如何发送请求标题是“内容类型”：“应用程序/ json”在排球时获取

Question

我尝试在Volley上使用GET，但我需要向application/json发送请求。

我看了一些答案，我尝试使用jsonBody ，但它显示错误：

null com.android.volley.ServerError

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);

    }


}

是否有人可以教我如何解决这个问题，任何帮助将不胜感激。

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

Answer 1

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

在你的实施

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);
    }
}

Answer 2

通常，要设置自定义标头，您需要覆盖getHeaders并手动设置自定义标头。 但是，volley以不同方式处理内容类型标题，并且getHeaders方式并不总是有效。

因此，对于您的情况，您需要覆盖getBodyContentType 。 所以你的代码看起来像

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);
        }


    }){
         @Override
         public String getBodyContentType(){
              return "application/json";
         }
    };

Answer 3

我尝试在Volley上使用GET

您调用的方法的文档说明了这一点

如果jsonRequest为null，则默认为GET的构造方法， 否则为POST

您无法使用HTTP JSON正文获取。 也许这就是错误。

 //I try to use this for send Header is application/json jsonBody = new JSONObject("{\\"type\\":\\"example\\"}"); 

这不是标题，所以在这里传入null来做GET

new JsonObjectRequest(url, null,

在请求结束时，重写一个方法来请求JSON

        ... 

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


    }) { // Notice no semi-colon here
        @Override 
        public Map<String, String> getHeaders() throws AuthFailureError { 
            Map<String, String> params = new HashMap<String, String>();                
            params.put("Content-Type", "application/json");
            return params; 
        } 
    };

Answer 4

像这样使用String请求而不是jsonrequest

            StringRequest loginMe = new StringRequest(Request.Method.GET, "http://114.35.246.42:2212/MobileApp/DEST_WebService.asmx/GetNews", new Response.Listener<String>() {

                @Override
                public void onResponse(String response) {

                    System.out.println("LoginActivity -- onResponse --> " + response);

                    if (progressDialog != null) {

                        progressDialog.dismiss();

                    }

                    try {

                        JSONObject jsonObject = new JSONObject(response);

                    } catch (Exception e) {

                        CommonUtility.somethingWentWrongDialog(activity,
                                "LoginActivity -- onResponse-- Exception --> ".concat(e.getMessage()));

                    }
                }
            }, new Response.ErrorListener() {

                @Override
                public void onErrorResponse(VolleyError error) {

                    if (progressDialog != null) {

                        progressDialog.dismiss();

                    }

                    CommonUtility.somethingWentWrongDialog(activity,
                            "LoginActivity -- onErrorResponse --> ".concat(error.getMessage()));

                }
            }) {

                @Override
                protected Map<String, String> getParams() {

                    Map<String, String> params = new HashMap<>();


                    System.out.println("LoginActivity -- LoginParams --> " + params.toString());

                    return params;

                }
            };

            loginMe.setRetryPolicy(new DefaultRetryPolicy(60000, DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
                    DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));

            Volley.newRequestQueue(activity).add(loginMe);