SwipeRefreshLayout如何仅在从顶部下拉时触发刷新？

我有一个嵌套RecyclerView的SwipeRefreshLayout，布局代码如下：

<androidx.swiperefreshlayout.widget.SwipeRefreshLayout
    android:id="@+id/swipeRefreshLayout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/catalog_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</androidx.swiperefreshlayout.widget.SwipeRefreshLayout>

需求：仅在从可滚动区域初始顶部位置开始下拉时触发刷新；若用户先滚动过RecyclerView内容，再回到顶部后下拉，则不触发刷新。

实现方案 #

SwipeRefreshLayout没有原生配置项支持该逻辑，需要通过监听RecyclerView滚动状态，结合自定义View或动态控制刷新组件的启用状态来实现。

方案一：自定义SwipeRefreshLayout（推荐） #

通过重写嵌套滚动的拦截方法，精准控制触发刷新的时机：

1. 自定义继承SwipeRefreshLayout的类：

public class CustomSwipeRefreshLayout extends SwipeRefreshLayout {
    private RecyclerView mRecyclerView;
    private boolean hasRecyclerViewScrolled = false;

    public CustomSwipeRefreshLayout(@NonNull Context context) {
        super(context);
    }

    public CustomSwipeRefreshLayout(@NonNull Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public void setRecyclerView(RecyclerView recyclerView) {
        mRecyclerView = recyclerView;
        mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
                // 只要RecyclerView发生过滚动，标记状态
                if (dx != 0 || dy != 0) {
                    hasRecyclerViewScrolled = true;
                }
            }
        });
    }

    @Override
    public boolean onStartNestedScroll(@NonNull View child, @NonNull View target, int axes, int type) {
        // 仅当RecyclerView在顶部，且从未被滚动过，才允许触发下拉刷新
        boolean isAtTop = !mRecyclerView.canScrollVertically(-1);
        return isAtTop && !hasRecyclerViewScrolled && super.onStartNestedScroll(child, target, axes, type);
    }

    // 重置滚动状态（比如刷新完成后，允许再次从初始顶部触发刷新）
    public void resetScrollState() {
        hasRecyclerViewScrolled = false;
    }
}

2. 替换布局中的SwipeRefreshLayout：

<com.yourpackage.CustomSwipeRefreshLayout
    android:id="@+id/swipeRefreshLayout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/catalog_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</com.yourpackage.CustomSwipeRefreshLayout>

3. 在代码中初始化并设置监听：

CustomSwipeRefreshLayout swipeRefreshLayout = findViewById(R.id.swipeRefreshLayout);
RecyclerView catalogRecyclerView = findViewById(R.id.catalog_recycler_view);
swipeRefreshLayout.setRecyclerView(catalogRecyclerView);

swipeRefreshLayout.setOnRefreshListener(() -> {
    // 执行刷新逻辑
    // ...
    // 刷新完成后停止加载动画
    swipeRefreshLayout.setRefreshing(false);
    // 可选：重置滚动状态，允许下次从初始顶部触发刷新
    swipeRefreshLayout.resetScrollState();
});

方案二：动态控制SwipeRefreshLayout的启用状态 #

无需自定义View，通过RecyclerView的滚动监听器动态设置SwipeRefreshLayout是否可用：

private boolean hasRecyclerViewScrolled = false;
private SwipeRefreshLayout swipeRefreshLayout;
private RecyclerView catalogRecyclerView;

// 初始化组件
swipeRefreshLayout = findViewById(R.id.swipeRefreshLayout);
catalogRecyclerView = findViewById(R.id.catalog_recycler_view);

// 监听RecyclerView滚动状态
catalogRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
    @Override
    public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);
        if (dx != 0 || dy != 0) {
            hasRecyclerViewScrolled = true;
        }
        // 仅当RecyclerView在顶部且未滚动过时，启用下拉刷新
        boolean isAtTop = !recyclerView.canScrollVertically(-1);
        swipeRefreshLayout.setEnabled(isAtTop && !hasRecyclerViewScrolled);
    }
});

// 设置刷新监听器
swipeRefreshLayout.setOnRefreshListener(() -> {
    // 执行刷新逻辑
    // ...
    swipeRefreshLayout.setRefreshing(false);
    // 重置滚动状态
    hasRecyclerViewScrolled = false;
});

内容的提问来源于stack exchange，提问作者Pierre de LESPINAY