【Android -- UI 开发】RecyclerView 实现拖拽 + 固定首个效果

仿腾讯视频中全部频道界面，首个精选长按不能拖动，其余的可以拖动。

效果图

1、添加依赖

	//Butter Knife
    implementation 'com.jakewharton:butterknife:10.2.1'
    annotationProcessor 'com.jakewharton:butterknife-compiler:10.2.0'

    //TitleBar
    implementation 'com.github.getActivity:TitleBar:8.6'

2、布局文件

3、逻辑代码

1. GridActivity.java

public class GirdActivity extends BaseActivity {
    @BindView(R.id.rv_gird)
    RecyclerView mRecyclerView;

    private GirdAdapter mAdapter;
    List mStringList;

    @Override
    protected int getLayoutId() {
        return R.layout.activity_gird;
    }

    @Override
    protected void initView() {
        if (mStringList == null) {
            mStringList = new ArrayList();
        }
        mStringList.addAll(DataManager.getData(9));
        mAdapter = new GirdAdapter(R.layout.grid_item, mStringList, true);

        mRecyclerView.setLayoutManager(new GridLayoutManager(this, 4));
        mRecyclerView.addItemDecoration(new MyItemDecoration());
        mRecyclerView.setHasFixedSize(true);

        RecyItemTouchHelperCallback itemTouchHelperCallback = new RecyItemTouchHelperCallback(mAdapter, false, true);
        final ItemTouchHelper itemTouchHelper = new ItemTouchHelper(itemTouchHelperCallback);
        itemTouchHelper.attachToRecyclerView(mRecyclerView);

        mRecyclerView.addOnItemTouchListener(new OnRecyclerItemClickListener(mRecyclerView) {
            @Override
            public void onItemClick(RecyclerView.ViewHolder viewHolder) {
                GirdAdapter.ViewHolder viewHolder1 = (GirdAdapter.ViewHolder) viewHolder;
                String tvString = viewHolder1.mTextView.getText().toString();
                Toast.makeText(GirdActivity.this, "点击了..." + tvString, Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onLongClick(RecyclerView.ViewHolder viewHolder) {
                Toast.makeText(GirdActivity.this, "" + "长按拖动...", Toast.LENGTH_SHORT).show();
                if (viewHolder.getLayoutPosition() != 0) {
                    itemTouchHelper.startDrag(viewHolder);
                }
            }
        });
        mRecyclerView.setAdapter(mAdapter);
    }

    public static class MyItemDecoration extends RecyclerView.ItemDecoration{
        @Override
        public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
            outRect.set(0,0,20,20);
        }
    }
}

2. 适配器代码

public class GirdAdapter extends RecyclerView.Adapter {
    private int item_layout;
    private List mDataList;
    private List mInts;
    private boolean isFirstSpecial;

    public GirdAdapter(int item_layout, List dataList) {
        this.item_layout = item_layout;
        mDataList = dataList;
        mInts = Arrays.asList(R.mipmap.ic_apple, R.mipmap.ic_banana,
                R.mipmap.ic_cherry, R.mipmap.ic_grape,
                R.mipmap.ic_mango, R.mipmap.ic_pineapple,
                R.mipmap.ic_orange, R.mipmap.ic_pear, R.mipmap.ic_strawberry);
    }

    public GirdAdapter(int item_layout, List dataList, boolean isFirstSpecial) {
        this(item_layout, dataList);
        this.isFirstSpecial = isFirstSpecial;
    }

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

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        String string = mDataList.get(position);
        if (isFirstSpecial && position == 0) {
            holder.itemView.setBackgroundColor(Color.LTGRAY);
            holder.mTextView.setText("苹果");
            holder.mImageView.setImageResource(R.mipmap.ic_apple);
        } else {
            holder.itemView.setBackgroundColor(Color.WHITE);
            holder.mTextView.setText(string);
            holder.mImageView.setImageResource(mInts.get(position % mInts.size()));
        }
    }

