Android 互联网连接可用时，从BoadCastereceiver发送纬度和经度

我想发送JSON字符串

{
    "latitude": 53.86898504,
    "longitude": 10.66561187,
    "time": "25.04.2015 11:37:11",
    "route": 4
} 

每60秒发送一次到服务器，因此当我尝试从internet连接广播接收器发送JSON字符串时，JSON字符串在那里为空，但当我从onLocationChanged方法发送数据时，我在PostData类中获取字符串，但如果internet不可用，我希望在internet连接可用时发送数据如果可用，我将短时间存储字符串。如何实现它以在CONNECTIVITY\u ACTION BroadcastReceiver中获取JSONString

谢谢你的帮助

主要活动类别：

public class MainActivity extends ActionBarActivity {

Location location;
LocationManager locationManager;
String jSONString;

    TextView textJSON;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textJSON = (TextView) findViewById(R.id.textJSON);


        LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        LocationListener ll = new myLocationListener();
        lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10000, 0, ll);


    }

    private class BroadcastReceiverListener extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            if (intent.getAction().equals(
                    android.net.wifi.WifiManager.SCAN_RESULTS_AVAILABLE_ACTION)) {
                     //code to get the strongest wifi access point in the JSON string the routes's value.
            }

            else if (intent.getAction().equals(
                    android.net.ConnectivityManager.CONNECTIVITY_ACTION)) {

                ConnectivityManager connectivityManager = (ConnectivityManager) context
                        .getSystemService(Context.CONNECTIVITY_SERVICE);

                NetworkInfo netInfo = connectivityManager
                        .getActiveNetworkInfo();

                boolean isConnected = netInfo != null
                        && netInfo.isConnectedOrConnecting();
                if (isConnected) {
                    Toast.makeText(context,
                            "The device is connected to the internet ",
                            Toast.LENGTH_SHORT).show();
                if (location == null) {

                    Location locat = locationManager
                            .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                    if (locat == null) {

                        LocationListener locLis = new myLocationListener();
                        LocationManager locMan = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
                        Criteria criteria = new Criteria();
                        Looper myLooper = Looper.myLooper();

                        locMan.requestSingleUpdate(criteria, locLis,
                                myLooper);

                    } else {
                        System.out.println("locat is not null");
                    }

                } else {
                    PostData sender = new PostData();
                    sender.timer(jSONString);
                    textJSON.setText(jSONString);
                }


                } else {
                    Toast.makeText(context,
                            "Please connect the device to the internet.",
                            Toast.LENGTH_SHORT).show();
                }

            }
        }

    }

    class myLocationListener implements LocationListener {

        @Override
        public void onLocationChanged(Location location) {

            if (location != null) {
                double pLong = location.getLongitude();
                double pLat = location.getLatitude();
                ...
                String time = sdf.format(location.getTime());

                jSONString = convertToJSON(pLong, pLat, time);
                System.out.println("The output of onLocationChanged: "+ jSONString);

                //The code works fine here. JSON string has its values here but in broadcastReceiver JSON string has null.
//              PostData sender = new PostData();
//              sender.timer(jSONString);
//              textJSON.setText(jSONString);



            }
        }
    }
}

希望这会有所帮助

每当BroadCastReceiver触发时，首先检查

位置

（实例变量）是否为

null

如果

location

为空，则通过调用

getLastKnownLocation（LocationManager.GPS\u PROVIDER）

获取位置，返回位置或空值

如果

getLastKnownLocation（）

return

null

发出单个位置更新请求

requestSingleUpdate（条件、位置侦听器侦听器、活套器）

检查侦听器回调

---

看起来，您可以通过添加一个额外的标志作为实例变量来确定是否在没有internet的情况下获得位置更新，并将

isConnected

标志作为实例变量来获得所需的行为

如果连接到internet，则每次收到位置更改事件时都要发送位置数据，否则请设置标志并等到有internet连接时再发送上次位置更新的数据

我在问题中使用了您的原始代码并对其进行了修改：

public class MainActivity extends ActionBarActivity {

    int route_number;
    double pLong;
    double pLat;
    String time;
    String jSONString;

    boolean isConnected; //added
    boolean locationUpdatedNoInternet; //added
    long lastLocationTime = 0; //added

