Question

我使用带有异步回调的okhttp3从服务器获取JSONArrays / JSONObjects然后解析它们并创建传递给回调函数的特定对象。对于每种方法，大多数回调代码都是相同的，但有些代码行不同。是否有一种模式可用于减少代码行，以便我不必为不同的对象反复编写相同的代码？我标记了每种方法不同的代码行。我遇到的问题是在不使用switch / case和改变回调对象的情况下调用特定的JSON解析函数。

//-----------------------differs-------------------------
public void getUser(final HTTPResponseCallback<User> callback)
{
    //-----------------------differs-------------------------
    final String url = domain + USERS;
    //-------------------------------------------------------

    okHttpClient.newCall(buildRequest(url)).enqueue(new Callback()
    {
        Handler handler = new Handler(Looper.getMainLooper());

        @Override
        public void onFailure(Call call, IOException e)
        {
            handler.post(new Runnable()
            {
                @Override
                public void run()
                {
                    callback.onFailure();
                }
            });
        }

        @Override
        public void onResponse(Call call, final Response response) throws IOException
        {
            if (response.isSuccessful())
            {
                try
                {
                    String responseBody = response.body().string();

                    //-----------------------differs-------------------------
                    JSONObject jsonResponse = new JSONObject(responseBody);
                    final User user = JsonParser.parseUser(jsonResponse
                    //------------------------------------------------------

                    handler.post(new Runnable()
                    {
                        @Override
                        public void run()
                        {
                            //---------------------------------------last parameter differs----------------------------------------------
                            callback.onSuccess(new HTTPTransaction(response.code(), response.message(), response.header("ETag")), user);
                            //-----------------------------------------------------------------------------------------------------------
                        }
                    });

                }
                catch (JSONException e)
                {
                    ...
                }
            }
            else
                ...

         }
    }
}

Answer 1

1）使用<T>参数化，因为类型可能不同：

public class CallBackWrapper<T> { 
    ...
    public void getUser(final HTTPResponseCallback<T> callback) { ...

2）为返回类型为T的实例的唯一部分引入回调对象：

interface Worker {
   T run(String responseBody);
}

public <T> void getUser(final HTTPResponseCallback<T> callback, Worker worker) { ...

3）调用所需的工人：

                String responseBody = response.body().string();

                //-----------------------differs-------------------------
                final T obj = worker.run(responseBody);
                //------------------------------------------------------

                handler.post(new Runnable()
                {
                    @Override
                    public void run()
                    {
                        //---------------------------------------last parameter differs----------------------------------------------
                        callback.onSuccess(new HTTPTransaction(response.code(), response.message(), response.header("ETag")), obj);
                        //-----------------------------------------------------------------------------------------------------------
                    }
                });

回调重复代码

1 个答案: