android - 主线程上的 Okhttp 响应回调

Question

我创建了一个帮助类来处理我的应用程序中的所有 http 调用。它是一个简单的 okhttp 单例包装器，看起来像这样(我省略了一些不重要的部分):

public class HttpUtil {

    private OkHttpClient client;
    private Request.Builder builder;

    ...

    public void get(String url, HttpCallback cb) {
        call("GET", url, cb);
    }

    public void post(String url, HttpCallback cb) {
        call("POST", url, cb);
    }

    private void call(String method, String url, final HttpCallback cb) {
        Request request = builder.url(url).method(method, method.equals("GET") ? null : new RequestBody() {
            // don't care much about request body
            @Override
            public MediaType contentType() {
                return null;
            }

            @Override
            public void writeTo(BufferedSink sink) throws IOException {

            }
        }).build();

        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Request request, Throwable throwable) {
                cb.onFailure(null, throwable);
            }

            @Override
            public void onResponse(Response response) throws IOException {
                if (!response.isSuccessful()) {
                    cb.onFailure(response, null);
                    return;
                }
                cb.onSuccess(response);
            }
        });
    }


    public interface HttpCallback  {

        /**
         * called when the server response was not 2xx or when an exception was thrown in the process
         * @param response - in case of server error (4xx, 5xx) this contains the server response
         *                 in case of IO exception this is null
         * @param throwable - contains the exception. in case of server error (4xx, 5xx) this is null
         */
        public void onFailure(Response response, Throwable throwable);

        /**
         * contains the server response
         * @param response
         */
        public void onSuccess(Response response);
    }

}

然后，在我的主要 Activity 中，我使用这个助手类:

HttpUtil.get(url, new HttpUtil.HttpCallback() {
            @Override
            public void onFailure(Response response, Throwable throwable) {
                // handle failure
            }

            @Override
            public void onSuccess(Response response) {
                // <-------- Do some view manipulation here
            }
        });

onSuccess 在代码运行时抛出异常:

android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.

据我了解，Okhttp 回调在主线程上运行，为什么会出现此错误？

** 顺便说一句，我创建了 HttpCallback 接口(interface)来包装 Okhttp 的 Callback 类，因为我想改变 onResponse 的行为> 和 onFailure 这样我就可以统一处理由于 i/o 异常导致的失败响应和由于服务器问题导致的失败响应的逻辑。

谢谢。

Answer 1

From my understanding, Okhttp callbacks run on the main thread so why do I get this error ?

这不是真的。回调在后台线程上运行。如果您想立即处理 UI 中的某些内容，则需要发布到主线程。

由于您已经有一个围绕回调的包装器，您可以在帮助器内部执行此操作，以便为方便起见在主线程上调用所有 HttpCallback 方法。