Issues with GET request using Retrofit in android studio

问题

I'm using Retrofit 2 in Android Studio to get stop information in JSON form from the CUMTD api for stops by search and for some reason the connection keeps on failing, are the query parameters and everything else correct, i used to the JSON to pojo converter for the model class so it should be correct or is it something from main activity? Heres the URL I'm trying to connect to https://developer.cumtd.com/api/v2.2/json/GetStopsBySearch?key=b7cd7d8c64b24b4f8415aeb57d6f7f74&query=transit%20plaza my code:

    import java.util.List;
    import com.google.gson.annotations.Expose;
    import com.google.gson.annotations.SerializedName;

    public class Example {

        @SerializedName("changeset_id")
        @Expose
        private String changesetId;
        @SerializedName("new_changeset")
        @Expose
        private Boolean newChangeset;
        @SerializedName("time")
        @Expose
        private String time;
        @SerializedName("status")
        @Expose
        private Status status;
        @SerializedName("rqst")
        @Expose
        private Rqst rqst;
        @SerializedName("stops")
        @Expose
        private List<Stop> stops = null;

        public String getChangesetId() {
            return changesetId;
        }

        public void setChangesetId(String changesetId) {
            this.changesetId = changesetId;
        }

        public Boolean getNewChangeset() {
            return newChangeset;
        }

        public void setNewChangeset(Boolean newChangeset) {
            this.newChangeset = newChangeset;
        }

        public String getTime() {
            return time;
        }

        public void setTime(String time) {
            this.time = time;
        }

        public Status getStatus() {
            return status;
        }

        public void setStatus(Status status) {
            this.status = status;
        }

        public Rqst getRqst() {
            return rqst;
        }

        public void setRqst(Rqst rqst) {
            this.rqst = rqst;
        }

        public List<Stop> getStops() {
            return stops;
        }

        public void setStops(List<Stop> stops) {
            this.stops = stops;
        }

    }




    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.View;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.TextView;

    import java.util.List;
    import java.util.Random;

    import retrofit2.Call;
    import retrofit2.Callback;
    import retrofit2.Response;

    import static android.R.attr.x;
    import static android.media.CamcorderProfile.get;
    import static com.example.neelpatel.weatherapp.MTDApi.retrofit;

    public class MainActivity extends AppCompatActivity {

        String key= "b7cd7d8c64b24b4f8415aeb57d6f7f74";
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);//Starts Retrofit
            final MTDApi mtdApi = MTDApi.retrofit.create(MTDApi.class);

            //Sets up Button and EditText for use in this class
            final EditText edit = (EditText) findViewById(R.id.edit);
            Button requestButton = (Button) findViewById(R.id.button);

            //Behavior once button is clicked
            requestButton.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {

                    String s = edit.getText().toString();
                    //Sets up up the API call
                    Call<List<Example>> call = mtdApi.loadStops(key,s);

                    //Runs the call on a different thread
                    call.enqueue(new Callback<List<Example>>() {
                        @Override
                        //Once the call has finished

                        public void onResponse(Call<List<Example>> call, Response<List<Example>> response) {
                            if (response.isSuccessful()) {
                                //Gets the list of stops
                                List<Example> stops = response.body();
                                List<Stop> list = stops.get(0).getStops();
                                String text = list.get(0).getStopId();
                                edit.setText(text);
                            } else {
                                // show error message
                                Log.e("RequestCall", "Request failed");
                            }
                        }

                        @Override
                        //If the call failed
                        public void onFailure(Call<List<Example>> call, Throwable t) {
                            edit.setText("Request Failed");
                            Log.e("RequestCall", "Request failed");
                        }
                    });
                }
            });
        }
    }







        import java.util.List;

        import retrofit2.Call;
        import retrofit2.Retrofit;
        import retrofit2.converter.gson.GsonConverterFactory;
        import retrofit2.http.GET;
        import retrofit2.http.Path;
        import retrofit2.http.Query;

        /**
         * Class that details the request(s) that we will call
         */

        public interface MTDApi{
            @GET("GetStopsBySearch")
            Call<List<Example>> loadStops(@Query("key") String key,
            @Query("query") String query);
            Retrofit retrofit = new Retrofit.Builder()
            .baseUrl("https://developer.cumtd.com/api/v2.2/json/")
            .addConverterFactory(GsonConverterFactory.create())
            .build();

