編輯：關於android開發
這篇文章應該是晚到了好幾個月，之前想寫，但是中途遇到了一些棘手的問題，無奈沒有去寫。寫這篇文章的最初來源是一個朋友問我在Android中如何實現瀑布流布局？，當時我的回答是使用RecyclerView，後來他又問我那怎麼實現上拉加載並添加Footer呢？我想都沒想就回答他根據type的不同去添加一個Footer，監聽滾動事件，當滑動到最後顯示footer並回調對應的接口，那麼，這個過程就會遇到一個Footer布局顯示的問題，就像下面這張圖一樣。
![瀑布流布局](https://www.android5.online/Android/UploadFiles_5356/201603/2016031509365192.jpg "\")
可以看到，我們 的 Footer布局並沒有占據全屏，而是作為瀑布流布局的一部分了。這顯然不是我們想要的。
當然，除了為瀑布流布局添加Footer實現上拉加載外，我們還想要對GridLayout添加Footer實現上拉加載，同樣的，在GridLayout中，布局也不是我們想要的結果。效果也是這樣。<喎?http://www.Bkjia.com/kf/ware/vc/" target="_blank" class="keylink">vcD4NCjxwPjxpbWcgYWx0PQ=="網格布局" src="http://www.bkjia.com/uploads/allimg/151204/04191V356-1.jpg" title="\" />
也把我們的Footer作為了GridLayout的一部分，並沒有全屏進行顯示。
那麼接下來，我們需要解決幾個問題，即可以實現正確的添加Footer並實現上拉加載功能了。
如何實現上拉加載更多？這個解決方法很簡單，就是為RecyclerView添加滾動監聽事件，根據布局的不同編寫對應的邏輯代碼，實現滑到到底部加載更多的功能。 如何正確的添加Footer，使其能夠占據寬度為全屏顯示？這個有點棘手，但是並不是不能解決，我們需要對適配器進行一些處理就能實現該功能。 此外我們還想要添加一個Header，用於展示ViewPager或者圖片等信息。這個原理和添加Footer是一樣的。首先定義一個處理上拉加載的接口
{
/**
* 加載更多前回調，比如顯示Footer的操作
*/
void onStart();
/**
* 加載更多業務處理，如網絡請求數據
*/
void onLoadMore();
/**
* 由於onLoadMore可能是異步調用的，所以onFinish需要手動調用，完成數據的刷新，隱藏Footer等
* @param list onLoadMore中返回的數據
*/
void onFinish(List list);
}
data-snippet-id=ext.cc07bacad0a477ab79bf37c7a4816d6c data-snippet-saved=false data-csrftoken=ZTMcU6vd-NgDp77SKpjjlkSUOG4bk4z3Haps data-codota-status=done>public interface OnLoadMoreListener {
/**
* 加載更多前回調，比如顯示Footer的操作
*/
void onStart();
/**
* 加載更多業務處理，如網絡請求數據
*/
void onLoadMore();
/**
* 由於onLoadMore可能是異步調用的，所以onFinish需要手動調用，完成數據的刷新，隱藏Footer等
* @param list onLoadMore中返回的數據
*/
void onFinish(List list);
}
然後我們自己定義一個抽象類，用於繼承RecyclerView.OnScrollListener並實現我們定義的接口OnLoadMoreListener，如果需要上拉加載更多，直接為RecyclerView添加滾動監聽為我們的實現類即可，就像這樣子
(){
@Override
public void onStart() {
}
@Override
public void onLoadMore() {
}
@Override
public void onFinish(List contents) {
}
}); data-snippet-id=ext.0844dddee4a714a4268444c38a586fc9 data-snippet-saved=false data-csrftoken=4LFZmucK-NSOMJIOwLJFxok_hrTLKo8Fn7k4 data-codota-status=done>mRecyclerView.addOnScrollListener(new OnRecyclerViewScrollListener(){
@Override
public void onStart() {
}
@Override
public void onLoadMore() {
}
@Override
public void onFinish(List contents) {
}
});
由於RecyclerView默認有三種布局，所以我們要對這三種布局分別進行判斷上拉加載，處理的邏輯有點不同，首先添加如下定義
extends RecyclerView.OnScrollListener implements OnLoadMoreListener{ public static enum layoutManagerType { LINEAR_LAYOUT, GRID_LAYOUT, STAGGERED_GRID_LAYOUT } protected layoutManagerType mLayoutManagerType; private boolean mIsLoadingMore = false; public boolean isLoadingMore() { return mIsLoadingMore; } public void setLoadingMore(boolean loadingMore) { mIsLoadingMore = loadingMore; } } data-snippet-id=ext.967dc8ab948ebc337a4f7395fe22dd9c data-snippet-saved=false data-csrftoken=wKKbaPlN-NACfZ3XMzeRxhcjoTme0vLqzs0A data-codota-status=done> public abstract class OnRecyclerViewScrollListenerextends RecyclerView.OnScrollListener implements OnLoadMoreListener { public static enum layoutManagerType { LINEAR_LAYOUT, GRID_LAYOUT, STAGGERED_GRID_LAYOUT } protected layoutManagerType mLayoutManagerType; private boolean mIsLoadingMore = false; public boolean isLoadingMore() { return mIsLoadingMore; } public void setLoadingMore(boolean loadingMore) { mIsLoadingMore = loadingMore; } }
這個類是泛型的，接收一個實現了Item接口的類。主要是定義了一個枚舉類，裡面是布局的類型，然後是一個布爾變量，用於判斷當前是否正在加載更多。
