我正在尝试在 java (android) 中调用 web api（我在 ASP.NET 中创建的）

Question

This is my code:

import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;

import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.Response;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.Locale;

public class MainActivity extends AppCompatActivity {
String url="10.152.2.45";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
private class ListarEventos extends AsyncTask<String, Void, ArrayList<Evento>> {
    private OkHttpClient client = new OkHttpClient();
    @Override
    protected void onPostExecute(ArrayList<Evento> direcciones) {
        super.onPostExecute(direcciones);
    }
    @Override
    protected ArrayList<Evento> doInBackground(String... params) {
    Request request = new Request.Builder()
            .url(url)
            .build();
    try {
        Response response = client.newCall(request).execute();
        return parseResult(response.body().string());     

    } catch (IOException | JSONException e) {
        Log.d("Error",e.getMessage());
        return new ArrayList<Evento>();
    }
}
ArrayList<Evento> parseResult(String JSONstr) throws JSONException {
    ArrayList<Evento> eventos = new ArrayList<>();
    JSONObject json = new JSONObject(JSONstr);                
    JSONArray jsonEventos = json.getJSONArray("results");
    Date result=new Date ();
    for (int i=0; i<jsonEventos.length(); i++) {
        JSONObject jsonResultado = jsonEventos.getJSONObject(i);
        int jsonId = jsonResultado.getInt("Id");
        String jsonMat = jsonResultado.getString("Materia");
        String jsonTipo = jsonResultado.getString("Tipo");
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH");
        String Fecha=jsonResultado.getString("Fecha");
        try {
            result = df.parse(Fecha);
        }catch (Exception e) {

        }
        String jsonDesc = jsonResultado.getString("Descripcion");
        Evento d = new Evento();
        d.Id=jsonId;
        d.Materia=jsonMat;
        d.Tipo=jsonTipo;
        d.Fecha=result;
        d.Descripcion=jsonDesc;
        eventos.add(d); 
    }
    return eventos;
}

}
}

First of all, i don't know how to call the service, if I write the IP adress it doesn't work because I debug the android while I debug the API (in the same computer). What the code is supposed to do is to call the API, go to localhost/api/Eventos/Get and get a json with all the events.

PS: I wrote the computer IP because if I write localhost it doesn't work

Answer 1

To call the web API running on your machine you need to know it's exact url - just localhost or your IP is not enough, you should specify the port it is running on and it's endpoint, for example localhost:8080/myapi

Also, you should know what kind of request that API expects - does it expect a GET, POST, some other type of request? What parameters do you need to pass?

As you have the web service launched locally, you should be able to find out this information about the service. Also, there's no difference for the caller (in this case your Android app) in which language web service is developed - it could be written in any other language than ASP.NET and behave the same.