);
etNama = (EditText)findViewById(R.id.etNama);
//etKabupaten = (EditText)findViewById(R.id.etKabupaten);
etJalan = (EditText)findViewById(R.id.etJalan);
etLong = (EditText)findViewById(R.id.etLong);
etLat = (EditText)findViewById(R.id.etLat);
etKeterangan = (EditText)findViewById(R.id.etKeterangan);
bSave=(Button)findViewById(R.id.bSave);
bCancel=(Button)findViewById(R.id.bCancel);
ivAddpicture.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
addPicture();
}
});
bCancel.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
startActivity(new Intent(db_new_auto.this, db_list.class));
}
});
bSave.setOnClickListener(onSave);
}
private View.OnClickListener onSave=new View.OnClickListener() {
public void onClick(View v) {
helper.insert(etNama.getText().toString(),
//etKabupaten.getText().toString(),
etJalan.getText().toString(),
etLong.getText().toString(),
etLat.getText().toString(),
etKeterangan.getText().toString());
Intent iDatabase = new Intent(getBaseContext(),db_list.class);
startActivityForResult(iDatabase,0);
}
};
protected void addPicture() {
// TODO Auto-generated method stub
final CharSequence[] items = {"Camera", "Galery"};
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Add picture from?");
builder.setIcon(R.drawable.ic_setting_36);
builder.setSingleChoiceItems(items, -1, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int item) {
if (items[item]=="Camera") {
//startActivity(new Intent(db_new_auto.this, cam.class));
//startCamera();
takePhoto(ivAddpicture);
}
else if(items[item]=="Galery"){
}
finish();
}
});
AlertDialog alert = builder.create();
alert.show();
}
public void takePhoto(View view) {
// TODO Auto-generated method stub
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
File photo = new File(Environment.getExternalStorageDirectory(), "Pic.jpg");
intent.putExtra(MediaStore.EXTRA_OUTPUT,
Uri.fromFile(photo));
imageUri = Uri.fromFile(photo);
startActivityForResult(intent, TAKE_PICTURE);
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
switch (requestCode) {
case TAKE_PICTURE:
if (resultCode == Activity.RESULT_OK) {
Uri selectedImage = imageUri;
getContentResolver().notifyChange(selectedImage, null);
ImageView imageView = (ImageView) findViewById(R.id.ivAddpicture);
ContentResolver cr = getContentResolver();
Bitmap bitmap;
try {
bitmap = android.provider.MediaStore.Images.Media
.getBitmap(cr, selectedImage);
imageView.setImageBitmap(bitmap);
Toast.makeText(this, selectedImage.toString(),
Toast.LENGTH_LONG).show();
} catch (Exception e) {
Toast.makeText(this, "Failed to load", Toast.LENGTH_SHORT)
.show();
Log.e("Camera", e.toString());
}
}
}
}
/*
protected void startCamera() {
// TODO Auto-generated method stub
Log.d("ANDRO_CAMERA", "Starting camera on the phone...");
String fileName = "testphoto.jpg";
ContentValues values = new ContentValues();
values.put(MediaStore.Images.Media.TITLE, fileName);
values.put(MediaStore.Images.Media.DESCRIPTION,
"Image capture by camera");
values.put(MediaStore.Images.Media.MIME_TYPE, "image/jpeg");
imageUri = getContentResolver().insert(
MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
intent.putExtra(MediaStore.EXTRA_VIDEO_QUALITY, 1);
startActivityForResult(intent, IMAGE_CAPTURE);
}
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == IMAGE_CAPTURE) {
if (resultCode == RESULT_OK){
Log.d("ANDRO_CAMERA","Picture taken!!!");
ivAddpicture.setImageURI(imageUri);
}
}
}
*/
public LocationResult locationResult = new LocationResult(){
private Address location;
@Override
public void gotLocation(final Location location){
// do something
double lng = location.getLongitude();
double lat = location.getLatitude();
etLat.setText(""+lng);
etLong.setText(""+lat);
dialog.dismiss();
checkinternetconnection();
}
private boolean checkinternetconnection() {
// TODO Auto-generated method stub
ConnectivityManager conMgr = (ConnectivityManager) getSystemService (Context.CONNECTIVITY_SERVICE);
// ARE WE CONNECTED TO THE NET
if (conMgr.getActiveNetworkInfo() != null
&& conMgr.getActiveNetworkInfo().isAvailable()
&& conMgr.getActiveNetworkInfo().isConnected()) {
double lng = location.getLongitude();
double lat = location.getLatitude();
Geocoder gcd = new Geocoder(getBaseContext(), Locale.getDefault());
List<Address> addresses = null;
try {
addresses = gcd.getFromLocation(lat, lng, 1);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String address = "";
if (addresses.size() > 0) {
for (int index = 0;
index < addresses.get(0).getMaxAddressLineIndex(); index++)
address += addresses.get(0).getAddressLine(index) + " ";
etJalan.setText(address);
}
return true;
}
else {
Toast.makeText(getBaseContext(), "No Internet Connection", Toast.LENGTH_SHORT).show();
alertRetry();
return false;
}
}
};
protected void alertRetry() {
// TODO Auto-generated method stub
final CharSequence[] items = {"Rety", "Use Manual"};
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Cannot get current location");
builder.setIcon(R.drawable.ic_setting_36);
builder.setSingleChoiceItems(items, -1, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int item) {
if (items[item]=="Rety") {
startActivity(new Intent(db_new_auto.this, db_new_auto.class));
}
else if(items[item]=="Use Manual"){
startActivity(new Intent(db_new_auto.this, db_new_man.class));
}
finish();
}
});
AlertDialog alert = builder.create();
alert.show();
}
}
答案 0 :(得分：0)
您可以询问手机是否正在连接：
final ConnectivityManager connMgr = (ConnectivityManager)
ctx.getSystemService(Context.CONNECTIVITY_SERVICE);
final android.net.NetworkInfo wifi =
connMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
final android.net.NetworkInfo mobile =
connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
final android.net.NetworkInfo network = connMgr.getActiveNetworkInfo();
if (!network.isConnected() && network.isConnectedOrConnecting()) {
// trying to connect..sleep for a few or put up a dialog and use a Handler()
}