    }


    import com.google.gson.annotations.Expose;
    import com.google.gson.annotations.SerializedName;

    public class Params {

        @SerializedName("count")
        @Expose
        private Integer count;
        @SerializedName("query")
        @Expose
        private String query;

        public Integer getCount() {
            return count;
        }

        public void setCount(Integer count) {
            this.count = count;
        }

        public String getQuery() {
            return query;
        }

        public void setQuery(String query) {
            this.query = query;
        }

    }


    import com.example.neelpatel.weatherapp.Params;
    import com.google.gson.annotations.Expose;
    import com.google.gson.annotations.SerializedName;

    public class Rqst {

        @SerializedName("method")
        @Expose
        private String method;
        @SerializedName("params")
        @Expose
        private Params params;

        public String getMethod() {
            return method;
        }

        public void setMethod(String method) {
            this.method = method;
        }

        public Params getParams() {
            return params;
        }

        public void setParams(Params params) {
            this.params = params;
        }

    }


    import com.google.gson.annotations.Expose;
    import com.google.gson.annotations.SerializedName;

    public class Status {

        @SerializedName("code")
        @Expose
        private Integer code;
        @SerializedName("msg")
        @Expose
        private String msg;

        public Integer getCode() {
            return code;
        }

        public void setCode(Integer code) {
            this.code = code;
        }

        public String getMsg() {
            return msg;
        }

        public void setMsg(String msg) {
            this.msg = msg;
        }

    }



    import java.util.List;

    import com.example.neelpatel.weatherapp.StopPoint;
    import com.google.gson.annotations.Expose;
    import com.google.gson.annotations.SerializedName;

    public class Stop {

        @SerializedName("stop_id")
        @Expose
        private String stopId;
        @SerializedName("stop_name")
        @Expose
        private String stopName;
        @SerializedName("code")
        @Expose
        private String code;
        @SerializedName("percent_match")
        @Expose
        private Integer percentMatch;
        @SerializedName("stop_points")
        @Expose
        private List<StopPoint> stopPoints = null;

        public String getStopId() {
            return stopId;
        }

        public void setStopId(String stopId) {
            this.stopId = stopId;
        }

        public String getStopName() {
            return stopName;
        }

        public void setStopName(String stopName) {
            this.stopName = stopName;
        }

        public String getCode() {
            return code;
        }

        public void setCode(String code) {
            this.code = code;
        }

        public Integer getPercentMatch() {
            return percentMatch;
        }

        public void setPercentMatch(Integer percentMatch) {
            this.percentMatch = percentMatch;
        }

        public List<StopPoint> getStopPoints() {
            return stopPoints;
        }

        public void setStopPoints(List<StopPoint> stopPoints) {
            this.stopPoints = stopPoints;
        }

    }


    import com.google.gson.annotations.Expose;
    import com.google.gson.annotations.SerializedName;

    public class StopPoint {

        @SerializedName("code")
        @Expose
        private String code;
        @SerializedName("stop_id")
        @Expose
        private String stopId;
        @SerializedName("stop_lat")
        @Expose
        private Double stopLat;
        @SerializedName("stop_lon")
        @Expose
        private Double stopLon;
        @SerializedName("stop_name")
        @Expose
        private String stopName;

        public String getCode() {
            return code;
        }

        public void setCode(String code) {
            this.code = code;
        }

        public String getStopId() {
            return stopId;
        }

        public void setStopId(String stopId) {
            this.stopId = stopId;
        }

        public Double getStopLat() {
            return stopLat;
        }

        public void setStopLat(Double stopLat) {
            this.stopLat = stopLat;
        }

        public Double getStopLon() {
            return stopLon;
        }

        public void setStopLon(Double stopLon) {
            this.stopLon = stopLon;
        }

        public String getStopName() {
            return stopName;
        }

        public void setStopName(String stopName) {
            this.stopName = stopName;
        }

    }

回答1:

You didn't provide much (any) information about the failure itself, but it's pretty easy to spot at least one possible bug. In the response you expect a list of Example objects:

Call<List<Example>> call = mtdApi.loadStops(key,s);

This is not good since you can cleary see in the documentation of GetStopsBySearch that the returned JSON object is not a list (i.e. not a JSON array). Fixing this is really easy, just expect a single Example object instead of a list of those:

Call<Example> call = mtdApi.loadStops(key,s);

This obviously means that you have to change the signature of the Callback but you don't need extra info for that.

来源：https://stackoverflow.com/questions/44864916/issues-with-get-request-using-retrofit-in-android-studio