我正在使用Retrofit 2,我在这一行得到一个空指针异常：
RetrofitClient.APIError error = RetrofitClient.ErrorUtils.parseError(response,retrofit);
错误为空.更多细节：
这是API返回错误的格式：
{
"error": {
"message": "Incorrect credentials","statusCode": 401
}
}
new Callback<LoginResponse>() {
@Override
public void onResponse(Response<LoginResponse> response,Retrofit retrofit) {
if (listener != null) {
if (response.isSuccess() && response.body() != null) {
User user = RetrofitUserToUserMapper.fromRetrofitUser(response.body().getLoginUser());
} else {
RetrofitClient.APIError error = RetrofitClient.ErrorUtils.parseError(response,retrofit);
listener.onUserLoginFailure(error.getErrorMessage()); // NPE - error is null
}
}
}
@Override
public void onFailure(Throwable t) {
if (listener != null) {
listener.onUserLoginFailure("");
}
}
}
这是我的Retrofit 2课程：
public class RetrofitClient {
public static final String API_ROOT = "http://example.com/api/v1/";
private static final String HEADER_OS_VERSION = "X-OS-Type";
private static final String HEADER_APP_VERSION = "X-App-Version";
private static final String HEADER_OS_VERSION_VALUE_ANDROID = "android";
private RetrofitClient() {
}
private static Retrofit INSTANCE;
public static Retrofit getInstance() {
if (INSTANCE == null) {
setupRestClient();
}
return INSTANCE;
}
public static void setupRestClient() {
OkHttpClient httpClient = new OkHttpClient();
addHeadersrequiredForAllRequests(httpClient,BuildConfig.VERSION_NAME);
INSTANCE = new Retrofit.Builder()
.baseUrl(API_ROOT)
.addConverterFactory(GsonConverterFactory.create())
.client(httpClient)
.build();
}
private static void addHeadersrequiredForAllRequests(OkHttpClient httpClient,final String appVersion) {
class RequestInterceptor implements Interceptor {
@Override
public com.squareup.okhttp.Response intercept(Chain chain) throws IOException {
Request request = chain.request().newBuilder()
.addHeader(HEADER_OS_VERSION,HEADER_OS_VERSION_VALUE_ANDROID)
.addHeader(HEADER_APP_VERSION,appVersion)
.build();
return chain.proceed(request);
}
}
httpClient.networkInterceptors().add(new RequestInterceptor());
}
public static class ErrorUtils {
public static APIError parseError(Response<?> response,Retrofit retrofit) {
Converter<ResponseBody,APIError> converter =
retrofit.responseConverter(APIError.class,new Annotation[0]);
APIError error;
try {
error = converter.convert(response.errorBody());
} catch (IOException e) {
e.printStackTrace();
return new APIError();
} catch (Exception e) {
e.printStackTrace();
return new APIError();
}
return error;
}
}
public static class APIError {
@SerializedName("error")
public
ErrorResponse loginError;
public ErrorResponse getLoginError() {
return loginError;
}
public String getErrorMessage() {
return loginError.message;
}
private class ErrorResponse {
@SerializedName("message")
private String message;
@SerializedName("statusCode")
public int statusCode;
public String getMessage() {
return message;
}
public int getStatusCode() {
return statusCode;
}
@Override
public String toString() {
return "LoginErrorResponseBody{" +
"message='" + getMessage() + '\'' +
",statusCode=" + statusCode +
'}';
}
public void setMessage(String message) {
this.message = message;
}
}
}
}
我从本教程获得了错误utils类,但稍微改了一下因为它们的示例中的错误格式不同：
编辑：这是Converter类：
/**
* Convert objects to and from their representation as HTTP bodies. Register a converter with
* Retrofit using {@link Retrofit.Builder#addConverterFactory(Factory)}.
*/
public interface Converter<F,T> {
T convert(F value) throws IOException;
abstract class Factory {
/**
* Create a {@link Converter} for converting an HTTP response body to {@code type} or null if it
* cannot be handled by this factory.
*/
public Converter<ResponseBody,?> fromResponseBody(Type type,Annotation[] annotations) {
return null;
}
/**
* Create a {@link Converter} for converting {@code type} to an HTTP request body or null if it
* cannot be handled by this factory.
*/
public Converter<?,RequestBody> toRequestBody(Type type,Annotation[] annotations) {
return null;
}
}
}
解决方法
更新：
如果要在下面使用自定义类而不是JSONObject,可以参考以下内容：
自定义类：
public class ResponseError {
Error error;
class Error {
int statusCode;
String message;
}
}
@GET("/api/geterror")
Call<ResponseError> getError2();
然后,在MainActivity.java中：
Call<ResponseError> responseErrorCall = service.getError2();
responseErrorCall.enqueue(new Callback<ResponseError>() {
@Override
public void onResponse(Response<ResponseError> response,Retrofit retrofit) {
if (response.isSuccess() && response.body() != null){
Log.i(LOG_TAG,response.body().toString());
} else {
if (response.errorBody() != null){
RetrofitClient.APIError error = RetrofitClient.ErrorUtils.parseError(response,retrofit);
Log.e(LOG_TAG,error.getErrorMessage());
}
}
}
@Override
public void onFailure(Throwable t) {
Log.e(LOG_TAG,t.toString());
}
});
我刚用我的Web服务测试了你的RetrofitClient类.我对你的APIError类做了一个小的更新,如下所示(添加2个构造函数,实际上它们没有被调用)：
public APIError(){
this.loginError = new ErrorResponse();
}
public APIError(int statusCode,String message) {
this.loginError = new ErrorResponse();
this.loginError.statusCode = statusCode;
this.loginError.message = message;
}
接口：
public interface WebAPIService {
@GET("/api/geterror")
Call<JSONObject> getError();
}
主要活动：
// Retrofit 2.0-beta2
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(API_URL_BASE)
.addConverterFactory(GsonConverterFactory.create())
.build();
WebAPIService service = retrofit.create(WebAPIService.class);
Call<JSONObject> jsonObjectCall = service.getError();
jsonObjectCall.enqueue(new Callback<JSONObject>() {
@Override
public void onResponse(Response<JSONObject> response,t.toString());
}
});
我的Web服务(Asp.Net Web API)：
根据您的JSON响应数据,我使用了以下代码：
[Route("api/geterror")]
public HttpResponseMessage GetError()
{
var detailError = new
{
message = "Incorrect credentials",statusCode = 401
};
var myError = new
{
error = detailError
};
return Request.CreateResponse(HttpStatusCode.Unauthorized,myError);
}
它的工作原理！希望能帮助到你！
