改造异步请求是使用2个方法onResponse（）和onFailure（）进行回调。
我不想总是覆盖这2个方法并处理错误情况。
因此，当我想通过google的ApiResponse的GithubBrowserSample封装改造响应主体并转换错误时，如下所示：
public class ApiResponse<T> {
public final int code;
@Nullable
public final T body;
@Nullable
public final String errorMessage;
public ApiResponse(Throwable error) {
code = -1;
body = null;
if (error instanceof IOException) {
errorMessage = "No network error";
}
else {
errorMessage = error.getMessage();
}
}
public ApiResponse(Response<T> response) {
code = response.code();
if (response.isSuccessful()) {
body = response.body();
errorMessage = null;
}
else {
String message = null;
if (response.errorBody() != null) {
try {
message = response.errorBody().string();
} catch (IOException e) {
e.printStackTrace();
}
}
if (message == null || message.trim().length() == 0) {
message = response.message();
}
errorMessage = message;
body = null;
}
}
public boolean isSuccessful() {
return code >= 200 && code < 300;
}
}
我也想使用Gson转换器来转换改造响应，然后将其与ApiResponse打包在一起。
如果我使用像
Call<ApiResponse<Result>> requestCall = webClient.request1(xxx,xxx);
requestCall.enqueue(new Callback<ApiResponse<Result>> {});
看来行不通。 json响应数据无法解析为Result对象。
因此，我考虑编写引用retrofit sample的自定义呼叫适配器以替换为Retrofit Call。但是我在转换泛型类型时仍然有问题。
public class MyCallAdapterFactory extends CallAdapter.Factory {
@Nullable
@Override
public CallAdapter<?, ?> get(Type returnType, Annotation[] annotations, Retrofit retrofit) {
if (getRawType(returnType) != MyCall.class) {
return null;
}
Type observableType = getParameterUpperBound(0, (ParameterizedType) returnType);
Class<?> rawObservableType = getRawType(observableType);
if (rawObservableType != ApiResponse.class) {
throw new IllegalArgumentException("type must be a resource");
}
if (! (observableType instanceof ParameterizedType)) {
throw new IllegalArgumentException("resource must be parameterized");
}
Type bodyType = getParameterUpperBound(0, (ParameterizedType) observableType);
Executor executor = retrofit.callbackExecutor();
return new MyCallAdapter<>(bodyType, executor);
}
}
public class MyCallAdapter<T> implements CallAdapter<T, MyCall<T>> {
private final Type responseType;
private final Executor callbackExecutor;
public MyCallAdapter(Type responseType, Executor callbackExecutor) {
this.responseType = responseType;
this.callbackExecutor = callbackExecutor;
}
@Override
public Type responseType() {
return null;
}
@Override
public MyCall<T> adapt(Call<T> call) {
return new MyCallImpl<>(call, callbackExecutor);
}
}
public class MyCallImpl<T> implements MyCall<T> {
private final Call<T> call;
private final Executor callbackExecutor;
MyCallImpl(Call<T> call, Executor callbackExecutor) {
this.call = call;
this.callbackExecutor = callbackExecutor;
}
@Override
public void enqueue(MyCallback<T> callback) {
call.enqueue(new Callback<T>() {
@Override
public void onResponse(Call<T> call, Response<T> response) {
/* This is the problem. it will seems wrap to ApiResponse<ApiResponse<Result>>> because T is <ApiResponse<Result>>.
*/
callback.onResult(new ApiResponse<>(response));
}
@Override
public void onFailure(Call<T> call, Throwable t) {
/** This one is also the issue. */
callback.onResult(new ApiResponse<>(t));
}
});
}
@Override
public void cancel() {
call.cancel();
}
@Override
public MyCall<T> clone() {
return new MyCallImpl<>(call.clone(), callbackExecutor);
}
}
public interface MyCallback<T> {
void onResult(ApiResponse<T> response);
}
上面的代码在处理双参数化泛型类型时存在问题。我不知道该如何处理。
同时运行此代码也会崩溃
Caused by: java.lang.NullPointerException: type == null
at retrofit2.Utils.checkNotNull(Utils.java:286)
at retrofit2.Retrofit.nextResponseBodyConverter(Retrofit.java:324)
at retrofit2.Retrofit.responseBodyConverter(Retrofit.java:313)
at retrofit2.ServiceMethod$Builder.createResponseConverter(ServiceMethod.java:736)
at retrofit2.ServiceMethod$Builder.build(ServiceMethod.java:169)
有人可以帮助如何让
MyCall<ApiResponse<Result>>用MyCallback<ApiResponse<Result>>呼叫入队吗？结果是使用Gson转换器解析json数据内容。public class MyCallAdapter<T> implements CallAdapter<T, MyCall<ApiResponse<T>>> {
public MyCall<ApiResponse<T>> adapt(Call<T> call) {
/* This one will have the problem after changing MyCall<T> to MyCall<ApiResponse<T>>, Parameterized type mismatch.*/
return new MyCallImpl<>(call, callbackExecutor);
}
}
有人可以帮我指出这个问题吗？
最佳答案
修改MyCallAdapter，MyCallback和MyCallImpl。 @Rahul指出了响应类型，现在一切正常。
public class MyCallAdapter<T> implements CallAdapter<T, MyCall<ApiResponse<T>>> {
private final Type responseType;
private final Executor callbackExecutor;
public MyCallAdapter(Type responseType, Executor callbackExecutor) {
this.responseType = responseType;
this.callbackExecutor = callbackExecutor;
}
@Override
public Type responseType() {
return responseType;
}
@Override
public MyCall<ApiResponse<T>> adapt(Call<T> call) {
return new MyCallImpl<>(call, callbackExecutor);
}
}
public interface MyCallback<T> {
void onResult(T response);
}
public class MyCallImpl<T> implements MyCall<ApiResponse<T>> {
private final Call<T> call;
private final Executor callbackExecutor;
MyCallImpl(Call<T> call, Executor callbackExecutor) {
this.call = call;
this.callbackExecutor = callbackExecutor;
}
@Override
public void enqueue(MyCallback<ApiResponse<T>> callback) {
call.enqueue(new Callback<T>() {
@Override
public void onResponse(Call<T> call, Response<T> response) {
callback.onResult(new ApiResponse<>(response));
}
@Override
public void onFailure(Call<T> call, Throwable t) {
callback.onResult(new ApiResponse<>(t));
}
});
}
@Override
public void cancel() {
call.cancel();
}
@Override
public MyCall<ApiResponse<T>> clone() {
return new MyCallImpl<>(call.clone(), callbackExecutor);
}
}
以上是正确的实现。是的