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我有两个类 - 一个定义BaseActivity（我在应用程序中的所有活动的全局父级），另一个是AsyncTask我定义公共网络操作的类。但我有下一个问题。在他的方法中AsyncTask命名的类必须调用在类中定义的类，但类也必须创建一个. 这是清楚地说明了这个问题的代码。RestfulNetworkTasksonPostExecute()UpdateCurrentActivityAfterNetworkOperation()BaseActivityBaseActivityRestfulNetworkTasks

class RestfulNetworkTasks extends AsyncTask<Pair<String, LinkedHashMap<String, Object>>, Void, LinkedHashMap<String, Object>> {
    private ImmutableMap<String, Object> serverData_;
    NetworkOperation LowLevelRestOperations_ = new NetworkOperation();

    @Override
    protected LinkedHashMap<String, Object> doInBackground(Pair<String, LinkedHashMap<String, Object>>... params) {
        return LowLevelRestOperations_.executeServerCommand(params[0].getValue0(), params[0].getValue1());
    }

    protected void onPostExecute(LinkedHashMap<String, Object> result) {
        serverData_ = copyOf(result);
        BaseActivity instance_Activity = new BaseActivity(); 
        //BaseActivity injection (It is too bad to create Activity in such a way - I know!) So I need some piece of advice
        instance_Activity.UpdateCurrentActivityAfterNetworkOperation(serverData_);
        //Here I must call method for updating GUI after operation
    }

    public ImmutableMap<String, Object> GetDataFromServer() {
        return serverData_;
    }
}

public class BaseActivity extends Activity {

    RestfulNetworkTasks serverOperation_ = new RestfulNetworkTasks(); //RestfulNetworkTasks injection

    public void UpdateCurrentActivityAfterNetworkOperation(
        ImmutableMap<String, Object> server_data) {
    }// Here is this method which I will override in my child activities

    @SuppressWarnings("unchecked")
    public ImmutableMap<String, Object> Login(LinkedHashMap<String, Object> parameters) {
        Pair<String, LinkedHashMap<String, Object>> params_ = new Pair<String, LinkedHashMap<String, Object>>(LOGIN_COMMAND, parameters);
        serverOperation_.execute(params_);
        return serverOperation_.GetDataFromServer();
    }
}

如您所见，我在 RestfulNetworkTasks 和 BaseActivity 类之间存在循环依赖关系，这可能导致构造函数的无限链调用。

问题是如何重构这个设计来避免这种情况？

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2 回答 2

3

AsyncTask 几乎总是会从 Activity 中调用，那么为什么不将它作为 Constructor 参数传入呢？

RestfulNetworkTasks.java：

private BaseActivity activity;

public RestfulNetworkTasks(BaseActivity activity){
    this.activity = activity;
}

BaseActivity.java：

new RestfulNetworkTasks(this).execute();
于 2013-02-22T09:26:33.760 回答
1

您不应该以这种方式创建 Activity

BaseActivity instance_Activity = new BaseActivity();

活动由系统管理

于 2013-02-22T08:59:19.307 回答