安卓将view拖拽进入recycleview示例代码

这里是一个示例代码，演示如何将一个 View 拖拽进入 RecyclerView 中：

1. 首先，在布局文件中定义 RecyclerView：

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

2. 在 Activity 或 Fragment 中获取 RecyclerView 实例，并设置其布局管理器：

RecyclerView recyclerView = findViewById(R.id.recycler_view);
recyclerView.setLayoutManager(new LinearLayoutManager(this));

3. 创建一个自定义的 RecyclerView.Adapter 类，用于管理数据集合，并将数据绑定到 View 上：

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
    private List<String> mData;

    public MyAdapter(List<String> data) {
        mData = data;
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.item_view, parent, false);
        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        String data = mData.get(position);
        holder.mTextView.setText(data);
    }

    @Override
    public int getItemCount() {
        return mData.size();
    }

    public static class MyViewHolder extends RecyclerView.ViewHolder {
        public TextView mTextView;

        public MyViewHolder(View itemView) {
            super(itemView);
            mTextView = itemView.findViewById(R.id.text_view);
        }
    }
}

4. 在 Activity 或 Fragment 中创建一个 Adapter 实例，并将其设置为 RecyclerView 的适配器：

List<String> data = Arrays.asList("Item 1", "Item 2", "Item 3");
MyAdapter adapter = new MyAdapter(data);
recyclerView.setAdapter(adapter);

5. 实现 ItemTouchHelper.Callback 接口，用于处理拖拽和滑动事件：

public class MyItemTouchHelperCallback extends ItemTouchHelper.Callback {
    private final ItemTouchHelperAdapter mAdapter;

    public MyItemTouchHelperCallback(ItemTouchHelperAdapter adapter) {
        mAdapter = adapter;
    }

    @Override
    public boolean isLongPressDragEnabled() {
        return true;
    }

    @Override
    public boolean isItemViewSwipeEnabled() {
        return false;
    }

    @Override
    public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        // 允许上下拖拽
        int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
        // 不允许滑动
        int swipeFlags = 0;
        return makeMovementFlags(dragFlags, swipeFlags);
    }

    @Override
    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder,
                          RecyclerView.ViewHolder target) {
        mAdapter.onItemMove(viewHolder.getAdapterPosition(), target.getAdapterPosition());
        return true;
    }

    @Override
    public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
        // 不处理滑动事件
    }
}

6. 创建一个 ItemTouchHelperAdapter 接口，用于处理拖拽事件：

public interface ItemTouchHelperAdapter {
    void onItemMove(int fromPosition, int toPosition);
}

7. 在 Adapter 类中实现 ItemTouchHelperAdapter 接口：

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder>
        implements ItemTouchHelperAdapter {
    private List<String> mData;

    public MyAdapter(List<String> data) {
        mData = data;
    }

    // 省略 onCreateViewHolder 和 onBindViewHolder 方法

    @Override
    public int getItemCount() {
        return mData.size();
    }

    @Override
    public void onItemMove(int fromPosition, int toPosition) {
        // 处理拖拽事件
        String data = mData.remove(fromPosition);
        mData.add(toPosition, data);
        notifyItemMoved(fromPosition, toPosition);
    }

    public static class MyViewHolder extends RecyclerView.ViewHolder {
        public TextView mTextView;

        public MyViewHolder(View itemView) {
            super(itemView);
            mTextView = itemView.findViewById(R.id.text_view);
        }
    }
}

8. 在 Activity 或 Fragment 中创建一个 ItemTouchHelper 实例，并将其附加到 RecyclerView 上：

ItemTouchHelper.Callback callback = new MyItemTouchHelperCallback(adapter);
ItemTouchHelper itemTouchHelper = new ItemTouchHelper(callback);
itemTouchHelper.attachToRecyclerView(recyclerView);

9. 如果需要在拖拽的过程中显示一个提示，可以在 MyViewHolder 中添加一个 View，并在 onItemSelected 和 onItemClear 方法中修改其可见性：

public static class MyViewHolder extends RecyclerView.ViewHolder
        implements ItemTouchHelperViewHolder {
    public TextView mTextView;
    public View mDragHandle;

    public MyViewHolder(View itemView) {
        super(itemView);
        mTextView = itemView.findViewById(R.id.text_view);
        mDragHandle = itemView.findViewById(R.id.drag_handle);
    }

    @Override
    public void onItemSelected() {
        mDragHandle.setVisibility(View.VISIBLE);
    }

    @Override
    public void onItemClear() {
        mDragHandle.setVisibility(View.GONE);
    }
}

10. 最后，在布局文件中为 MyViewHolder 添加一个拖拽手柄：

<ImageView
    android:id="@+id/drag_handle"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/ic_drag_handle"
    android:visibility="gone" />