android5.0自带兼容控件__RecyclerView

2021-08-26 11:07:53

RecyclerView

本文由 Luzhuo 编写,请尊重个人劳动成果,转发请保留该信息.
原文: http://blog.csdn.net/Rozol/article/details/50225593
微博: http://weibo.com/u/2524456400

RecyclerView是ListView和GridView的代替者.
RecyclerView有一套自己的回收规则,不再需要自己手动写代码去回收.

基本使用

基本代码:

XML布局:

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

Activity代码:

public class RecyclerViewDemo extends Activity {
    private RecyclerView recycle;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_recycleview);
        initView();
        initData();
    }

    private void initView() {
        recycle = (RecyclerView) findViewById(R.id.recycle);
    }

    private void initData() {
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        layoutManager.setOrientation(RecyclerView.VERTICAL);
        recycle.setLayoutManager(layoutManager);
        recycle.setAdapter(new RecycleAdapter(this));
    }
}

Adapter代码:

public class RecycleAdapter extends RecyclerView.Adapter<ViewHolder>{
    String[] contents = new String[]{"纵向列表","横向列表","纵向网格","横向网格","纵向瀑布流","横向瀑布流"};
    private Context context;

    public RecycleAdapter(Context context) {
        this.context = context;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.item_recycle_menu, parent, false);
        return new RecyclerHolder(view);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        ((RecyclerHolder) holder).setData(position);
    }

    @Override
    public int getItemCount() {
        return contents.length;
    }

    class RecyclerHolder extends RecyclerView.ViewHolder{
        private TextView content;

        public RecyclerHolder(View itemView) {
            super(itemView);
            content = (TextView) itemView.findViewById(R.id.content);
        }

        public void setData(int position) {
            content.setText(contents[position]);
        }
    }
}

效果:
android5.0自带兼容控件__RecyclerView

你所看到的长方格是子条目的CardView控件,RecyclerView默认没有分隔线.

不管是想实现ListView/GridView/瀑布流,基本代码不变,你只需要改写layoutManager的孩子就可实现ListView(LinearLayoutManager)/GridView(GridLayoutManager)/瀑布流(StaggeredGridLayoutManager).

源码研究

Code方法研究:

public class RecyclerView extends ViewGroup implements ScrollingView, NestedScrollingChild {
    public static final int HORIZONTAL = 0;
    public static final int VERTICAL = 1;
    public static final int NO_POSITION = -1;
    public static final long NO_ID = -1;
    public static final int INVALID_TYPE = -1;
    public static final int TOUCH_SLOP_DEFAULT = 0;
    public static final int TOUCH_SLOP_PAGING = 1;
    public static final int SCROLL_STATE_IDLE = 0;
    public static final int SCROLL_STATE_DRAGGING = 1;
    public static final int SCROLL_STATE_SETTLING = 2;

