如何从抽射功能onResponse返回值？ [英] How can I return value from function onResponse of Volley?

问题描述

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;
}}

我想打造的getString的对象，并调用get_String其他领域。但似乎很难从onResponse得到的结果出来。我知道它不能在当前的方式工作。谁能帮我解决这个问题呢？

I would to build an object of getString and call get_String in other fields. But it seems that it is hard to get the result out from the onResponse. I know it cannot work in this current way. Could anyone help me to settle this problem?

推荐答案

您想要使用的回调接口，像这样：

You want to use callback interfaces like so:

public String get_String(VolleyCallback callback) {
    StringRequest strReq = new StringRequest(Request.Method.GET, url, new     Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            result=response;
            callback.onSuccess(result);
        }
    }...
}}

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

内活动实例code：

Example code inside activity:

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

您还可以VolleyCallback更强劲，使用泛型类型，如果你想要做的处理，或添加的start（），失败（例外五），完成（）等方法，以做一些更细致的状态检查。

You can also make VolleyCallback more robust, using generic types if you want to do processing, or adding start(), failed(Exception e), complete(), etc methods to do a little more fine-grained state checking.

请记住，这是一个异步调用，所以你将有更新的观点，等等，当你得到的结果回来（成功（）内）。

Keep in mind this is an async call, so you will have to update views, etc when you get the result back (inside success()).

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