关于fragment+viewpager的优化

转载请加入链接，谢谢：http://blog.csdn.net/u013173289/article/details/44002371

上次写了一个问答项目，用的fragment+viewpager架构，后来发现，划了几次之后，再划回来，会重新加载布局，重新获取数据，这样整个程序和卡，并且占用太多的网络资源。

当时的解决办法是，自己重写view，用最基本的Basepageradapder,算是不是很优雅的解决了问题。

当时知道是重新调用onCreateView方法原因，但是没有好的解决办法，现在知道了，这里记载一下。

我实验了viewpager加载四个fragment：

第一次进入的时候：

<span style="font-size:18px;">03-01 13:50:16.151  22667-22667/com.graypn.modelproject I/onCreate1﹕ onCreate
03-01 13:50:16.151  22667-22667/com.graypn.modelproject I/onCreateView1﹕ onCreateView
03-01 13:50:16.161  22667-22667/com.graypn.modelproject I/onActivityCreated1﹕ onActivityCreated
03-01 13:50:16.161  22667-22667/com.graypn.modelproject I/onCreate2﹕ onCreate
03-01 13:50:16.161  22667-22667/com.graypn.modelproject I/onCreateView2﹕ onCreateView
03-01 13:50:16.161  22667-22667/com.graypn.modelproject I/onActivityCreated2﹕ onActivityCreated</span>

<span style="font-size:18px;">03-01 13:51:22.391  22667-22667/com.graypn.modelproject I/onCreate3﹕ onCreate
03-01 13:51:22.391  22667-22667/com.graypn.modelproject I/onCreateView3﹕ onCreateView
03-01 13:51:22.401  22667-22667/com.graypn.modelproject I/onActivityCreated3﹕ onActivityCreated</span>

03-01 13:55:24.351  24165-24165/com.graypn.modelproject I/onDestroyView1﹕ onDestroyView
03-01 13:55:24.351  24165-24165/com.graypn.modelproject I/onCreate4﹕ onCreate
03-01 13:55:24.351  24165-24165/com.graypn.modelproject I/onCreateView4﹕ onCreateView
03-01 13:55:24.361  24165-24165/com.graypn.modelproject I/onActivityCreated4﹕ onActivityCreated

03-01 13:56:22.021  24165-24165/com.graypn.modelproject I/onDestroyView2﹕ onDestroyView

03-01 13:58:09.541  24165-24165/com.graypn.modelproject I/onCreateView2﹕ onCreateView
03-01 13:58:09.541  24165-24165/com.graypn.modelproject I/onActivityCreated2﹕ onActivityCreated

我们需要优化自己的fragment，如下时我优化后的类：

<span style="font-size:18px;">/**
 * 提供了fragment的封装后基类，提供context给子类使用
 *
 * @author Graypn
 */
public abstract class BaseFragment extends Fragment {

    //根部view
    private View rootView;
    protected Context context;
    private Boolean hasInitData = false;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        context = getActivity();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        if (rootView == null) {
            rootView = initView(inflater);
        }
        return rootView;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        if (!hasInitData) {
            initData();
            hasInitData = true;
        }
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        ((ViewGroup) rootView.getParent()).removeView(rootView);
    }

    /**
     * 子类实现初始化View操作
     */
    protected abstract View initView(LayoutInflater inflater);

    /**
     * 子类实现初始化数据操作(子类自己调用)
     */
    public abstract void initData();

    /**
     * 封装从网络下载数据
     */
    protected void loadData(HttpRequest.HttpMethod method, String url,
                            RequestParams params, RequestCallBack<String> callback) {
        if (0 == NetUtils.isNetworkAvailable(getActivity())) {
            new CustomToast(getActivity(), "无网络，请检查网络连接！", 0).show();
        } else {
            NetUtils.loadData(method, url, params, callback);
        }
    }

}</span>

加入判断是否已经加载数据完成的标志变量，如果已经加载了数据，就不重新加载数据。

算是优雅的解决了优化的问题，希望能帮到有同样问题的同学。