RecyclerViewAdapter.Item主要是一個接口，其定義如下
public interface Item {
int TYPE_HEADER = 0;
int TYPE_FOOTER = 1;
/**
* 返回item類型，其值不能為0或者1；
*
* @return
*/
int getType();
}
我們的RecyclerView的Item實體類需要實現Item接口，並返還item的類型，默認情況下header的類型為0，footer的類型為1。
接下來最重要的事就是實現onScrolled和onScrollStateChanged方法，根據布局的不同判斷是否需要加載更多操作。
0 && currentScrollState == RecyclerView.SCROLL_STATE_IDLE
&& lastVisibleItemPosition >= totalItemCount - 1) {
if (!isLoadingMore()){
mIsLoadingMore =true;
onStart();
onLoadMore();
}
}
}
private int findMax(int[] lastPositions) {
int max = lastPositions[0];
for (int value : lastPositions) {
if (value > max) {
max = value;
}
}
return max;
} data-snippet-id=ext.b411da8ce079e7d03088c032c7dbb07b data-snippet-saved=false data-csrftoken=ZfLZwkcC-e0C6W5TY9NiIB3-uEal0irNnhIY data-codota-status=done> private int[] lastPositions;
private int lastVisibleItemPosition;
private int currentScrollState = 0;
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
if (mLayoutManagerType == null) {
if (layoutManager instanceof LinearLayoutManager) {
mLayoutManagerType = layoutManagerType.LINEAR_LAYOUT;
} else if (layoutManager instanceof GridLayoutManager) {
mLayoutManagerType = layoutManagerType.GRID_LAYOUT;
} else if (layoutManager instanceof StaggeredGridLayoutManager) {
mLayoutManagerType = layoutManagerType.STAGGERED_GRID_LAYOUT;
} else {
throw new RuntimeException(Unsupported LayoutManager used. Valid ones are LinearLayoutManager, GridLayoutManager and StaggeredGridLayoutManager);
}
}
switch (mLayoutManagerType) {
case LINEAR_LAYOUT:
lastVisibleItemPosition = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();
break;
case GRID_LAYOUT:
lastVisibleItemPosition = ((GridLayoutManager) layoutManager).findLastVisibleItemPosition();
break;
case STAGGERED_GRID_LAYOUT:
StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
if (lastPositions == null) {
lastPositions = new int[staggeredGridLayoutManager.getSpanCount()];
}
staggeredGridLayoutManager.findLastVisibleItemPositions(lastPositions);
lastVisibleItemPosition = findMax(lastPositions);
break;
default:
break;
}
}
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
currentScrollState = newState;
RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
int visibleItemCount = layoutManager.getChildCount();
int totalItemCount = layoutManager.getItemCount();
if (visibleItemCount > 0 && currentScrollState == RecyclerView.SCROLL_STATE_IDLE
&& lastVisibleItemPosition >= totalItemCount - 1) {
if (!isLoadingMore()){
mIsLoadingMore =true;
onStart();
onLoadMore();
}
}
}
private int findMax(int[] lastPositions) {
int max = lastPositions[0];
for (int value : lastPositions) {
if (value > max) {
max = value;
}
}
return max;
}
具體邏輯見代碼，LinearLayoutManager 和 GridLayoutManager的處理邏輯類似，只不過StaggeredGridLayoutManager 的處理稍微復雜一點，因為布局是錯亂的，所以需要自己找到最底下的布局是哪一個，關鍵代碼就是這兩句
staggeredGridLayoutManager.findLastVisibleItemPositions(lastPositions);
lastVisibleItemPosition = findMax(lastPositions);
就這樣子，其實已經出現了上拉加載更多的功能了，這時候你使用一下這個滾動監聽，是完全沒有什麼問題的，只不過沒有顯示Footer布局而已。接下來我們最重要的事就是改造適配器。
