Android Volley Request 完全失败

Question

I am trying to get data from an Http request to my own API. Running the request in my browser (swapping the IP with localhost) gets me:

["Herbalism","Mining","Skinning","Alchemy","Blacksmithing","Enchanting","Engineering","Inscription","Jewelcrafting","Leatherworking","Tailoring","Archaeology","Cooking","Fishing"]

I am using the following code, modified from the example provided here: https://www.tutorialspoint.com/how-to-use-volley-library-to-parse-json-in-android-kotlin-app It does not print my "Print anything at all". From what I can tell this does nothing. I have tried many different things including suggestions from here: Can I do a synchronous request with volley? and here: Volley Timeout Error and feel that I am in no way closer to getting this request to work. The firewall permits this traffic. The catch JSONException and Response.ErrorListener are also not putting anything out. I am using plain http, no certs or anything. Ultimately I want to populate a Spinner with this data but for now I can't even get this most basic implementation to work.

package com.wowahapp

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.*
import androidx.recyclerview.widget.RecyclerView
import com.android.volley.Request
import com.android.volley.RequestQueue
import com.android.volley.Response
import com.android.volley.toolbox.*
import org.json.JSONException


class AddRecipeActivity : AppCompatActivity() {

    lateinit var searchTextView : TextView
    private var requestQueue : RequestQueue? = null


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_add_recipe)


        searchTextView = findViewById<TextView>(R.id.searchTextView) as TextView

        getAllProfessions(searchTextView)

    }

    fun getAllProfessions(searchText : TextView) {

        val url = "http://192.168.0.24:49155/allprofessions"
        val request = JsonObjectRequest(Request.Method.GET, url, null, Response.Listener {
                response ->try {
            val jsonArray = response.getJSONArray("name")
            println("Print anything at all!")
            for (i in 0 until jsonArray.length()) {
                println(jsonArray.getJSONObject(i))
            }
        } catch (e: JSONException) {
            e.printStackTrace()
        }
        }, Response.ErrorListener { error -> error.printStackTrace() })
        requestQueue?.add(request)
    }
}

Answer 1

This document explain the implementation of a VolleyWebService class: http://code.sunnyjohn.in/index.php/2020/12/24/retrieve-data-volley/

You have to instantiate the class, create a new request queue and then add to the request queue.

Answer 2

First create custom VolleyWebService class as follows:

class VolleyWebService constructor(context: Context) {
    private var INSTANCE: VolleyWebService? = null
           companion object {
            @Volatile
            private var INSTANCE: VolleyWebService? = null
            fun getInstance(context: Context) =
                INSTANCE ?: synchronized(this) {
                    INSTANCE ?: VolleyWebService(context).also {
                        INSTANCE = it
                    }
                }
        }
    
    val requestQueue: RequestQueue by lazy {
                Volley.newRequestQueue(context.applicationContext)
    }

    fun <T> addToRequestQueue(req: Request<T>) {
        requestQueue.add(req)
    }
}

Then modify your function getAllProfessions like this:

fun getAllProfessions(searchText : TextView) {

        val url = "http://192.168.0.24:49155/allprofessions"
        val request = JsonObjectRequest(Request.Method.GET, url, null, Response.Listener {
                response ->try {
            val jsonArray = response.getJSONArray("name")
            println("Print anything at all!")
            for (i in 0 until jsonArray.length()) {
                println(jsonArray.getJSONObject(i))
            }
        } catch (e: JSONException) {
            e.printStackTrace()
        }
        }, Response.ErrorListener { error -> error.printStackTrace() })
//changes made here
      VolleyWebService.getInstance(context).addToRequestQueue(request)  
    }
}