    @Override
    public int getItemCount() {
        return mDataList == null ? 0 : mDataList.size();
    }

    public List getDataList() {
        return mDataList;
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        public TextView mTextView;
        ImageView mImageView;

        ViewHolder(View itemView) {
            super(itemView);
            mTextView = (TextView) itemView.findViewById(R.id.tv_title);
            mImageView = (ImageView) itemView.findViewById(R.id.img_item);
        }
    }
}

3. RecyclerView 点击事件

/**
 * Created on 2022/3/19 14:30
 *
 * @author Gong Youqiang
 */
public abstract class OnRecyclerItemClickListener implements RecyclerView.OnItemTouchListener {
    private GestureDetectorCompat mGestureDetectorCompat;
    private RecyclerView mRecyclerView;

    public OnRecyclerItemClickListener(RecyclerView recyclerView) {
        mRecyclerView = recyclerView;
        mGestureDetectorCompat = new GestureDetectorCompat(mRecyclerView.getContext(),
                new ItemTouchHelperGestureListener());
    }

    @Override
    public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {
        mGestureDetectorCompat.onTouchEvent(e);
        return false;
    }

    @Override
    public void onTouchEvent(RecyclerView rv, MotionEvent e) {
        mGestureDetectorCompat.onTouchEvent(e);
    }

    @Override
    public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {

    }

    public abstract void onItemClick(RecyclerView.ViewHolder viewHolder);
    public abstract void onLongClick(RecyclerView.ViewHolder viewHolder);

    private class ItemTouchHelperGestureListener extends GestureDetector.SimpleOnGestureListener{
        @Override
        public boolean onSingleTapUp(MotionEvent e) {
            View childViewUnder = mRecyclerView.findChildViewUnder(e.getX(), e.getY());
            if (childViewUnder != null) {
                RecyclerView.ViewHolder childViewHolder = mRecyclerView.getChildViewHolder(childViewUnder);
                onItemClick(childViewHolder);
            }
            return true;
        }

        @Override
        public void onLongPress(MotionEvent e) {
            View childViewUnder = mRecyclerView.findChildViewUnder(e.getX(), e.getY());
            if (childViewUnder != null) {
                RecyclerView.ViewHolder childViewHolder = mRecyclerView.getChildViewHolder(childViewUnder);
                onLongClick(childViewHolder);
            }
        }
    }
}

4. 长按拖动逻辑代码

/**
 * Created on 2022/3/19 14:27
 *
 * @author Gong Youqiang
 */
public class RecyItemTouchHelperCallback extends ItemTouchHelper.Callback {
    RecyclerView.Adapter mAdapter;
    boolean isSwipeEnable;
    boolean isFirstDragUnable;

    public RecyItemTouchHelperCallback(RecyclerView.Adapter adapter) {
        mAdapter = adapter;
        isSwipeEnable = true;
        isFirstDragUnable = false;
    }

    public RecyItemTouchHelperCallback(RecyclerView.Adapter adapter, boolean isSwipeEnable, boolean isFirstDragUnable) {
        mAdapter = adapter;
        this.isSwipeEnable = isSwipeEnable;
        this.isFirstDragUnable = isFirstDragUnable;
    }

    @Override
    public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        if (recyclerView.getLayoutManager() instanceof GridLayoutManager) {
            int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN |
                    ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;
            int swipeFlags = 0;
            return makeMovementFlags(dragFlags, swipeFlags);
        } else {
            int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
            int swipeFlags = ItemTouchHelper.START | ItemTouchHelper.END;
            return makeMovementFlags(dragFlags, swipeFlags);
        }
    }

    @Override
    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
        int fromPosition = viewHolder.getAdapterPosition();
        int toPosition = target.getAdapterPosition();
        if (isFirstDragUnable && toPosition == 0) {
            return false;
        }
        if (fromPosition