extends RecyclerView.Adapter{ public interface Item { int TYPE_HEADER = 0; int TYPE_FOOTER = 1; /** * 返回item類型，其值不能為0或者1； * * @return */ int getType(); } } data-snippet-id=ext.01de7a81de0436de231e7ad760887dc6 data-snippet-saved=false data-csrftoken=nYu9aDrN-39XDjVOtmj-NZc7IqaJOGHYqM2M data-codota-status=done> public abstract class RecyclerViewAdapterextends RecyclerView.Adapter { public interface Item { int TYPE_HEADER = 0; int TYPE_FOOTER = 1; /** * 返回item類型，其值不能為0或者1； * * @return */ int getType(); } }
這是最基本的結構，內部定義了上面提到的Item接口，我們的Item實體類需要實現該接口，用於判斷Item的類型。
定義Getter和Setter方法
list = null;
protected int headerViewRes;
protected int footerViewRes;
protected boolean hasHeader = false;
protected boolean hasFooter = false;
public List getList() {
return list;
}
public void setList(List list) {
this.list = list;
}
public boolean isHeader(int position) {
return hasHeader() && position == 0;
}
public boolean isFooter(int position) {
if(hasHeader()){
return hasFooter() && position == list.size() + 1;
}else {
return hasFooter() && position == list.size();
}
}
public int getHeaderView() {
return headerViewRes;
}
public int getFooterView() {
return footerViewRes;
}
public void setHeaderView(int headerViewRes) {
if (headerViewRes != 0) {
if (!hasHeader()){
this.headerViewRes = headerViewRes;
this.hasHeader = true;
notifyItemInserted(0);
}else{
this.headerViewRes = headerViewRes;
notifyDataSetChanged();
}
} else {
if (hasHeader()){
this.hasHeader = false;
notifyItemRemoved(0);
}
}
}
public void setFooterView(int footerViewRes) {
if (footerViewRes != 0) {
if (!hasFooter()){
this.footerViewRes = footerViewRes;
this.hasFooter = true;
if (hasHeader()){
notifyItemInserted(list.size()+1);
}else{
notifyItemInserted(list.size());
}
}else{
this.footerViewRes = footerViewRes;
notifyDataSetChanged();
}
} else {
if(hasFooter()){
this.hasFooter = false;
if (hasHeader()){
notifyItemRemoved(list.size()+1);
}else{
notifyItemRemoved(list.size());
}
}
}
}
public boolean hasHeader() {
return hasHeader;
}
public boolean hasFooter() {
return hasFooter;
}
data-snippet-id=ext.72dd5fef3970bc085d96a545ec056844 data-snippet-saved=false data-csrftoken=G8UjOima-1-KCwXw_kyU44e5miZtTO5o-yE8 data-codota-status=done> protected List list = null;
protected int headerViewRes;
protected int footerViewRes;
protected boolean hasHeader = false;
protected boolean hasFooter = false;
public List getList() {
return list;
}
public void setList(List list) {
this.list = list;
}
public boolean isHeader(int position) {
return hasHeader() && position == 0;
}
public boolean isFooter(int position) {
if(hasHeader()){
return hasFooter() && position == list.size() + 1;
}else {
return hasFooter() && position == list.size();
}
}
public int getHeaderView() {
return headerViewRes;
}
public int getFooterView() {
return footerViewRes;
}
public void setHeaderView(int headerViewRes) {
if (headerViewRes != 0) {
if (!hasHeader()){
this.headerViewRes = headerViewRes;
this.hasHeader = true;
notifyItemInserted(0);
}else{
this.headerViewRes = headerViewRes;
notifyDataSetChanged();
}
} else {
if (hasHeader()){
this.hasHeader = false;
notifyItemRemoved(0);
}
}
}
public void setFooterView(int footerViewRes) {
if (footerViewRes != 0) {
if (!hasFooter()){
this.footerViewRes = footerViewRes;
this.hasFooter = true;
if (hasHeader()){
notifyItemInserted(list.size()+1);
}else{
notifyItemInserted(list.size());
}
}else{
this.footerViewRes = footerViewRes;
notifyDataSetChanged();
}
} else {
if(hasFooter()){
this.hasFooter = false;
if (hasHeader()){
