【Android-自定义控件】SwipeRefreshDemo 下拉刷新，上拉加载

参考：https://github.com/PingerOne/SwipeRefreshDemo

谷歌官方的SwipeRefreshLayout控件，只有下拉刷新功能。
自定义的SwipeRefreshView ，继承自SwipeRefreshLayout，添加了上拉加载更多功能，添加对RecyclerView的支持。

添加“加载更多”底部布局 swiperefreshview_footer.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="48dp">

        <ProgressBar
            android:id="@+id/load_progress"
            android:layout_width="24dp"
            android:layout_height="24dp"
            android:layout_centerVertical="true"
            android:layout_marginLeft="30dp"/>

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:text="正在努力加载中..."
            android:textColor="@android:color/black"
            android:textSize="16sp"/>

    </RelativeLayout>

</RelativeLayout>

自定义view - SwipeRefreshView

/**
 * 自定义View继承SwipeRefreshLayout
 * 添加上拉加载更多的布局属性
 * 添加对RecyclerView的支持
 */

public class SwipeRefreshView extends SwipeRefreshLayout {

    private static final String TAG = SwipeRefreshView.class.getSimpleName();
    private final int mScaledTouchSlop;
    private final View mFooterView;
    private ListView mListView;
    private OnLoadMoreListener mListener;

    /**
     * 正在加载状态
     */
    private boolean isLoading;

    private RecyclerView mRecyclerView;

    private int mItemCount;

    public SwipeRefreshView(Context context, AttributeSet attrs) {
        super(context, attrs);
        // 填充底部加载布局
        mFooterView = View.inflate(context, R.layout.swiperefreshview_footer, null);

        // 表示控件移动的最小距离，手移动的距离大于这个距离才能拖动控件
        mScaledTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
        // 获取ListView,设置ListView的布局位置
        if (mListView == null || mRecyclerView == null) {
            // 判断容器有多少个孩子
            if (getChildCount() > 0) {
                // 判断第一个孩子是否是ListView
                if (getChildAt(0) instanceof ListView) {
                    // 建立ListView对象
                    mListView = (ListView) getChildAt(0);

                    // 设置ListView的滑动监听
                    setListViewOnScroll();
                } else if (getChildAt(0) instanceof RecyclerView) {
                    // 建立ListView对象
                    mRecyclerView = (RecyclerView) getChildAt(0);

                    // 设置RecyclerView的滑动监听
                    setRecyclerViewOnScroll();
                }
            }
        }
    }


    /**
     * 在分发事件的时候处理子控件的触摸事件
     */
    private float mDownY, mUpY;

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {

        switch (ev.getAction()) {
            case MotionEvent.ACTION_DOWN:
                // 移动的起点
                mDownY = ev.getY();
                break;
            case MotionEvent.ACTION_MOVE:
                // 移动过程当中判断时候能下拉加载更多
                if (canLoadMore()) {
                    // 加载数据
                    loadData();
                }

                break;
            case MotionEvent.ACTION_UP:
                // 移动的终点
                mUpY = getY();
                break;
        }
        return super.dispatchTouchEvent(ev);
    }

    /**
     * 判断是否知足加载更多条件
     */
    private boolean canLoadMore() {
        // 1. 是上拉状态
        boolean condition1 = (mDownY - mUpY) >= mScaledTouchSlop;
        if (condition1) {
            Log.d(TAG, "------->  是上拉状态");
        }

        // 2. 当前页面可见的item是最后一个条目,通常最后一个条目位置须要大于第一页的数据长度
        boolean condition2 = false;
        if (mListView != null && mListView.getAdapter() != null) {

            if (mItemCount > 0) {
                if (mListView.getAdapter().getCount() < mItemCount) {
                    // 第一页未满，禁止下拉
                    condition2 = false;
                }else {
                    condition2 = mListView.getLastVisiblePosition() == (mListView.getAdapter().getCount() - 1);
                }
            } else {
                // 未设置数据长度，则默认第一页数据不满时也能够上拉
                condition2 = mListView.getLastVisiblePosition() == (mListView.getAdapter().getCount() - 1);
            }

        }

        if (condition2) {
            Log.d(TAG, "------->  是最后一个条目");
        }
        // 3. 正在加载状态
        boolean condition3 = !isLoading;
        if (condition3) {
            Log.d(TAG, "------->  不是正在加载状态");
        }
        return condition1 && condition2 && condition3;
    }

    public void setItemCount(int itemCount) {
        this.mItemCount = itemCount;
    }

    /**
     * 处理加载数据的逻辑
     */
    private void loadData() {
        System.out.println("加载数据...");
        if (mListener != null) {
            // 设置加载状态，让布局显示出来
            setLoading(true);
            mListener.onLoadMore();
        }

