RecyclerView作為L(zhǎng)istView,GridView的升級(jí)版，使用起來(lái)非常靈活。并且配合動(dòng)畫(huà)可以實(shí)現(xiàn)非常贊的效果。
基本使用步驟:
mRecyclerView = findView(R.id.id_recyclerview);
//設(shè)置布局管理器
mRecyclerView.setLayoutManager(layout);
//設(shè)置adapter
mRecyclerView.setAdapter(adapter)
//設(shè)置Item增加、移除動(dòng)畫(huà)
mRecyclerView.setItemAnimator(new DefaultItemAnimator());
//添加分割線(xiàn)
mRecyclerView.addItemDecoration(new DividerItemDecoration(
getActivity(), DividerItemDecoration.HORIZONTAL_LIST));
1.基礎(chǔ)知識(shí)點(diǎn)
- LayoutManager 顧名思義 負(fù)責(zé)布局的管理，通過(guò)切換布局管理器我們可以輕松實(shí)現(xiàn)列表，網(wǎng)格，瀑布流等效果。
- Adapter 用于適配item,這里的Adapter是繼承自RecyclerView.Adapter不是BaseAdapter
- ItemDecoration 通俗點(diǎn)講就是“分割線(xiàn)”，類(lèi)似listView中的divider，但是RecyclerView中并未提供這個(gè)屬性，要實(shí)現(xiàn)分割線(xiàn)，需要通過(guò)調(diào)用addItemDecoration()，系統(tǒng)并未提供缺省的ItemDecoration實(shí)現(xiàn)類(lèi)。幸運(yùn)的是已經(jīng)有第三方實(shí)現(xiàn)好了的ItemDecoration，后面介紹
- ItemAnimator 有了它可以實(shí)現(xiàn)各種炫酷的動(dòng)畫(huà)效果，系統(tǒng)提供了缺省的DefaultItemAnimator
2.知識(shí)點(diǎn)詳解
⑴ LayoutManager 系統(tǒng)提供了LinearLayoutManager，GridLayoutManager，StaggeredGridLayoutManager,分別對(duì)應(yīng)三種效果 列表，網(wǎng)格，瀑布流。示例代碼：
mNormalRecyclerView.setLayoutManager(new LinearLayoutManager(this));//設(shè)置list布局
mNormalRecyclerView.setLayoutManager(new GridLayoutManager(this, 4));//設(shè)置網(wǎng)格布局
mNormalRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL));//設(shè)置瀑布流布局
可以看到想要切換效果只需要設(shè)置下LayoutManager，對(duì)于有需求要求顯示多種布局效果的時(shí)候，用RecyclerView相比listView等要省力靈活很多。
...
也許這還不夠打動(dòng)你，接著往下看
通常我們的listView，GirdView都是豎直方向流向的，需求來(lái)了要實(shí)現(xiàn)橫向的listView腫么辦？過(guò)去還是要花點(diǎn)力氣去實(shí)現(xiàn)的吧，看RecyclerView分分鐘秒殺你
LinearLayoutManager layoutManager=new LinearLayoutManager(this);
layoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
mNormalRecyclerView.setLayoutManager(layoutManager);//設(shè)置list橫向布局
⑵ Adapter 適配item布局的東東看代碼，先寫(xiě)個(gè)最簡(jiǎn)單的Adapter
public class AdapterNormal extends RecyclerView.Adapter<AdapterNormal.MyViewHolder> {
private Context context;
private List<String> list;
public AdapterNormal(Context context, List<String> list) {
this.context = context;
this.list = list;
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {//產(chǎn)生幾個(gè)可復(fù)用的ViewHolder實(shí)例
MyViewHolder viewHolder = new MyViewHolder(LayoutInflater.from(context).inflate(R.layout.adapter_item, parent, false));
return viewHolder;
}
@Override
public int getItemCount() {
return list.size();
}
@Override
public void onBindViewHolder(final MyViewHolder holder, final int position) {//為每一項(xiàng)View綁定數(shù)據(jù)
holder.mTextView.setText(list.get(position));
}
class MyViewHolder extends RecyclerView.ViewHolder {//ViewHolder 大家都不陌生
private TextView mTextView;
public MyViewHolder(View itemView) {
super(itemView);
mTextView = (TextView) itemView.findViewById(R.id.mText);
}
}
}
調(diào)用它
adapterNormal = new AdapterNormal(getApplicationContext(), list);
mNormalRecyclerView.setAdapter(adapterNormal);//設(shè)置適配器
多個(gè)不同項(xiàng)布局，Adapter該怎么寫(xiě)？
@Override
public int getItemViewType(int position) {//在Adapter中重寫(xiě)該方法，根據(jù)條件返回不同的值例如100,101
if (...) {
return 100;
}else if (...) {
return 101;
}else{
return super.getItemViewType(position);
}
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {//根據(jù)getItemViewType返回的值生成不同的ViewHolder實(shí)例