notifyItemRemoved(list.size()+1);
}else{
notifyItemRemoved(list.size());
}
}
}
}
public boolean hasHeader() {
return hasHeader;
}
public boolean hasFooter() {
return hasFooter;
}
內部邏輯看上去一大堆，其實並不復雜，關鍵是需要判斷Header存不存在，Header存在與不存在的情況下Footer的位置是不同的，注意這一點，編寫對應的邏輯即可，當然你的邏輯可以與我不同。
接下來是構造函數，傳入我們的數據集，Header和Footer的布局資源
list) {
this.list = list;
}
public RecyclerViewAdapter(List list, int headerViewRes) {
this.list = list;
setHeaderView(headerViewRes);
}
public RecyclerViewAdapter(List list, int headerViewRes, int footerViewRes) {
this.list = list;
setHeaderView(headerViewRes);
setFooterView(footerViewRes);
} data-snippet-id=ext.6372b2bda1ab6b1e7140ac92cd96e966 data-snippet-saved=false data-csrftoken=k6EABupp-4lQ3IJEjk1h7etGMpwNpCMNrukE data-codota-status=done> public RecyclerViewAdapter(List list) {
this.list = list;
}
public RecyclerViewAdapter(List list, int headerViewRes) {
this.list = list;
setHeaderView(headerViewRes);
}
public RecyclerViewAdapter(List list, int headerViewRes, int footerViewRes) {
this.list = list;
setHeaderView(headerViewRes);
setFooterView(footerViewRes);
}
實現我們的Header布局和Footer布局的ViewHolder，其實就是定義兩個類
static class HeaderViewHolder extends RecyclerView.ViewHolder {
public HeaderViewHolder(View itemView) {
super(itemView);
}
}
static class FooterViewHolder extends RecyclerView.ViewHolder {
public FooterViewHolder(View itemView) {
super(itemView);
}
}
重寫getItemCount和getItemViewType方法
getItemCount中我們需要根據是否有Header和Footer來返回對應的Item數
@Override
public int getItemCount() {
int count = 0;
count += (hasHeader() ? 1 : 0);
count += (hasFooter() ? 1 : 0);
count += list.size();
return count;
}
getItemViewType就需要根據判斷位置判斷是否具有Header來判斷對應的Item的類型
@Override
public int getItemViewType(int position) {
int size = list.size();
if (hasHeader()) {
if (position == 0) {
return Item.TYPE_HEADER;
} else {
if (position == size + 1) {
return Item.TYPE_FOOTER;
} else {
return list.get(position - 1).getType();
}
}
} else {
if (position == size) {
return Item.TYPE_FOOTER;
} else {
return list.get(position).getType();
}
}
}
創建ViewHolder，根據類型的不同創建對應的ViewHolder，如果不是Header和Footer之外的類型，交由抽象方法onCreateHolder處理
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (hasHeader() && viewType == Item.TYPE_HEADER) {
View v = LayoutInflater.from(parent.getContext()).inflate(getHeaderView(), parent, false);
return new HeaderViewHolder(v);
} else if (hasFooter() && viewType == Item.TYPE_FOOTER) {
View v = LayoutInflater.from(parent.getContext()).inflate(getFooterView(), parent, false);
return new FooterViewHolder(v);
} else {
return onCreateHolder(parent, viewType);
}
}
public abstract RecyclerView.ViewHolder onCreateHolder(ViewGroup parent, int viewType);
綁定數據，同創建ViewHolder，根據位置的不同來獲得item的類型，如果是Header就回調抽象方法onBindHeaderView，如果是Footer就回調抽象方法onBindFooterView，否則就回調抽象方法onBindItemView，將對應的holder和實體類傳入。
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (getItemViewType(position) == Item.TYPE_HEADER) {
HeaderViewHolder headerHolder = (HeaderViewHolder) holder;
View headerView = headerHolder.itemView;
onBindHeaderView(headerView);
} else if (getItemViewType(position) == Item.TYPE_FOOTER) {
FooterViewHolder footerHolder = (FooterViewHolder) holder;
View footerView = footerHolder.itemView;
onBindFooterView(footerView);
} else {
T i = getItemByPosition(position);
