RecyclerView之初体验 - - !

好久没回归我原生大Android开发啦！甚是怀念啊！终于，公司最近来了一个原生项目，可以好好爽一把了！实不相瞒，我现在写列表还是用的ListView - -！想想以前用的那些东西，是该换换了！早就想用RecyclerView了，一直没机会！哎~~~网络框架就看了一下OkGo。然后！！大换血！！！

这回闲下来了，好好学一学RecyclerView的基本使用了，先能实现个普通列表开发就行！哈哈~~~

使用RecyclerView的好处，想必你们这些大佬早就一清二楚了！我也查了相关帖子，也就不赘述了！

初始化

        recyclerView = findViewById(R.id.recyclerView);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
//        recyclerView.setLayoutManager(new GridLayoutManager(this, 2));
        recyclerView.addItemDecoration(new ItemDecoration(this, R.drawable.divider_line, 1));
        adapter = new MyAdapter(this);
        adapter.openLoadAnimation();
//        adapter.isFirstOnly(false);

        recyclerView.setAdapter(adapter);

这里的adapter，我用了一个库，叫BRVAH，GitHub上一搜就能找到，start也很高~~ 从此，妈妈再也不用担心我写adapter了！

public class MyAdapter extends BaseQuickAdapter<ClassListBean.DataBean, BaseViewHolder> {
    private Context context;

    public MyAdapter(Context context) {
        super(R.layout.item);
        this.context = context;
    }

    @Override
    protected void convert(BaseViewHolder helper, ClassListBean.DataBean item) {

//        helper.setGone(R.id.tv_mirror, helper.getLayoutPosition() - getHeaderLayoutCount() == 0);

        Picasso.with(context).load(item.getPicBig()).into((ImageView) helper.getView(R.id.iv_avatar));
        helper.setText(R.id.tv_title, item.getName());
        helper.setText(R.id.tv_desc, item.getDescription());
        helper.setText(R.id.tv_num, "当前学员数：" + item.getLearner());
        helper.addOnClickListener(R.id.iv_avatar).addOnClickListener(R.id.tv_title);
    }
}

用了这个库，写个adapter，简直不要太粗暴！几行就搞定！！而且这个库还有更高级的用法，大佬们自行去看吧！

用了RecyclerView，唯独的一点弱地方，就是分割线和item的点击事件了！

先说点击事件，上面这个库已经完美解决了！

        //普通点击事件
        adapter.setOnItemClickListener(new BaseQuickAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(BaseQuickAdapter adapter, View view, int position) {
                showToast(position + "");
            }
        });
        //子view点击事件
        adapter.setOnItemChildClickListener(new BaseQuickAdapter.OnItemChildClickListener() {
            @Override
            public void onItemChildClick(BaseQuickAdapter adapter, View view, int position) {
                ClassListBean.DataBean b = (ClassListBean.DataBean) adapter.getItem(position);
                switch (view.getId()) {
                    case R.id.iv_avatar:
                        showToast(b.getPicBig());
                        break;
                    case R.id.tv_title:
                        showToast(b.getName());
                        break;
                }
            }
        });

再说分割线！话不多说，放类！


/**
 * RecyclerView分割线(适用于纵向列表和网格布局，横向列表忽略)
 */
public class ItemDecoration extends RecyclerView.ItemDecoration {
    private Drawable mDivider;
    private int style;

    /**
     * resId自定义，style  1:垂直列表分割线  2：网格布局分割线
     */
    public ItemDecoration(Context context, int resId, int style) {
        mDivider = context.getResources().getDrawable(resId);
        this.style = style;
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        if (style == 1) {
            drawListVertical(c, parent);
        }
        if (style == 2) {
            drawHorizontal(c, parent);
            drawGridVertical(c, parent);
        }
    }

    private int getSpanCount(RecyclerView parent) {
        int spanCount = -1;// 列数
        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {
            spanCount = ((GridLayoutManager) layoutManager).getSpanCount();
        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
            spanCount = ((StaggeredGridLayoutManager) layoutManager).getSpanCount();
        }
        return spanCount;
    }

    public void drawListVertical(Canvas c, RecyclerView parent) {
        int left = parent.getPaddingLeft();
        int right = parent.getWidth() - parent.getPaddingRight();
        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
//            if (i == childCount - 1) {//最后一项底部是否设置线，显示这一块代码就不设置
//                return;
//            }
            View child = parent.getChildAt(i);
            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            int top = child.getBottom() + params.bottomMargin;
            int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    public void drawHorizontal(Canvas c, RecyclerView parent) {
        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);
            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            int top = parent.getChildAt(i).getTop() - mDivider.getIntrinsicHeight();
            int bottom = parent.getChildAt(i).getBottom();
            int left = child.getRight() + params.leftMargin;
            int right = left + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    public void drawGridVertical(Canvas c, RecyclerView parent) {
        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);
            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            int left = parent.getChildAt(i).getLeft() + params.leftMargin;
            int right = parent.getChildAt(i).getRight() + params.rightMargin;
            int top = child.getBottom() + params.bottomMargin;
            int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    private boolean isLastColum(RecyclerView parent, int pos, int spanCount, int childCount) {
        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {
            if ((pos + 1) % spanCount == 0) {// 如果是最后一列，则不需要绘制右边
                return true;
            }
        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
            int orientation = ((StaggeredGridLayoutManager) layoutManager).getOrientation();
            if (orientation == StaggeredGridLayoutManager.VERTICAL) {
                if ((pos + 1) % spanCount == 0) {// 如果是最后一列，则不需要绘制右边
                    return true;
                }
            } else {
                childCount = childCount - childCount % spanCount;
                if (pos >= childCount)// 如果是最后一列，则不需要绘制右边
                    return true;
            }
        }
        return false;
    }

    private boolean isLastRaw(RecyclerView parent, int pos, int spanCount, int childCount) {
        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {
            childCount = childCount - childCount % spanCount;
            if (pos >= childCount)// 如果是最后一行，则不需要绘制底部
                return true;
        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
            int orientation = ((StaggeredGridLayoutManager) layoutManager).getOrientation();
            // StaggeredGridLayoutManager 且纵向滚动
            if (orientation == StaggeredGridLayoutManager.VERTICAL) {
                childCount = childCount - childCount % spanCount;
                // 如果是最后一行，则不需要绘制底部
                if (pos >= childCount)
                    return true;
            } else {
                // StaggeredGridLayoutManager 且横向滚动
                // 如果是最后一行，则不需要绘制底部
                if ((pos + 1) % spanCount == 0) {
                    return true;
                }
            }
        }
        return false;
    }

    @Override
    public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
        int spanCount = getSpanCount(parent);
        int childCount = parent.getAdapter().getItemCount();
        if (isLastRaw(parent, itemPosition, spanCount, childCount)) {// 如果是最后一行，则不需要绘制底部
            outRect.set(0, 0, mDivider.getIntrinsicHeight(), 0);
        } else if (isLastColum(parent, itemPosition, spanCount, childCount)) {// 如果是最后一列，则不需要绘制右边
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicHeight(), mDivider.getIntrinsicHeight());
        }
    }
}

在初始化的地方，我已经设置了分割线，分割线的样式，可以自己定义：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <solid android:color="#ccc"/>
    <size android:height="1px"/>
</shape>

OK！完事！睡觉！！！

RecyclerView之初体验 - - !

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