【发布时间】：2016-07-02 08:12:26
【问题描述】：
我正在开发 Retrofit 2.0（非常棒）来处理 API 响应。 当 API 成功回答时一切正常，我从 json 响应返回希望的转换对象
这里是请求示例：
ServiceAPI.getUser(new Callback<User>() {
@Override
public void onResponse(Call<User> call, Response<User> response) {
User user = response.body(); // user is my POJO
}
@Override
public void onFailure(Call<User> call, final Throwable t) {
Log.e(TAG, "Error: " + t.getMessage())
}
});
响应完成后，我返回 POJO（这是我的主要目的），而不是要解析的 json，以避免样板。
所以这里是我的代码来处理这个：
// the interface to handle calls
protected interface ServiceAPI {
@GET("/user/{userId}")
Call<User> getUser(@Path("userId") String userId);
}
// the GSON part for converting data
Gson gson = new GsonBuilder()
.registerTypeAdapterFactory(new ItemTypeAdapterFactory())
.setDateFormat("yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'SSS'Z'")
.create();
// an interceptor to log requests responses
OkHttpClient okClient = new OkHttpClient.Builder()
.addInterceptor(new LogJsonInterceptor())
.build();
// the retrofit builder
retrofit = new Retrofit.Builder()
.baseUrl(mBaseUrl)
.client(okClient)
.addConverterFactory(GsonConverterFactory.create(gson))
.build();
// the interceptor to log requests
public static class LogJsonInterceptor implements Interceptor {
@Override
public okhttp3.Response intercept(Interceptor.Chain chain) throws IOException {
Request request = chain.request();
okhttp3.Response response = chain.proceed(request);
String rawJson = response.body().string();
Log.d(TAG, rawJson);
// Re-create the response before returning it because body can be read only once
return response.newBuilder().body(ResponseBody.create(response.body().contentType(), rawJson)).build();
}
}
// here the magic to handle json response and get data from "data" json key
public static class ItemTypeAdapterFactory implements TypeAdapterFactory {
public <T> TypeAdapter<T> create(Gson gson, final TypeToken<T> type) {
final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);
final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
return new TypeAdapter<T>() {
public void write(JsonWriter out, T value) throws IOException {
delegate.write(out, value);
}
private RestError error;
public T read(JsonReader in) throws IOException {
JsonElement jsonElement = elementAdapter.read(in);
if (jsonElement.isJsonObject()) {
JsonObject jsonObject = jsonElement.getAsJsonObject();
if (jsonObject.has("data")) {
jsonElement = jsonObject.get("data");
}
}
return delegate.fromJsonTree(jsonElement);
}
}.nullSafe();
}
}
// here the method to call from an activity for example to get an User
public static void getUser(final String userId, final Callback<User> callback) {
serviceAPI.getUser(userId).enqueue(new Callback<User>() {
@Override
public void onResponse(Call<User> call, Response<User> response) {
callback.onResponse(call, response);
}
@Override
public void onFailure(Call<User> call, Throwable t) {
callback.onFailure(call, t);
}
});
}
// here the call from the Activity
ServiceAPI.getUser(new Callback<User>() {
@Override
public void onResponse(Call<User> call, Response<User> response) {
User user = response.body();
}
@Override
public void onFailure(Call<User> call, final Throwable t) {
Log.e(TAG, "Error: " + t.getMessage())
}
});
// when API answers with success (code 200 from headers)
{
"data":
{
"id":1,
"name":"myname",
"email":"myemail"
}
}
所以这里一切正常，因为我从“数据”得到响应并将响应转换为我的 POJO
问题： 但是当 API 回答错误时（也有来自标头的代码 200），我得到了这个：
{
"error":
{
"code":200
"type":"OAuth_exception",
"message":"You need an access token to get an user",
}
}
问题是改造“响应”仍然成功并且errorBody为空
所以在这里，我会将其转换为 RestError POJO（如下）并在调用 getUser 方法时将其发送到调用中
public class RestError {
private int code;
private String message;
private String type;
public RestError(int code, String message, String type) {
this.code = code;
this.message = message;
this.type = type;
}
}
有办法解决这个问题吗？
更新：
我在 ItemTypeAdatperFactory 中添加了这个
public T read(JsonReader in) throws IOException {
JsonElement jsonElement = elementAdapter.read(in);
if (jsonElement.isJsonObject()) {
JsonObject jsonObject = jsonElement.getAsJsonObject();
if (jsonObject.has("data")) {
jsonElement = jsonObject.get("data");
} else if (jsonObject.has("error")) {
jsonElement = jsonObject.get("error");
TypeAdapter<RestError> restErrorTypeAdapter = gson.getAdapter(RestError.class);
RestError error = restErrorTypeAdapter.fromJsonTree(jsonElement);
return (T) error;
}
}
return delegate.fromJsonTree(jsonElement);
}
我创建了一个这样的自定义回调：
public abstract static class CustomCallback<T> implements Callback<T> {
public abstract void onError(RestError error);
public abstract void onSuccess(T body);
@Override
public void onResponse(Call<T> call, Response<T> response) {
if(response.body() instanceof RestError) {
onError((RestError) response.body());
} else {
onSuccess(response.body());
}
}
@Override
public void onFailure(Call<T> call, Throwable t) {
Log.e(TAG, t.toString());
}
}
那么现在调用是怎样的：
ServiceAPI.getUser(new ServiceAPI.CustomCallback<User>() {
@Override
public void onError(RestError error) {
Log.e(TAG, error.toString());
}
@Override
public void onSuccess(User body) {
Log.d(TAG, body.toString());
User user = body;
}
@Override
public void onFailure(Call<User> call, Throwable t) {
Log.e(TAG, t.toString());
}
});
所以现在当发生错误时，我从 onError() 中获取它，否则 onSuccess() 并且似乎可以完成这项工作
你怎么看？
【问题讨论】：
-
我实际上遇到了同样的问题，如果它是 200，我能够获得响应。但我想要的是从 202 获取东西。所以对于 200 响应，我们已经创建了一个 SuccessResponse GSON 类。对于 202 类，我还创建了另一个依赖于 JSON 响应的类。我无法同时使用两者。我也尝试过扩展。但它们都不起作用。请问有什么建议吗？