用于HTTP请求的AsyncTaskLoader，用于使用泛型，继承来处理方向更改

用于HTTP请求的AsyncTaskLoader，用于使用泛型，继承来处理方向更改

好的，这就是我想出的，它实际上似乎工作得很好，并且可以在后台工作期间处理屏幕方向更改。这是我更新的HttpAsyncTaskLoader。

public class HttpAsyncTaskLoader<T extends ApiResponse> extends AsyncTaskLoader {    private ApiClient mClient ;    protected ApiRequest mRequest;    private ApiResponse mResponse;    private volatile boolean isExecuting = false;    public HttpAsyncTaskLoader(Context context, ApiClient client, ApiRequest request) {        super(context);        mClient = client;        mRequest = request;    }        protected ApiResponse executeRequest(ApiRequest request) {        HttpResponse response = null;        ResponseError error = null;        JSonObject responseJson = null;        try { isExecuting = true; Log.d(TAG, "executing api"); response  =  mClient.execute(request); Log.d(TAG, "got a response"); isExecuting = false; responseJson = new JSonObject(EntityUtils.toString(response.getEntity())); Log.d(TAG, "parsed response to json");        } catch (IOException e) { error = new ResponseError(e);        } catch (URISyntaxException e) { error = new ResponseError(e);        } catch (JSonException e) { error = new ResponseError(e);        } finally { mClient.getConnectionManager().closeExpiredConnections(); isExecuting = false; mResponse = new ApiResponse(getContext().getResources(), response, responseJson, error);        }        return mResponse;    }    protected void onStartLoading() {        super.onStartLoading();        if (takeContentChanged() ||  mResponse == null) { forceLoad();        }        if (getResponse() != null) { deliverResult(getResponse());        }    }        public ApiResponse getResponse() {        return mResponse;    }    @Override    public void onCanceled(Object data) {        super.onCanceled(data);        if (isExecuting) { mClient.getConnectionManager().shutdown();        }    }    @Override    public ApiResponse loadInBackground() {        return executeRequest(mRequest);    }}

请注意，在上面的示例中，onCanceled方法采用一个Object。如果尝试使用ApiResponse，则会出现编译错误。作为类型。另外，您必须像上面一样实现onStartLoading（如果结果对象为null，则调用forceLoad），否则不会调用loadInBackground

接下来是HttpAsyncTaskLoader子类的示例：

public class LoginAsyncTaskLoader extends HttpAsyncTaskLoader {    private LoginResponse mLoginResponse;    public LoginAsyncTaskLoader(Context context, ApiClient client, ApiRequest request) {        super(context, client, request);    }    @Override    public LoginResponse loadInBackground() {        ApiResponse apiResponse = executeRequest(mRequest);        mLoginResponse = new LoginResponse(apiResponse.getResources(), apiResponse.response, apiResponse.responseJson, apiResponse.getError());        return mLoginResponse;    }    @Override    public ApiResponse getResponse() {        return mLoginResponse;    }}

这是使用此加载程序的活动：

public class LoginActivity extends FragmentActivity implements LoaderManager.LoaderCallbacks<LoginResponse> {    private String username,password;@Override    protected void onCreate(Bundle savedInstanceState) {        // TODO Auto-generated method stub        super.onCreate(savedInstanceState);        setContentView(R.layout.login);        Loader loader = getSupportLoaderManager().getLoader(0);        if (loader != null) { getSupportLoaderManager().initLoader(0, null, this);        }    }    public void loginSubmit(View button) { Bundle data = new Bundle(); data.putString("username", getUsername()); data.putString("password", getPassword());   getSupportLoaderManager().restartLoader(0, data, this);    }    @Override    public Loader<LoginResponse> onCreateLoader(int i, Bundle bundle) {    //might want to start a progress bar        ApiClient client = new ApiClient();        LoginApi loginApi = new LoginApi(bundle.getString("username"), bundle.getString("password"));        return new LoginAsyncTaskLoader(this, apiClient, loginApi);    }    @Override    public void onLoadFinished(Loader<LoginResponse> loginLoader,         LoginResponse loginResponse)    {        //handle result, maybe send to a new activity if response doesn't have an error    }    @Override    public void onLoaderReset(Loader<LoginResponse> responseAndJsonHolderLoader)    {        //not sure if anything needs to be done here to do    }}

请注意，虽然该加载器直到用户按下“登录”按钮才启动，但是如果已经进行了，则必须使用onCreate中的initLoader重新连接到加载器，以防它已经在进行中；否则，当您翻转方向时，您将不会收到任务完成的通知。
。

有趣的是，这似乎很好用，不需要使用TaskFragment。我还没有真正看到其他人为http做这些事情，所以也许有一些缺点，但似乎工作得很好。