    TextView textJSON;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textJSON = (TextView) findViewById(R.id.textJSON);


        LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        LocationListener ll = new myLocationListener();
        lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10000, 0, ll);


    }

    private class BroadcastReceiverListener extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            if (intent.getAction().equals(
                    android.net.wifi.WifiManager.SCAN_RESULTS_AVAILABLE_ACTION)) {
                //code to get the strongest wifi access point in the JSON string the routes's value.
            }

            else if (intent.getAction().equals(
                    android.net.ConnectivityManager.CONNECTIVITY_ACTION)) {

                ConnectivityManager connectivityManager = (ConnectivityManager) context
                        .getSystemService(Context.CONNECTIVITY_SERVICE);

                NetworkInfo netInfo = connectivityManager
                        .getActiveNetworkInfo();

                //set instance variable isConnected here instead of creating local variable
                isConnected = netInfo != null
                        && netInfo.isConnectedOrConnecting();
                //boolean isConnected = netInfo != null
                        //&& netInfo.isConnectedOrConnecting();
                if (isConnected) {
                    Toast.makeText(context,
                            "The device is connected to the internet ",
                            Toast.LENGTH_SHORT).show();

                    //check if we got a location update with no internet
                    long currTime = System.currentTimeMillis();
                    if (locationUpdatedNoInternet == true) {
                        //check that last location send was longer than 5 seconds ago
                        if (lastLocationTime == 0 || ((currTime - lastLocationTime) > 5000 )){
                            lastLocationTime = System.currentTimeMillis(); //set last sent time
                            locationUpdatedNoInternet = false; //re-set to false
                            PostData sender = new PostData();
                            //since we are checking locationUpdatedNoInternet flag, we definitely have location data.
                            System.out.println("The output of internet broadcast: " + jSONString);
                            sender.timer(jSONString);
                            textJSON.setText(jSONString);
                        }
                    }

                } else {
                    Toast.makeText(context,
                            "Please connect the device to the internet.",
                            Toast.LENGTH_SHORT).show();
                }

            }
        }

    }

    class myLocationListener implements LocationListener {

        @Override
        public void onLocationChanged(Location location) {

            if (location != null) {
                pLong = location.getLongitude();
                pLat = location.getLatitude();
                //...
                time = sdf.format(location.getTime());

                jSONString = convertToJSON(pLong, pLat, time);
                System.out.println("The output of onLocationChanged: "+ jSONString);

                long currTime = System.currentTimeMillis();
                if (isConnected == true) {
                    //check that last location send was longer than 5 seconds ago
                    if (lastLocationTime == 0 || ((currTime - lastLocationTime) > 5000 )) {
                        //if connected, just send the data
                        lastLocationTime = System.currentTimeMillis(); //set last sent time
                        locationUpdatedNoInternet = false;
                        PostData sender = new PostData();
                        sender.timer(jSONString);
                        textJSON.setText(jSONString);
                    }
                }
                else{
                    //set flag so that the last location update will be sent once connection is established
                    locationUpdatedNoInternet = true;
                }

            }
        }
    }
}

---

但在internet连接广播服务器中未定义位置。这是否意味着我将使用internet连接BroafdCastereceiver扩展myLocationListener，或者最好扩展我的PostData类？创建

Location-Location

的实例变量（类级别），并在

onLocationChanged

处初始化其值。当BroadCastReceiver为location实例而不是jsonString.please查看我的更新问题时，我按照您所说的那样暗示了它，并且我得到了以下错误：

，原因是：java.lang.NullPointerException:尝试调用虚拟方法'android.location.location.android.location.LocationManager.getLastKnownLocation（java.lang.String）'在空对象引用上

使用前检查位置值

if（location！=null）{}

我注意到在这里使用您的sulotion时，我得到了

sender.timer（jSONString）的输出同时两次！？这是因为sender.timer（jSOnString）在
BroadcastReceiverListener
和
onLocationChanged（）
中被调用了两次吗？@MrAsker是的，这是可能的。如果是这样，您可以在日志中进行验证。一个简单的解决方案是保留上次更新时间的时间戳，并确保自上次更新以来时间已超过5秒。查看更新的答案，查看
lastLocationTime
和
currTime
。请看一下这个问题