android - error.networkResponse 为空时 Android Volley 中的 Http 状态代码

Question

我在 Android 平台上使用 Google Volley。我遇到问题，其中 onErrorResponse 中的 error 参数返回 null networkResponse对于我正在使用的 RESTful API，我需要确定通常以 401 (SC_UNAUTHORIZED) 或 500 (SC_INTERNAL_SERVER_ERROR) 到达的 Http 状态代码，我偶尔可以通过以下方式检查:

final int httpStatusCode = error.networkResponse.statusCode;
if(networkResponse == HttpStatus.SC_UNAUTHORIZED) {
    // Http status code 401: Unauthorized.
}

这会引发 NullPointerException，因为 networkResponse 为空。

如何确定函数onErrorResponse中的Http状态码？

或者，如何确保 error.networkResponse 在 onErrorResponse 中不为空？

Answer 1

Or, how can I ensure error.networkResponse is non-null in onErrorResponse?

我的第一个想法是检查对象是否为空。

@Override
public void onErrorResponse(VolleyError error) {
    NetworkResponse networkResponse = error.networkResponse;
    if (networkResponse != null && networkResponse.statusCode == HttpStatus.SC_UNAUTHORIZED) {
        // HTTP Status Code: 401 Unauthorized
    }
}

或者，您也可以尝试通过扩展 Request 来获取状态码类和覆盖 parseNetworkResponse .

例如，如果扩展摘要 Request<T>类

public class GsonRequest<T> extends Request<T> {

    ...
    private int mStatusCode;

    public int getStatusCode() {
        return mStatusCode;
    }
    ...

    @Override
    protected Response<T> parseNetworkResponse(NetworkResponse response) {

        mStatusCode = response.statusCode;
        try {
            Log.d(TAG, "[raw json]: " + (new String(response.data)));
            Gson gson = new Gson();
            String json = new String(response.data, HttpHeaderParser.parseCharset(response.headers));
            return Response.success(gson.fromJson(json, mClazz),
                HttpHeaderParser.parseCacheHeaders(response));

        } catch (UnsupportedEncodingException e) {
            return Response.error(new ParseError(e));
        } catch (JsonSyntaxException e) {
            return Response.error(new ParseError(e));
        }
    }
    ...
}

或者，如果您正在使用已经扩展了抽象 Request<T> 的工具箱类之一类，你不想混淆 parseNetworkResponse(NetworkResponse networkResponse) 的实现, 继续覆盖该方法但通过 super.parseNetworkResponse(networkResponse) 返回 super 的实现

例如StringResponse

public class MyStringRequest extends StringRequest {

    private int mStatusCode;

    public MyStringRequest(int method, String url, Listener<String> listener,
            ErrorListener errorListener) {
        super(method, url, listener, errorListener);
    }

    public int getStatusCode() {
        return mStatusCode;
    }

    @Override
    protected Response<String> parseNetworkResponse(NetworkResponse response) {
        mStatusCode = response.statusCode;
        return super.parseNetworkResponse(response);
    }
}

用法:

public class myClazz extends FragmentActivity {


    private Request mMyRequest;
    ...

    public void makeNetworkCall() {
    mMyRequest = new MyNetworkRequest(
            Method.GET, 
            BASE_URL + Endpoint.USER,
            new Listener<String>() {

                @Override
                public void onResponse(String response) {
                    // Success

                }
            }, 
            new ErrorListener() {

                @Override
                public void onErrorResponse(VolleyError error) {
                    if (mMyRequest.getStatusCode() == 401) {
                        // HTTP Status Code: 401 Unauthorized
                    }
                }
            });

    MyVolley.getRequestQueue().add(request);
}

当然，覆盖内联方法的选项也是可用的

public class MyClazz extends FragmentActivity {

    private int mStatusCode;

    ...

    public void makeNetworkCall() {

        StringRequest request = new StringRequest(
                Method.GET, 
                BASE_URL + Endpoint.USER,
                new Listener<String>() {

                    @Override
                    public void onResponse(String response) {
                        // Success

                    }
                }, 
                new ErrorListener() {

                    @Override
                    public void onErrorResponse(VolleyError error) {
                        if (mStatusCode == 401) {
                            // HTTP Status Code: 401 Unauthorized
                        }
                    }
                }) {

                    @Override
                    protected Response<String> parseNetworkResponse(NetworkResponse response) {
                        mStatusCode = response.statusCode;
                        return super.parseNetworkResponse(response);
                    }
                };
    MyVolley.getRequestQueue.add(request);
}

更新:
HttpStatus已弃用。使用HttpURLConnection反而。见 Link .