MyViewHolder viewHolder = null;
switch (viewType) {//示例邏輯
case 100:
viewHolder=...;
break;
case 101:
viewHolder=...;
break;
default:
viewHolder = new MyViewHolder(LayoutInflater.from(context).inflate(R.layout.adapter_item, parent, false));
break;
}
return viewHolder;
}
@Override
public void onBindViewHolder(final MyViewHolder holder, final int position) {//為不同的布局適配數(shù)據(jù)
switch (holder.getItemViewType()) {
case 100:
...
break;
case 101:
...
break;
default:
holder.mTextView.setText(list.get(position));
break;
}
}
每次都這樣寫(xiě)Adapter是不是覺(jué)得很累？簡(jiǎn)化它
首先引入 compile 'com.zhy:base-adapter:2.0.0'
Android 萬(wàn)能的Adapter for ListView,RecyclerView,GridView等，支持多種Item類(lèi)型的情況。
mRecyclerView.setAdapter(new CommonAdapter<String>(this, R.layout.item_list, mDatas)
{
@Override
public void convert(ViewHolder holder, String s)
{
holder.setText(R.id.id_item_list_title, s);
}
});
是不是相當(dāng)方便，在convert方法中完成數(shù)據(jù)、事件綁定即可。還有多種ItemViewType的封裝等自行研究都很方便
⑶ItemDecoration "分割線(xiàn)" 這玩意感覺(jué)沒(méi)什么好說(shuō)的直接看代碼
/**
* ListView的分割線(xiàn)
*/
public class ListItemDecoration extends RecyclerView.ItemDecoration {
private static final int[] ATTRS = new int[]{
android.R.attr.listDivider
};
public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;
public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;
private Drawable mDivider;
private int mOrientation;
public ListItemDecoration(Context context, int orientation) {
final TypedArray a = context.obtainStyledAttributes(ATTRS);
mDivider = a.getDrawable(0);
a.recycle();
setOrientation(orientation);
}
public void setOrientation(int orientation) {
if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
throw new IllegalArgumentException("invalid orientation");
}
mOrientation = orientation;
}
@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
if (mOrientation == VERTICAL_LIST) {
drawVertical(c, parent);
} else {
drawHorizontal(c, parent);
}
}
public void drawVertical(Canvas c, RecyclerView parent) {
final int left = parent.getPaddingLeft();
final int right = parent.getWidth() - parent.getPaddingRight();
final int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = parent.getChildAt(i);
android.support.v7.widget.RecyclerView v = new android.support.v7.widget.RecyclerView(parent.getContext());
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
.getLayoutParams();
final int top = child.getBottom() + params.bottomMargin;
final int bottom = top + mDivider.getIntrinsicHeight();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}
public void drawHorizontal(Canvas c, RecyclerView parent) {
final int top = parent.getPaddingTop();
final int bottom = parent.getHeight() - parent.getPaddingBottom();
final int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = parent.getChildAt(i);
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
.getLayoutParams();
final int left = child.getRight() + params.rightMargin;
final int right = left + mDivider.getIntrinsicHeight();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
if (mOrientation == VERTICAL_LIST) {
outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
} else {
outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
}
}
}
/**
* @author 鴻洋
* GridView的分割線(xiàn)
* 因?yàn)樽髡咂俨剂鞯姆指罹€(xiàn)在item高度不一樣的情況下有bug，所以被我去掉了
*/
public class GridItemDecoration extends RecyclerView.ItemDecoration {
private static final int[] ATTRS = new int[]{android.R.attr.listDivider};
private Drawable mDivider;
public GridItemDecoration(Context context) {
final TypedArray a = context.obtainStyledAttributes(ATTRS);
mDivider = a.getDrawable(0);
a.recycle();
}
@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
drawHorizontal(c, parent);
drawVertical(c, parent);
}
private int getSpanCount(RecyclerView parent) {
// 列數(shù)
int spanCount = -1;
RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
spanCount = ((GridLayoutManager) layoutManager).getSpanCount();
return spanCount;
}
public void drawHorizontal(Canvas c, RecyclerView parent) {
int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = parent.getChildAt(i);
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
.getLayoutParams();
final int left = child.getLeft() - params.leftMargin;
final int right = child.getRight() + params.rightMargin
+ mDivider.getIntrinsicWidth();
final int top = child.getBottom() + params.bottomMargin;
final int bottom = top + mDivider.getIntrinsicHeight();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}
public void drawVertical(Canvas c, RecyclerView parent) {
final int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = parent.getChildAt(i);
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
.getLayoutParams();
final int top = child.getTop() - params.topMargin;
final int bottom = child.getBottom() + params.bottomMargin;
final int left = child.getRight() + params.rightMargin;
final int right = left + mDivider.getIntrinsicWidth();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}
private boolean isLastColum(int pos, int spanCount) {
if ((pos + 1) % spanCount == 0)// 如果是最后一列，則不需要繪制右邊
{
return true;
}
return false;
}
private boolean isLastRaw(int pos, int spanCount, int childCount) {
childCount = childCount - childCount % spanCount;
if (pos >= childCount)// 如果是最后一行，則不需要繪制底部
return true;
return false;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
int spanCount = getSpanCount(parent);
int childCount = parent.getAdapter().getItemCount();
if (isLastRaw(parent.getChildAdapterPosition(view), spanCount, childCount))// 如果是最后一行，則不需要繪制底部
{
outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
} else if (isLastColum(parent.getChildAdapterPosition(view), spanCount))// 如果是最后一列，則不需要繪制右邊
{
outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
} else {
outRect.set(0, 0, mDivider.getIntrinsicWidth(),
mDivider.getIntrinsicHeight());
}
}
}
⑷ ItemAnimator 前面說(shuō)過(guò)了可以產(chǎn)生炫酷的動(dòng)畫(huà)，提升逼格的神器
https://github.com/wasabeef/recyclerview-animators
demo3.gif
demo2.gif
demo.gif
⑸ “遺憾”。 是的RecyclerView并沒(méi)有像listView,GridView那樣提供itemClickListener和itemLongClickListener，我們需要自行實(shí)現(xiàn)，可以通過(guò)設(shè)置接口回調(diào)，好消息是上面提到的Android 萬(wàn)能的Adapter 已經(jīng)為我們實(shí)現(xiàn)好了這些工作。
⑹ 補(bǔ)充。當(dāng)數(shù)據(jù)發(fā)生變化時(shí)我們需要更新數(shù)據(jù)集
adapterNormal.notifyDataSetChanged(); //無(wú)動(dòng)畫(huà)效果
adapterNormal.notifyItemInserted(0);//有動(dòng)畫(huà)效果
以上就是RecyclerView的基本使用，華麗的分割線(xiàn)，提升。。。
自定義RecyclerView，實(shí)現(xiàn)下拉刷新，上拉加載更多
https://github.com/jianghejie/XRecyclerView
看效果先
default.gif
源碼淺析：
public class XRecyclerView extends RecyclerView {
@Override
public void setAdapter(Adapter adapter) {//重寫(xiě)適配器方法
mWrapAdapter = new WrapAdapter(adapter);//一個(gè)包裝類(lèi)
super.setAdapter(mWrapAdapter);//設(shè)置這個(gè)包裝后的適配器作為適配器
adapter.registerAdapterDataObserver(mDataObserver);//注冊(cè)自定義的數(shù)據(jù)觀察者，因?yàn)檫m配器是包裝后的適配器
mDataObserver.onChanged();
}
@Override
public void onScrollStateChanged(int state) {//通過(guò)判斷最后一個(gè)可見(jiàn)item的位置和項(xiàng)數(shù)量的大小關(guān)系實(shí)現(xiàn)上拉加載更多
super.onScrollStateChanged(state);
if (state == RecyclerView.SCROLL_STATE_IDLE && mLoadingListener != null && !isLoadingData && loadingMoreEnabled) {
LayoutManager layoutManager = getLayoutManager();
int lastVisibleItemPosition;
if (layoutManager instanceof GridLayoutManager) {
lastVisibleItemPosition = ((GridLayoutManager) layoutManager).findLastVisibleItemPosition();
} else if (layoutManager instanceof StaggeredGridLayoutManager) {
int[] into = new int[((StaggeredGridLayoutManager) layoutManager).getSpanCount()];
((StaggeredGridLayoutManager) layoutManager).findLastVisibleItemPositions(into);
lastVisibleItemPosition = findMax(into);
} else {
lastVisibleItemPosition = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();
}
if (layoutManager.getChildCount() > 0
&& lastVisibleItemPosition >= layoutManager.getItemCount() - 1 && layoutManager.getItemCount() > layoutManager.getChildCount() && !isNoMore && mRefreshHeader.getState() < ArrowRefreshHeader.STATE_REFRESHING) {
View footView = mFootViews.get(0);
isLoadingData = true;
if (footView instanceof LoadingMoreFooter) {
((LoadingMoreFooter) footView).setState(LoadingMoreFooter.STATE_LOADING);
} else {
footView.setVisibility(View.VISIBLE);
}
mLoadingListener.onLoadMore();
}
}
}
@Override
public boolean onTouchEvent(MotionEvent ev) {//通過(guò)重寫(xiě)觸摸事件實(shí)現(xiàn)下拉刷新
if (mLastY == -1) {
mLastY = ev.getRawY();
}
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
mLastY = ev.getRawY();
break;
case MotionEvent.ACTION_MOVE:
final float deltaY = ev.getRawY() - mLastY;
mLastY = ev.getRawY();
if (isOnTop() && pullRefreshEnabled) {
mRefreshHeader.onMove(deltaY / DRAG_RATE);
if (mRefreshHeader.getVisibleHeight() > 0 && mRefreshHeader.getState() < ArrowRefreshHeader.STATE_REFRESHING) {
return false;
}
}
break;
default:
mLastY = -1; // reset
if (isOnTop() && pullRefreshEnabled) {
if (mRefreshHeader.releaseAction()) {
if (mLoadingListener != null) {
mLoadingListener.onRefresh();
}
}
}
break;
}
return super.onTouchEvent(ev);
}
}
private class WrapAdapter extends RecyclerView.Adapter<ViewHolder> {//定義一個(gè)包裝類(lèi)，將外部自定義的適配器和內(nèi)部適配器邏輯關(guān)聯(lián)起來(lái)
private RecyclerView.Adapter adapter;//持有我們使用的時(shí)候自定義的適配器
public WrapAdapter(RecyclerView.Adapter adapter) {
this.adapter = adapter;
}
@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {//只執(zhí)行一次
super.onAttachedToRecyclerView(recyclerView);
RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();
if (manager instanceof GridLayoutManager) {
final GridLayoutManager gridManager = ((GridLayoutManager) manager);
gridManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {//設(shè)置監(jiān)聽(tīng)回調(diào)只需要設(shè)置一次
@Override
public int getSpanSize(int position) {//SpanSize 代表占幾列
return (isHeader(position) || isFooter(position))//頭部或者尾部占滿(mǎn)全行或者全列
? gridManager.getSpanCount() : 1;
}
});
}
}
@Override
public void onViewAttachedToWindow(RecyclerView.ViewHolder holder) {//被多次調(diào)用
super.onViewAttachedToWindow(holder);
ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();
if (lp != null
&& lp instanceof StaggeredGridLayoutManager.LayoutParams
&& (isHeader(holder.getLayoutPosition()) || isFooter(holder.getLayoutPosition()))) {
StaggeredGridLayoutManager.LayoutParams p = (StaggeredGridLayoutManager.LayoutParams) lp;
p.setFullSpan(true);//頭部或者尾部占滿(mǎn)全行或者全列
}
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == TYPE_REFRESH_HEADER) {//根據(jù)返回的類(lèi)型生成不同的ViewHolder實(shí)例
mCurrentPosition++;
return new SimpleViewHolder(mHeaderViews.get(0));
} else if (isContentHeader(mCurrentPosition)) {
if (viewType == sHeaderTypes.get(mCurrentPosition - 1)) {
mCurrentPosition++;
return new SimpleViewHolder(mHeaderViews.get(headerPosition++));
}
} else if (viewType == TYPE_FOOTER) {
return new SimpleViewHolder(mFootViews.get(0));
}
return adapter.onCreateViewHolder(parent, viewType);
}
private int mCurrentPosition;
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {//為我們自定義的item類(lèi)型綁定數(shù)據(jù)
if (isHeader(position)) {
return;
}
int adjPosition = position - getHeadersCount();
int adapterCount;
if (adapter != null) {
adapterCount = adapter.getItemCount();
if (adjPosition < adapterCount) {
adapter.onBindViewHolder(holder, adjPosition);
return;
}
}
}
@Override
public int getItemViewType(int position) {//返回刷新頭類(lèi)型，普通頭類(lèi)型，尾部類(lèi)型，我們自定義的類(lèi)型
if (isRefreshHeader(position)) {
return TYPE_REFRESH_HEADER;
}
if (isHeader(position)) {
position = position - 1;
return sHeaderTypes.get(position);
}
if (isFooter(position)) {
return TYPE_FOOTER;
}
int adjPosition = position - getHeadersCount();
int adapterCount;
if (adapter != null) {
adapterCount = adapter.getItemCount();
if (adjPosition < adapterCount) {
return adapter.getItemViewType(adjPosition);
}
}
return TYPE_NORMAL;
}
}
private class DataObserver extends RecyclerView.AdapterDataObserver {
@Override
public void onChanged() {//數(shù)據(jù)改變的時(shí)候通過(guò)比較item數(shù)量顯示隱藏EmptyView
Adapter<?> adapter = getAdapter();
if (adapter != null && mEmptyView != null) {
int emptyCount = 0;
if (pullRefreshEnabled) {
emptyCount++;
}
if (loadingMoreEnabled) {
emptyCount++;
}
if (adapter.getItemCount() == emptyCount) {
mEmptyView.setVisibility(View.VISIBLE);
XRecyclerView.this.setVisibility(View.GONE);
} else {
mEmptyView.setVisibility(View.GONE);
XRecyclerView.this.setVisibility(View.VISIBLE);
}
}
if (mWrapAdapter != null) {
mWrapAdapter.notifyDataSetChanged();
}
}
@Override
public void onItemRangeInserted(int positionStart, int itemCount) {
mWrapAdapter.notifyItemRangeInserted(positionStart, itemCount);
}
@Override
public void onItemRangeChanged(int positionStart, int itemCount) {
mWrapAdapter.notifyItemRangeChanged(positionStart, itemCount);
}
@Override
public void onItemRangeChanged(int positionStart, int itemCount, Object payload) {
mWrapAdapter.notifyItemRangeChanged(positionStart, itemCount, payload);
}
@Override
public void onItemRangeRemoved(int positionStart, int itemCount) {
mWrapAdapter.notifyItemRangeRemoved(positionStart, itemCount);
}
@Override
public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {
mWrapAdapter.notifyItemMoved(fromPosition, toPosition);
}
};
大致思路：定義一個(gè)包裝適配器，通過(guò)不同的item類(lèi)型判斷生成刷新頭，普通頭部，尾部，我們自定義的itemView并綁定item數(shù)據(jù)→監(jiān)聽(tīng)滾動(dòng)和觸摸事件來(lái)顯示隱藏刷新頭和加載更多尾部視圖并通過(guò)接口拋出刷新和加載更多抽象方法