onBindItemView(holder, i);
}
}
protected abstract void onBindHeaderView(View headerView);
protected abstract void onBindFooterView(View footerView);
protected abstract void onBindItemView(RecyclerView.ViewHolder holder, T item);
這樣子，已經能夠處理Header和Footer了，但是顯示位置還是不正確的，接下來我們需要對GridLayout和StaggeredGridLayout做特殊處理。
定義抽象類GridLayoutAdapter繼承RecyclerViewAdapter
extends RecyclerViewAdapter{ public GridLayoutAdapter(List list) { super(list); } public GridLayoutAdapter(List list, int headerViewRes) { super(list, headerViewRes); } public GridLayoutAdapter(List list, int headerViewRes, int footerViewRes) { super(list, headerViewRes, footerViewRes); } } data-snippet-id=ext.5cd27c2bff04b4da41feaaf441a38265 data-snippet-saved=false data-csrftoken=w9Cl4TWF-O0ViW_ZUngJb8YbZI0s7dPij290 data-codota-status=done> public abstract class GridLayoutAdapterextends RecyclerViewAdapter { public GridLayoutAdapter(List list) { super(list); } public GridLayoutAdapter(List list, int headerViewRes) { super(list, headerViewRes); } public GridLayoutAdapter(List list, int headerViewRes, int footerViewRes) { super(list, headerViewRes, footerViewRes); } }
定義一個內部類GridSpanSizeLookup 繼承GridLayoutManager.SpanSizeLookup，調用父類isHeader和isFooter方法判斷是否是頭或者尾，如果是則返回gridManager.getSpanCount();即一個item占據一行的span數，否則就返回1
class GridSpanSizeLookup extends GridLayoutManager.SpanSizeLookup {
@Override
public int getSpanSize(int position) {
if (isHeader(position) || isFooter(position)) {
return gridManager.getSpanCount();
}
return 1;
}
}
最重要的一步就是重寫onAttachedToRecyclerView，判斷是否是GridLayout布局，然後通過setSpanSizeLookup設置為我們的內部類
private GridSpanSizeLookup mGridSpanSizeLookup;
private GridLayoutManager gridManager;
@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();
if (manager instanceof GridLayoutManager) {
gridManager = ((GridLayoutManager) manager);
if (mGridSpanSizeLookup == null) {
mGridSpanSizeLookup = new GridSpanSizeLookup();
}
gridManager.setSpanSizeLookup(mGridSpanSizeLookup);
}
}
同理，瀑布流布局也需要進行同樣的操作。
extends RecyclerViewAdapter{ public StaggeredGridLayoutAdapter(List list) { super(list); } public StaggeredGridLayoutAdapter(List list, int headerViewRes) { super(list, headerViewRes); } public StaggeredGridLayoutAdapter(List list, int headerViewRes, int footerViewRes) { super(list, headerViewRes, footerViewRes); } } data-snippet-id=ext.e812372627c676958c74437dfafa2b7e data-snippet-saved=false data-csrftoken=rwV4GwoP-01GxkZUjrV3hy5T16J6sdHVtNfw data-codota-status=done> public abstract class StaggeredGridLayoutAdapterextends RecyclerViewAdapter { public StaggeredGridLayoutAdapter(List list) { super(list); } public StaggeredGridLayoutAdapter(List list, int headerViewRes) { super(list, headerViewRes); } public StaggeredGridLayoutAdapter(List list, int headerViewRes, int footerViewRes) { super(list, headerViewRes, footerViewRes); } }
但是 StaggeredGridLayoutManager中沒有setSpanSizeLookup方法，慶幸的是StaggeredGridLayoutManager.LayoutParams中有setFullSpan方法可以達到同樣的效果。
這時候重寫的不再是onAttachedToRecyclerView方法而是onViewAttachedToWindow方法
@Override
public void onViewAttachedToWindow(RecyclerView.ViewHolder holder) {
super.onViewAttachedToWindow(holder);
if (isStaggeredGridLayout(holder)) {
handleLayoutIfStaggeredGridLayout(holder, holder.getLayoutPosition());
}
}
private boolean isStaggeredGridLayout(RecyclerView.ViewHolder holder) {
ViewGroup.LayoutParams layoutParams = holder.itemView.getLayoutParams();
if (layoutParams != null && layoutParams instanceof StaggeredGridLayoutManager.LayoutParams) {
return true;
}
return false;
}
protected void handleLayoutIfStaggeredGridLayout(RecyclerView.ViewHolder holder, int position) {
if (isHeader(position) || isFooter(position)) {
StaggeredGridLayoutManager.LayoutParams p = (StaggeredGridLayoutManager.LayoutParams) holder.itemView.getLayoutParams();
p.setFullSpan(true);
}
}
基本上，到這裡為止，就完成了所有的工作，在使用的時候要實現上拉加載顯示Footer，如果是瀑布流布局，就需要繼承StaggeredGridLayoutAdapter，如果是網格布局，就需要繼承GridLayoutAdapter，其他情況下，繼承RecyclerViewAdapter即可。
為了演示，這裡簡單進行使用，首先定義一個Item的實現類
public class Content implements RecyclerViewAdapter.Item {
private int TYPE = 2;
private String title;
private String desc;
private String url;
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
public String getIconUrl() {
return url;
}
public void setIconUrl(String iconUrl) {
this.url = iconUrl;
}
@Override
public String toString() {
return Content{ +
title=' + title + ''' +
, desc=' + desc + ''' +
, icon= + url +
'}';
}
@Override
public int getType() {
return TYPE;
}
}
我們這裡以瀑布流布局為例，因此繼承StaggeredGridLayoutAdapter實現我們的適配器。
{
public MyAdapter(List list, int headerViewRes) {
super(list, headerViewRes);
}
public MyAdapter(List list) {
super(list);
}
public MyAdapter(List list, int headerViewRes, int footerViewRes) {
super(list, headerViewRes, footerViewRes);
}
@Override
public RecyclerView.ViewHolder onCreateHolder(ViewGroup parent, int viewType) {
View view=LayoutInflater.from(parent.getContext()).inflate(R.layout.item_content,parent,false);
return new ItemViewHolder(view);
}
@Override
protected void onBindHeaderView(View headerView) {
Log.e(TAG,這是HeadView數據綁定的過程);
ImageView imageView= (ImageView) headerView.findViewById(R.id.icon);
Picasso.with(headerView.getContext()).load(http://img.my.csdn.net/uploads/201508/05/1438760758_3497.jpg).into(imageView);
}
@Override
protected void onBindFooterView(View footerView) {
Log.e(TAG,這是FootView數據綁定的過程);
}
@Override
protected void onBindItemView(RecyclerView.ViewHolder holder, Content item) {
ItemViewHolder itemViewHolder = (ItemViewHolder) holder;
Picasso.with(holder.itemView.getContext()).load(item.getIconUrl()).into( itemViewHolder.icon);
itemViewHolder.title.setText(item.getTitle());
itemViewHolder.desc.setText(item.getDesc());
}
static class ItemViewHolder extends RecyclerView.ViewHolder {
ImageView icon;
TextView title;
TextView desc;
public ItemViewHolder(View itemView) {
super(itemView);
icon = (ImageView) itemView.findViewById(R.id.icon);
title = (TextView) itemView.findViewById(R.id.title);
desc = (TextView) itemView.findViewById(R.id.desc);
}
}
}
data-snippet-id=ext.4d4a7785a31c04496906dd3c9d1b521f data-snippet-saved=false data-csrftoken=o878nlHA-zddyMlPClI7Ynxp04ZUqleF9Ko8 data-codota-status=done>public class MyAdapter extends StaggeredGridLayoutAdapter {
public MyAdapter(List list, int headerViewRes) {
super(list, headerViewRes);
}
public MyAdapter(List list) {
super(list);
}
public MyAdapter(List list, int headerViewRes, int footerViewRes) {
super(list, headerViewRes, footerViewRes);
}
@Override
public RecyclerView.ViewHolder onCreateHolder(ViewGroup parent, int viewType) {