    public RecyclerViewAccessibilityDelegate getCompatAccessibilityDelegate() { }
    public void setAccessibilityDelegateCompat(RecyclerViewAccessibilityDelegate accessibilityDelegate) { } //XXX未知XXX
    public void setHasFixedSize(boolean hasFixedSize) { } //true:不允许Adapter改变RecyclerView的大小 {重要}
    public boolean hasFixedSize() { }
    public void setScrollingTouchSlop(int slopConstant) { } //设置touch越界 [TOUCH_SLOP_DEFAULT/TOUCH_SLOP_PAGING]
    public void swapAdapter(Adapter adapter, boolean removeAndRecycleExistingViews) { } // 更换Adapter
    public void setAdapter(Adapter adapter) { } // 更换Adapter
    public Adapter getAdapter() { }
    public void setRecyclerListener(RecyclerListener listener) { } // 设置回收监听
    public void addOnChildAttachStateChangeListener(OnChildAttachStateChangeListener listener) { } // 监听孩子的关联和脱离
    public void removeOnChildAttachStateChangeListener(OnChildAttachStateChangeListener listener) { }
    public void clearOnChildAttachStateChangeListeners() { }
    public void setLayoutManager(LayoutManager layout) { } // 设置布局管理者{重要}
    public LayoutManager getLayoutManager() { }
    public RecycledViewPool getRecycledViewPool() { }
    public void setRecycledViewPool(RecycledViewPool pool) { } // 设置回收池
    public void setViewCacheExtension(ViewCacheExtension extension) { } // 扩张缓存/null清除现有缓存
    public void setItemViewCacheSize(int size) { } // 设置条目缓存大小,这些条目不做任何修改直接使用
    public int getScrollState() { } //获取滚动状态 [SCROLL_STATE_IDLE/SCROLL_STATE_DRAGGING/SCROLL_STATE_SETTLING] {重要}
    public void addItemDecoration(ItemDecoration decor, int index) { } // 添加条目的装饰
    public void addItemDecoration(ItemDecoration decor) { }
    public void removeItemDecoration(ItemDecoration decor) { }
    public void setChildDrawingOrderCallback(ChildDrawingOrderCallback childDrawingOrderCallback) { } //设置孩子绘画回调
    public void addOnScrollListener(OnScrollListener listener) { } // 添加滚动监听 {重要}
    public void removeOnScrollListener(OnScrollListener listener) { } // {重要}
    public void clearOnScrollListeners() { }
    public void scrollToPosition(int position) { } // 滚动到某个位置 {重要}
    public void smoothScrollToPosition(int position) { } // 平滑的滚动到某个位置 {重要}
    public void setLayoutFrozen(boolean frozen) { } // true:冻结布局和滚动; false:释放冻结 (冻结后仍可调用scrollToPosition/smoothScrollToPosition) {重要}
    public boolean isLayoutFrozen() { }
    public void smoothScrollBy(int dx, int dy) { }
    public boolean fling(int velocityX, int velocityY) { } // true:在抛(速度快) {重要}
    public void stopScroll() { } // 停止滚动
    public int getMinFlingVelocity() { } // 最小的抛速度
    public int getMaxFlingVelocity() { }
    public void addOnItemTouchListener(OnItemTouchListener listener) { } // 添加条目touch监听
    public void removeOnItemTouchListener(OnItemTouchListener listener) { }
    public boolean isComputingLayout() { } // true:是现在在处理的布局
    public ItemAnimator getItemAnimator() { } // 条目动画/null:没有动画
    public boolean isAnimating() { }
    public void invalidateItemDecorations() { } // 刷新条目装饰
    public ViewHolder getChildViewHolder(View child) { } // 获取孩子的ViewHolder
    public int getChildAdapterPosition(View child) { } //孩子在适配器中的位置
    public int getChildLayoutPosition(View child) { }
    public long getChildItemId(View child) { } // 获取条目id
    public ViewHolder findViewHolderForLayoutPosition(int position) { }
    public ViewHolder findViewHolderForAdapterPosition(int position) { }
    public ViewHolder findViewHolderForItemId(long id) { }
    public View findChildViewUnder(float x, float y) { } //给定的点下找到的最上面的子view
    public void offsetChildrenVertical(int dy) { } // 垂直滚动
    public void onChildAttachedToWindow(View child) { }
    public void onChildDetachedFromWindow(View child) { }
    public void offsetChildrenHorizontal(int dx) { } // 水平滚动
    public boolean hasPendingAdapterUpdates() { } // 是否有未更新的布局

    public static class RecycledViewPool { } // 回收池
    public static abstract class Adapter<VH extends ViewHolder> { } // 适配器 {重要}
    public static abstract class LayoutManager { } // 布局管理 {重要}
    public static abstract class ItemDecoration {}
    public static class SimpleOnItemTouchListener implements RecyclerView.OnItemTouchListener { }
    public static abstract class ViewHolder { } // ViewHolder {重要}
    public static class LayoutParams extends android.view.ViewGroup.MarginLayoutParams { } //LayoutParams
    public static abstract class AdapterDataObserver { } // 观察者
    public static abstract class SmoothScroller { } // 滚动类 {重要}
    static class AdapterDataObservable extends Observable<AdapterDataObserver> { } // 观察者
    public static class State {}
    public static abstract class ItemAnimator { } // 条目动画类 {重要}
}

从源码的方法上可以看出,RecyclerView与传统的ListView还是有些区别的:

RecyclerView没有了对孩子的onClick的监听方法;

想要实现点击监听其实很简单,你只需要在控件上实现点击监听后,然后把事件通过接口传递给外面调用.
参考代码:
public class RecyclerHolder extends RecyclerView.ViewHolder implements OnClickListener{
public TextView content;
public int position;
private CardView cardview;
public RecyclerHolder(View itemView) {
    super(itemView);
    content = (TextView) itemView.findViewById(R.id.item_content);
    cardview = (CardView) itemView.findViewById(R.id.item_cardview);
    cardview.setOnClickListener(this);
}

public void setData(int position) {
    this.position = position;
    content.setText(contents[position]);
}

@Override
public void onClick(View v) {
    if(onItemClickListener != null) onItemClickListener.onItemClick(this, position);
}
}

public void setOnItemClickListener(OnItemClickListener onItemClickListener){
this.onItemClickListener = onItemClickListener;
}

public static interface OnItemClickListener {
void onItemClick(RecyclerHolder recyclerHolder, int position);
}
效果: