java - 在Volley上进行GET时，如何发送请求 header 为 "Content-Type":"application/json"

我尝试在Volley上使用GET，但是我需要将请求发送到application/json。

我看一些答案，尝试使用jsonBody，但显示错误:



这是我的代码:

public class MainActivity extends AppCompatActivity {

    String url = "http://114.35.246.42:2212/MobileApp/DEST_WebService.asmx/GetNews";
    JSONObject jsonBody;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        try {
            //I try to use this for send Header is application/json
            jsonBody = new JSONObject("{\"type\":\"example\"}");
        } catch (JSONException ex) {
            ex.printStackTrace();
        }

        RequestQueue mQueue = Volley.newRequestQueue(getApplicationContext());

        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(url, jsonBody,
                new Response.Listener<JSONObject>() {


                    @Override
                    public void onResponse(JSONObject response) {
                        Log.d("TAG", response.toString());
                    }
                }, new Response.ErrorListener() {

            @Override
            public void onErrorResponse(VolleyError error) {
                Log.e("TAG", error.getMessage(), error);
            }


        });


        mQueue.add(jsonObjectRequest);

    }


}

有谁能教我如何解决这个问题，对您的帮助将不胜感激。

这是我的网址:String url = "http://114.35.246.42:2212/MobileApp/DEST_WebService.asmx/GetNews";

最佳答案

@Override
public Map<String, String> getHeaders() throws AuthFailureError {
    Map<String, String> params = new HashMap<String, String>();
    params.put("Content-Type", "application/json");
    return params;
}

在您的实现

public class MainActivity extends AppCompatActivity {

    String url = "http://114.35.246.42:2212/MobileApp/DEST_WebService.asmx/GetNews";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        RequestQueue mQueue = Volley.newRequestQueue(getApplicationContext());

        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(url, jsonBody,
            new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    Log.d("TAG", response.toString());
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.e("TAG", error.getMessage(), error);
                }
            }) { //no semicolon or coma
            @Override
            public Map<String, String> getHeaders() throws AuthFailureError {
                Map<String, String> params = new HashMap<String, String>();
                params.put("Content-Type", "application/json");
                return params;
            }
        };
        mQueue.add(jsonObjectRequest);
    }
}