RecyclerView的下拉刷新與上拉加載更多

下拉刷新上拉加載更多,從設計層面上來說,就不是同一個層面上的,從Google官方推出的下拉刷新控件SwipeRefreshLayout就可以看出。
一般來說,下拉刷新是以包裹整個列表控件的容器來實現的,而上拉加載更多是以列表控件的一部分擴展(footerView)來實現的。

下拉刷新

  1. Google官方的SwipeRefreshLayout
    xml中控件初始化:
  <android.support.v4.widget.SwipeRefreshLayout
      android:layout_width="match_parent"
      android:layout_height="match_parent">

      <android.support.v7.widget.RecyclerView
          android:id="@+id/recyclerView"
          android:layout_width="match_parent"
          android:layout_height="match_parent"/>

  </android.support.v4.widget.SwipeRefreshLayout>

java類中實現

        // 設置下拉出現小圓圈是否是縮放出現,出現的位置,最大的下拉位置
        mySwipeRefreshLayout.setProgressViewOffset(true, 50, 200);

        // 設置下拉圓圈的大小,兩個值 LARGE, DEFAULT
        mySwipeRefreshLayout.setSize(SwipeRefreshLayout.LARGE);
        
        // 設置下拉圓圈上的顏色,藍色、綠色、橙色、紅色
        mySwipeRefreshLayout.setColorSchemeResources(
                android.R.color.holo_blue_bright,
                android.R.color.holo_green_light,
                android.R.color.holo_orange_light,
                android.R.color.holo_red_light);

        // 通過 setEnabled(false) 禁用下拉刷新
        mySwipeRefreshLayout.setEnabled(false);

        // 設定下拉圓圈的背景
        mSwipeLayout.setProgressBackgroundColor(R.color.red);

        /*
         * 設置手勢下拉刷新的監聽
         */
        mySwipeRefreshLayout.setOnRefreshListener(
                new SwipeRefreshLayout.OnRefreshListener() {
                    @Override
                    public void onRefresh() {
                        // 刷新動畫開始后回調到此方法
                    }
                }
        );
  1. 使用第三方下拉刷新控件,可以更好地支持自定義下拉樣式。
    這里推薦一個比較好的第三方控件:android-Ultra-Pull-To-Refresh
compile 'in.srain.cube:ultra-ptr:1.0.10'

xml中控件初始化:

    <in.srain.cube.views.ptr.PtrFrameLayout
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:id="@+id/refreshView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:ptr_duration_to_close="200"
        app:ptr_duration_to_close_header="1000"
        app:ptr_keep_header_when_refresh="true"
        app:ptr_pull_to_fresh="false"
        app:ptr_ratio_of_header_height_to_refresh="1.2"
        app:ptr_resistance="1.7">

        <com.zdf.zhihu.view.widget.LoadMoreRecyclerView
            android:id="@+id/recyclerView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

        </com.zdf.zhihu.view.widget.LoadMoreRecyclerView>

    </in.srain.cube.views.ptr.PtrFrameLayout>

java類中實現:

    private void initRefreshView() {
        // 這里可以完全自定義各種樣式,只要實現PtrUIHandler,
        // 具體請參考官方文檔也源碼
        MaterialHeader header = new MaterialHeader(getContext());
        refreshView.setHeaderView(header);
        refreshView.addPtrUIHandler(header);
        refreshView.setPtrHandler(new PtrDefaultHandler() {
            @Override
            public void onRefreshBegin(PtrFrameLayout ptrFrameLayout) {
                page = 0;
                requestTopMovies();
            }
        });
    }

    @Override
    public void autoRefresh() {
        handler.postDelayed(new Runnable() {
            @Override
            public void run() {
                refreshView.autoRefresh();
            }
        }, 100);
    }

    @Override
    public void refreshComplete() {
        handler.post(new Runnable() {
            @Override
            public void run() {
                refreshView.refreshComplete();
            }
        });
    }

上拉加載更多

以列表控件的一部分擴展實現,這里以RecyclerView為例,新建一個類LoadMoreRecyclerView,繼承至RecyclerView,主要的功能就是實現加載更多邏輯和顯示控件:

/**
 * 集成了上拉加載更多的RecyclerView
 *
 * Created by XiaoFeng on 2017/2/3.
 */
public class LoadMoreRecyclerView extends RecyclerView {

    private final int STATE_NONE = 0x00;
    private final int STATE_LOADING = 0x01;
    private final int STATE_FAILURE = 0x02;
    private final int STATE_COMPLETE = 0x03;

    // 滑到底部里最后一個個數的閥值
    private static final int VISIBLE_THRESHOLD = 1;

    private int state;
    private boolean loadMoreEnabled = true;
    private OnLoadMoreListener listener;
    private SuperAdapter superAdapter;
    private LoadMoreView loadMoreView;
    private LinearLayoutManager layoutManager;

    public LoadMoreRecyclerView(Context context) {
        this(context, null);
    }

    public LoadMoreRecyclerView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public LoadMoreRecyclerView(Context context, @Nullable AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public void initLoadMore(@NonNull OnLoadMoreListener listener) {
        this.listener = listener;

        if (getAdapter() instanceof SuperAdapter) {
            superAdapter = (SuperAdapter) getAdapter();
        }

        loadMoreView = new LoadMoreView(getContext());
        layoutManager = (LinearLayoutManager) getLayoutManager();

        addOnScrollListener(new OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
            }