View view=LayoutInflater.from(parent.getContext()).inflate(R.layout.item_content,parent,false);
return new ItemViewHolder(view);
}
@Override
protected void onBindHeaderView(View headerView) {
Log.e(TAG,這是HeadView數據綁定的過程);
ImageView imageView= (ImageView) headerView.findViewById(R.id.icon);
Picasso.with(headerView.getContext()).load(http://img.my.csdn.net/uploads/201508/05/1438760758_3497.jpg).into(imageView);
}
@Override
protected void onBindFooterView(View footerView) {
Log.e(TAG,這是FootView數據綁定的過程);
}
@Override
protected void onBindItemView(RecyclerView.ViewHolder holder, Content item) {
ItemViewHolder itemViewHolder = (ItemViewHolder) holder;
Picasso.with(holder.itemView.getContext()).load(item.getIconUrl()).into( itemViewHolder.icon);
itemViewHolder.title.setText(item.getTitle());
itemViewHolder.desc.setText(item.getDesc());
}
static class ItemViewHolder extends RecyclerView.ViewHolder {
ImageView icon;
TextView title;
TextView desc;
public ItemViewHolder(View itemView) {
super(itemView);
icon = (ImageView) itemView.findViewById(R.id.icon);
title = (TextView) itemView.findViewById(R.id.title);
desc = (TextView) itemView.findViewById(R.id.desc);
}
}
}
使用也很簡單，在onStart中顯示footer，在onLoadMore中加載數據，這裡是模擬操作，異步返回數據後將數據傳入onFinish進行回調，回調完成後記得調用 setLoadingMore(false);來通知當前處於沒在加載的狀態，通過Handler發送數據到主線程進行UI更新，並因此Footer
public class MainActivity extends AppCompatActivity {
private RecyclerView mRecyclerView;
private List list = new ArrayList();
private RecyclerViewAdapter myAdapter;
private ArrayList arrayList;
Handler mHandler=new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
List list= (List) msg.obj;
myAdapter.getList().addAll(list);
myAdapter.notifyDataSetChanged();
myAdapter.setFooterView(0);
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRecyclerView = (RecyclerView) findViewById(R.id.recyclerview);
initData();
//mRecyclerView.setLayoutManager(new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false));
mRecyclerView.setLayoutManager(new GridLayoutManager(this,2));
// mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL));
myAdapter = new MyAdapter(list);
//myAdapter.setHeaderView(R.layout.item_header);
//myAdapter.setFooterView(R.layout.item_footer);
mRecyclerView.setAdapter(myAdapter);
arrayList=new ArrayList(myAdapter.getList());
mRecyclerView.addOnScrollListener(new OnRecyclerViewScrollListener(){
@Override
public void onStart() {
myAdapter.setFooterView(R.layout.item_footer);
if (myAdapter.hasHeader()){
mRecyclerView.smoothScrollToPosition(myAdapter.getItemCount()+1);
}else{
mRecyclerView.smoothScrollToPosition(myAdapter.getItemCount());
}
}
@Override
public void onLoadMore() {
new Thread(new Runnable() {
@Override
public void run() {
try {
Log.e(TAG,模擬網絡請求數據);
Thread.sleep(5000);
//手動調用onFinish()
onFinish(arrayList);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}).start();
}
@Override
public void onFinish(List contents) {
Message message=Message.obtain();
message.obj=contents;
mHandler.sendMessage(message);
setLoadingMore(false);
}
});
}
private void initData() {
Content c = new Content();
c.setIconUrl(http://p1.meituan.net/63.90/movie/7a29814fe6549b929df6e0ef9575ce699434172.jpg);
c.setTitle(搖滾水果);
c.setDesc(比基尼女郎，掀搖滾熱浪。濱江區濱文路577號華潤超市4樓。);
list.add(c);
//類似這樣的添加數據的過程，還有很多數據。。這裡不貼出來了
}
}
最終的效果看動圖，如下
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