    }

    /**
     * 设置加载状态，是否加载传入boolean值进行判断
     *
     * @param loading
     */
    public void setLoading(boolean loading) {
        // 修改当前的状态
        isLoading = loading;
        if (isLoading) {
            // 显示布局
            mListView.addFooterView(mFooterView);
        } else {
            // 隐藏布局
            mListView.removeFooterView(mFooterView);

            // 重置滑动的坐标
            mDownY = 0;
            mUpY = 0;
        }
    }


    /**
     * 设置ListView的滑动监听
     */
    private void setListViewOnScroll() {

        mListView.setOnScrollListener(new AbsListView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {
                // 移动过程当中判断时候能下拉加载更多
                if (canLoadMore()) {
                    // 加载数据
                    loadData();
                }
            }

            @Override
            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {

            }
        });
    }


    /**
     * 设置RecyclerView的滑动监听
     */
    private void setRecyclerViewOnScroll() {
        mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
                // 移动过程当中判断时候能下拉加载更多
                if (canLoadMore()) {
                    // 加载数据
                    loadData();
                }
            }

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


    /**
     * 上拉加载的接口回调
     */

    public interface OnLoadMoreListener {
        void onLoadMore();
    }

    public void setOnLoadMoreListener(OnLoadMoreListener listener) {
        this.mListener = listener;
    }
}

应用布局

<com.example.customview.SwipeRefreshView
        android:id="@+id/swipeRefreshView"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ListView
            android:id="@+id/listView"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

        </ListView>
    </com.example.customview.SwipeRefreshView>

应用代码

/**
 * 使用自定义的SwipeRefreshView
 */

public class RefreshActicity extends AppCompatActivity {

    SwipeRefreshView swipeRefreshView;
    ListView listView;
    List<Product> list;
    ProductAdapter adapter;


    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_refresh);

        swipeRefreshView = findViewById(R.id.swipeRefreshView);
        listView = findViewById(R.id.listView);

        //设置适配器
        list=new ArrayList<>();
        adapter = new ProductAdapter(this, list);
        listView.setAdapter(adapter);


        //设置下拉进度的背景颜色，默认是白色
        swipeRefreshView.setProgressBackgroundColorSchemeResource(android.R.color.white);
        //设置下拉进度的肢体颜色
        swipeRefreshView.setColorSchemeResources(R.color.colorAccent, R.color.colorPrimary, R.color.colorPrimaryDark);

        swipeRefreshView.setItemCount(20);

        // 手动调用,通知系统去测量
         swipeRefreshView.measure(0,0);
         swipeRefreshView.setRefreshing(true);

        initData();

        //下拉时触发SwipeRefreshLayout的下拉动画，动画完毕后回调这个方法
        swipeRefreshView.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                initData();
            }
        });

        //设置下拉加载更多
        swipeRefreshView.setOnLoadMoreListener(new SwipeRefreshView.OnLoadMoreListener() {
            @Override
            public void onLoadMore() {

              loadMoreData();
            }
        });

    }


    /**
     * 第一次刷新数据
     */
    private void initData()
    {
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                list.clear();
                list.addAll(DataResource.getData());
                adapter.notifyDataSetChanged();
                //加载完数据，设置为不刷新状态，将下拉进度收起来
                swipeRefreshView.setRefreshing(false);
                Toast.makeText(RefreshActicity.this, "刷新了20条数据", Toast.LENGTH_SHORT).show();

                // 加载完数据设置为不刷新状态，将下拉进度收起来
                if (swipeRefreshView.isRefreshing()) {
                    swipeRefreshView.setRefreshing(false);
                }
            }
        }, 2000);
    }

    /**
     * 加载更多数据
     */
    private void loadMoreData()
    {
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {

                list.clear();
                list.addAll(DataResource.getMoreData());
                Toast.makeText(RefreshActicity.this, "加载了" + 20 + "条数据", Toast.LENGTH_SHORT).show();
                // 加载完数据设置为不加载状态，将加载进度收起来
                swipeRefreshView.setLoading(false);
            }
        }, 2000);
    }

    public static class DataResource {
        private static List<Product> datas = new ArrayList<>();
        private static int page = 0;

        //第一次加载数据
        public static List<Product> getData() {
            page = 0;
            datas.clear();
            for (int i = 0; i < 20; i++) {
                Random random = new Random();
                Product product = new Product("100" + (i+1), "testdata", random.nextInt(100));
                datas.add(product);
            }
            return datas;
        }

        //加载更多数据
        public static List<Product> getMoreData() {
            page = page + 1;
            for (int i = 20 * page; i < 20 * (page + 1); i++) {
                Random random = new Random();
                Product product = new Product("100" + (i+1), "testdata", random.nextInt(100));
                datas.add(product);
            }
            return datas;
        }

    }

}