            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);

                if (canLoadMore() && dy >= 0) {
                    int totalItemCount = layoutManager.getItemCount();
                    int lastVisibleItem = layoutManager.findLastVisibleItemPosition();
                    if (lastVisibleItem + VISIBLE_THRESHOLD >= totalItemCount) {
                        onLoadMore(recyclerView);
                    }
                }
            }
        });
    }

    public void setLoadMoreEnabled(boolean enabled) {
        this.loadMoreEnabled = enabled;
    }

    private boolean canLoadMore() {
        return state != STATE_LOADING && loadMoreEnabled;
    }

    private void onLoadMore(RecyclerView recyclerView) {
        state = STATE_LOADING;

        if (loadMoreView != null) {
            loadMoreView.loading();
        }

        recyclerView.post(new Runnable() {
            @Override
            public void run() {
                if (state == STATE_LOADING) {
                    if (superAdapter != null && loadMoreView != null) {
                        superAdapter.addFooterView(loadMoreView);
                    }
                }
            }
        });

        if (listener != null) {
            listener.onLoadMore();
        }
    }

    public void loadMoreFailed() {
        state = STATE_FAILURE;

        if (loadMoreView != null) {
            loadMoreView.failure();
        }

        if (superAdapter != null) {
            superAdapter.removeFooterView();
        }
    }

    public void loadMoreComplete() {
        state = STATE_COMPLETE;

        if (loadMoreView != null) {
            loadMoreView.complete();
        }

        if (superAdapter != null) {
            superAdapter.removeFooterView();
        }
    }
}

上面出現的SuperAdapter是使用了一個第三方封裝的萬能Adapter,同時支持ListView和RecyclerView,個人感覺比鴻洋大神封裝的萬能Adapter要好一些,但是基本原理都是一樣的。原理可以看他們各自的文章介紹,已經寫的很詳細了,這里就不多說了。

http://www.lxweimin.com/p/d6a76fd3ea5b
http://blog.csdn.net/lmj623565791/article/details/38902805
http://blog.csdn.net/lmj623565791/article/details/51118836

關于分頁加載

伴隨著上拉加載更多功能的,往往是分頁加載,關于分頁加載的頁數是在列表控件內部自動控制?還是在列表控件外部自己控制?我個人認為應該放在列表控件外部自己來控制頁數,因為這個頁數不光是在上拉加載更多時會使用到,在下拉刷新的時候也會使用到,并且對頁數需要清零。
這里提供一種在列表控件外部控制頁數的實現邏輯:

    // 分頁頁數
    private int page = 0;

    // 初始化下拉刷新控件
    private void initRefreshView() {
        MaterialHeader header = new MaterialHeader(getContext());
        refreshView.setHeaderView(header);
        refreshView.addPtrUIHandler(header);
        refreshView.setPtrHandler(new PtrDefaultHandler() {
            @Override
            public void onRefreshBegin(PtrFrameLayout ptrFrameLayout) {
                page = 0;
                requestTopMovies();
            }
        });
    }

    // 初始化RecyclerView,包含上拉加載更多
    private void initRecyclerView() {
        recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
        adapter = new SubjectAdapter(getContext());
        recyclerView.setAdapter(adapter);
        recyclerView.initLoadMore(new OnLoadMoreListener() {
            @Override
            public void onLoadMore() {
                page++;
                requestTopMovies();
            }
        });
    }

    // 具有分頁操作的網絡請求
    private void requestTopMovies() {
        Subscriber subscriber = new RxCallback<List<Movie>>() {
            @Override
            public void onSuccess(List<Movie> movieList) {
                if (adapter != null) {
                    if (page == 0) {
                        adapter.clear();
                    } else {
                        recyclerView.loadMoreComplete();
                    }
                    adapter.addAll(movieList);
                }
            }

            @Override
            public void onFinished() {
                refreshComplete();
            }
        };
        RxRetrofitClient.getInstance().requestTop250Movies(subscriber, page, 10);
    }

參考:
https://github.com/hanks-zyh/SwipeRefreshLayout
http://www.lxweimin.com/p/d6a76fd3ea5b
http://blog.csdn.net/lmj623565791/article/details/38902805
http://blog.csdn.net/lmj623565791/article/details/51118836

最后編輯于
?著作權歸作者所有,轉載或內容合作請聯系作者
平臺聲明:文章內容(如有圖片或視頻亦包括在內)由作者上傳并發布,文章內容僅代表作者本人觀點,簡書系信息發布平臺,僅提供信息存儲服務。

推薦閱讀更多精彩內容