java - 沮丧.. lastLocation.getLatitude() 将设置文本但不会启动双重。为此使用 google api

Question

所以我整天都在为此工作，我快要失去理智了。我正在尝试从谷歌的位置 api 获取坐标，以便从另一个 api (forcast.io) 获取天气。我的代码已经达到这样的程度，即 google api 正在使用正确的坐标完美地设置我的 TextViews ...但是当我尝试将这些坐标分配给将被获取并作为 http 链接发送到 forcast.io 的值时... lat 和 long 的值为 0.0。我不知道这笔交易是什么。在 onConnected() 方法中初始化它们后，我尝试从我的 TextViews 中获取文本作为字符串，我尝试在 onConnected() 方法中将值初始化为 double ...我已经完成了我所做的一切可以想到。这是我的代码:

package com.gardnerwebideas.myweather;

import android.content.Context;
import android.location.Location;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationServices;
import com.squareup.okhttp.Call;
import com.squareup.okhttp.Callback;
import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.Response;

import java.io.IOException;

public class MainActivity extends AppCompatActivity
        implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener {


    private static final String TAG = MainActivity.class.getSimpleName();
    private GoogleApiClient mGoogleApiClient;
    private Location mLastLocation;
    private double mLatitude;
    private double mLongitude;
    private TextView mLatitudeText;
    private TextView mLongitudeText;




//----------------------GOOGLE API BUILD----------------------------
    protected synchronized void buildGoogleApiClient() {
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();

    }




//--------------------ON CREATE METHOD--------------------------------
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mLatitudeText = (TextView) findViewById(R.id.latitudeText);
        mLongitudeText = (TextView) findViewById(R.id.longitudeText);

        buildGoogleApiClient();
        mGoogleApiClient.connect();




//---------------------CODE FROM ANDROID PROJECT-----------------------
//----------------SETTING UP NETWORK AND WEATHER API-------------------
        String APIKey = "71e3dbfb4ebeb4dc3bcfb07097bb3645";
        String forecastUrl = "https://api.forecast.io/forecast/"
                + APIKey + "/"
                + mLatitude
                + ","
                + mLongitude;
        if (isNetworkAvailable()) {
            OkHttpClient client = new OkHttpClient();
            Request request = new Request.Builder()
                    .url(forecastUrl)
                    .build();

            Call call = client.newCall(request);
            call.enqueue(new Callback() {
                @Override
                public void onFailure(Request request, IOException e) {

                }

                @Override
                public void onResponse(Response response) throws IOException {
                    try {
                        if (response.isSuccessful()) {
                            Log.v(TAG, response.body().string());
                        } else {
                            alertUserAboutError();
                        }
                    } catch (IOException e) {
                        Log.e(TAG, "Exception caught: ", e);
                    }
                }
            });
        } else {
            Toast.makeText(this, "Network Unavailable", Toast.LENGTH_LONG).show();
        }
        Log.d(TAG, "Main UI code is running!");
    }




//------------------------NETWORK METHODS-------------------------------
    private boolean isNetworkAvailable() {
        ConnectivityManager manager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = manager.getActiveNetworkInfo();
        boolean isAvailable = false;
        if (networkInfo != null && networkInfo.isConnected()) {
           isAvailable = true;
        }
        return isAvailable;
    }

    private void alertUserAboutError() {
        AlertDialogFragment dialog = new AlertDialogFragment();
        dialog.show(getFragmentManager(), "error_dialogue");
    }




//------------------------GOOGLE API CODE-------------------------------
    @Override
    public void onConnected(Bundle bundle) {
        mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
        if (mLastLocation != null) {
            mLatitudeText.setText(String.valueOf(mLastLocation.getLatitude()));
            mLongitudeText.setText(String.valueOf(mLastLocation.getLongitude()));
            mLatitude = mLastLocation.getLatitude();
            mLongitude = mLastLocation.getLongitude();
        }
    }

    @Override
    public void onConnectionSuspended(int i) {

    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {

    }
}

Answer 1

您遗漏了一个关键点:地理位置信息以异步方式处理。在您的代码中，这意味着有关您的地理位置的信息将在您调用 forecast.io 之后 可用，这就是为什么您总是看到 0 值的原因。

只需按照以下方式更新您的代码(查看方法 callForecastAPI):

import android.content.Context;
import android.location.Location;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.TextView;
import android.widget.Toast;

import com.example.ziby.testing.R;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationServices;
import com.squareup.okhttp.Call;
import com.squareup.okhttp.Callback;
import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.Response;

import java.io.IOException;

public class MainActivity extends AppCompatActivity
        implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener {


    private static final String TAG = MainActivity.class.getSimpleName();
    private GoogleApiClient mGoogleApiClient;
    private Location mLastLocation;
    private double mLatitude;
    private double mLongitude;
    private TextView mLatitudeText;
    private TextView mLongitudeText;




    //----------------------GOOGLE API BUILD----------------------------
    protected synchronized void buildGoogleApiClient() {
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();

    }




    //--------------------ON CREATE METHOD--------------------------------
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mLatitudeText = (TextView) findViewById(R.id.latitudeText);
        mLongitudeText = (TextView) findViewById(R.id.longitudeText);

        buildGoogleApiClient();
        mGoogleApiClient.connect();
        Log.d(TAG, "Main UI code is running!");
    }

    private void callForecastAPI(){
        String APIKey = "71e3dbfb4ebeb4dc3bcfb07097bb3645";
        String forecastUrl = "https://api.forecast.io/forecast/"
                + APIKey + "/"
                + mLatitude
                + ","
                + mLongitude;
        if (isNetworkAvailable()) {
            OkHttpClient client = new OkHttpClient();
            Request request = new Request.Builder()
                    .url(forecastUrl)
                    .build();

            Call call = client.newCall(request);
            call.enqueue(new Callback() {
                @Override
                public void onFailure(Request request, IOException e) {

                }

                @Override
                public void onResponse(Response response) throws IOException {
                    try {
                        if (response.isSuccessful()) {
                            Log.v(TAG, response.body().string());
                        } else {
                            alertUserAboutError();
                        }
                    } catch (IOException e) {
                        Log.e(TAG, "Exception caught: ", e);
                    }
                }
            });
        } else {
            Toast.makeText(this, "Network Unavailable", Toast.LENGTH_LONG).show();
        }
    }



    //------------------------NETWORK METHODS-------------------------------
    private boolean isNetworkAvailable() {
        ConnectivityManager manager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = manager.getActiveNetworkInfo();
        boolean isAvailable = false;
        if (networkInfo != null && networkInfo.isConnected()) {
            isAvailable = true;
        }
        return isAvailable;
    }

    private void alertUserAboutError() {
        AlertDialogFragment dialog = new AlertDialogFragment();
        dialog.show(getFragmentManager(), "error_dialogue");
    }




    //------------------------GOOGLE API CODE-------------------------------
    @Override
    public void onConnected(Bundle bundle) {
        mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
        if (mLastLocation != null) {
            mLatitudeText.setText(String.valueOf(mLastLocation.getLatitude()));
            mLongitudeText.setText(String.valueOf(mLastLocation.getLongitude()));
            mLatitude = mLastLocation.getLatitude();
            mLongitude = mLastLocation.getLongitude();
            callForecastAPI(); //call the forecast API when you get the location
        }
    }

    @Override
    public void onConnectionSuspended(int i) {

    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {

    }
}