Question

public class getString  {
String tag_string_req = "string_raq";
String url = "http://10.0.2.2/eat/locations/index.json";
String result="";

public String get_String() {
    StringRequest strReq = new StringRequest(Request.Method.GET, url, new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            result=response;
            System.out.println(response);
            ;

        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError volleyError) {
            System.out.println(volleyError.getMessage());
        }
    });
    AppController.getInstance().addToRequestQueue(strReq, tag_string_req);
    return result;
}}

我想构建一个getString对象并在其他字段中调用get_String。但似乎很难从onResponse中得到结果。我知道它不能以当前的方式工作。谁能帮我解决这个问题？

Answer 1

您希望使用如下的回调接口：

public void getString(final VolleyCallback callback) {
    StringRequest strReq = new StringRequest(Request.Method.GET, url, new     Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            ...  // (optionally) some manipulation of the response 
            callback.onSuccess(response);
        }
    }...
}}

将回调定义为

public interface VolleyCallback{
    void onSuccess(String result);
}

活动内的示例代码：

public void onResume(){
    super.onResume();

    getString(new VolleyCallback(){
         @Override
         public void onSuccess(String result){
             ... //do stuff here
         }
    });
}

如果您想要进行处理，或者添加VolleyCallback，start()，failed(Exception e)等方法，您还可以使complete()更强大，使用通用类型更精细的状态检查。

请记住，这是一次异步调用，因此当您获得结果时（在success()内），您必须更新视图等。

Answer 2

override fun onCreateView(
    inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {


    val rootView = inflater.inflate(R.layout.mission_fragment_list, container, false)
    val recycler = rootView.findViewById(R.id.list) as RecyclerView

    GlobalScope.async {
        val queue = Volley.newRequestQueue(context)
        val gson = Gson()

        val url = "YPUR_API"
        val stringRequest = StringRequest(
            Request.Method.GET, url,
            Response.Listener<String> { response ->

                recycler.layoutManager = LinearLayoutManager(context)
                val listType: Type = object : TypeToken<MutableList<MissionModel>?>() {}.type
                val data: MutableList<MissionModel> = gson.fromJson(response, listType)
                recycler.adapter = MissionAdapter(data)
            },
            Response.ErrorListener { error ->
                error.printStackTrace()
            })

        queue.add(stringRequest)


    }
    return rootView

}

简单代码。您需要添加依赖项实现'org.jetbrains.kotlinx：kotlinx-coroutines-android：1.1.1'

如何从Volley的响应中返回值？

2 个答案: