封装Recycleview.Adapter使Recycleview具有加载更多，item点击事件等功能

Recycleview简介：

类似Recycleview使用的文章很多，这里简单介绍一下：RecyclerView是support-v7包中的新组件，自带布局复用与ViewHolder，Recycleview不关心UI的显示方式，由LayoutManager实现类控制显示方式。如果你还没使用过Recycleview，建议先写一个ListView样式的Recycleview
demo.

需要解决的问题：

1.下拉刷新，上拉加载是ListView中最常用的功能。下拉刷新可以使用V7包中SwipeRefreshLayout等实现，加载更多如何实现呢？
2.列表显示中多种布局也是常见的功能，Recycleview如何实现呢。
3.使用时会不会很失望，怎么没有item点击事件呢？

一个个来解决：

[b]废话少说，放码过来：
[/b]

public abstract  class MCyclerAdapter<T>extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
protected List<T> list;
protected Context context;
protected LayoutInflater inflater;
private final static int FOOT_TYPE = 99;

/**
* 设置自己的底部加载更多的布局
* @param customFootView
*/
public void setCustomFootView(View customFootView) {
isLoadMore = true;
this.customFootView = customFootView;
}

private View customFootView;
public boolean isMultiType() {
return isMultiType;
}

public boolean isLoadMore() {
return isLoadMore;
}

/**
* 设置是否底部显示加载更多，默认不显示
* @param isLoadMore
*/
public void setIsLoadMore(boolean isLoadMore) {
this.isLoadMore = isLoadMore;
}

private boolean isLoadMore = false;

/**
* 设置是否是多种布局，默认单一布局
* @param isMultiType
*/
public void setIsMultiType(boolean isMultiType) {
this.isMultiType = isMultiType;
}

private boolean isMultiType = false;
public MCyclerAdapter(List<T> list,Context context){
this.list = list;
this.context = context;
inflater = LayoutInflater.from(context);
}

/**
* 如果你的item布局是多种，需要复写这个方法
* @param postion
* @return
*/
public abstract int getDisplayType(int postion);
@Override
public int getItemViewType(int position) {
if (isLoadMore&&position==getItemCount()-1){
return  FOOT_TYPE;
}
if (isMultiType){
return  getDisplayType(position);
}
return super.getItemViewType(position);
}

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (isLoadMore&&viewType==FOOT_TYPE){
View view = null;
if (customFootView!=null){
view = customFootView;
}else {
view = inflater.inflate(R.layout.bottom_progressbar,parent,false);
}
return  new FootHolder(view);
}

return onCreateDisplayHolder(parent, viewType);
}

public abstract RecyclerView.ViewHolder onCreateDisplayHolder(ViewGroup parent,int viewType);

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {

if (isLoadMore&&position==getItemCount()-1){

if (moreListerner!=null){
handler.sendEmptyMessageDelayed(11,300);
}
retu
4000
rn;
}
onBindData(holder,position);
}

public abstract void onBindData(RecyclerView.ViewHolder holder, int position);

/**
* 返回列表长度
* @return
*/
@Override
public int getItemCount() {

if (isLoadMore)
return  list==null||list.size()==0?0:list.size()+1;
return list==null||list.size()==0?0:list.size();
}

class FootHolder extends RecyclerView.ViewHolder{
public FootHolder(View itemView) {
super(itemView);
}
}

public OnLoadMoreListerner getMoreListerner() {
return moreListerner;
}

public void setMoreListerner(OnLoadMoreListerner moreListerner) {
this.moreListerner = moreListerner;
}

private OnLoadMoreListerner moreListerner;

public interface OnLoadMoreListerner{
public void loadMore();

}

Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);

moreListerner.loadMore();

}
};

/**
* 如果你需要有item的点击事件，你自己的ViewHolder extends BaseHolder
*/
class BaseHolder extends RecyclerView.ViewHolder{

public CycleItemClilkListener getCycleItemClilkListener() {
return cycleItemClilkListener;
}

public void setCycleItemClilkListener(CycleItemClilkListener cycleItemClilkListener) {
this.cycleItemClilkListener = cycleItemClilkListener;
}

private CycleItemClilkListener cycleItemClilkListener;
public BaseHolder(View itemView,CycleItemClilkListener listener) {
super(itemView);
cycleItemClilkListener = listener;
itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {

if (cycleItemClilkListener!=null){
cycleItemClilkListener.onCycleItemClick(v,getPosition());
}
}
});
}
}

public interface CycleItemClilkListener{
void onCycleItemClick(View view,int position);
}
}

1.思路是滚动到末尾位置时加载一个Foot布局，isLoadMore用于标记是否需要加载更多默认不需要，
getItemCount返回长度，注意需要加载更多时长度是数据长度+1

public int getItemViewType(int position) {
if (isLoadMore&&position==getItemCount()-1){
return  FOOT_TYPE;
}
if (isMultiType){
return  getDisplayType(position);
}
return super.getItemViewType(position);
}

@Override
public int getItemCount() {

if (isLoadMore)
return  list==null||list.size()==0?0:list.size()+1;
return list==null||list.size()==0?0:list.size();
}

然后就要写FootHolder

public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {

if (isLoadMore&&position==getItemCount()-1){

if (moreListerner!=null){
handler.sendEmptyMessageDelayed(11,300);
}
return;
}
onBindData(holder,position);
}

2.多种布局与加载更多一个思路，这里我定义了一个抽象方法getDisplayType方便子类去实现

if (isMultiType){
return  getDisplayType(position);
}

3.因为在构造ViewHolder时，rootView将作为一个必传参数传递进来，所以我们只需要拿到rootView并给其绑定点击监听事件即可。这里我定义了一个带有点击事件的ViewHolder，需要时直接继承BaseViewHolder

class BaseHolder extends RecyclerView.ViewHolder{

public CycleItemClilkListener getCycleItemClilkListener() {
return cycleItemClilkListener;
}

public void setCycleItemClilkListener(CycleItemClilkListener cycleItemClilkListener) {
this.cycleItemClilkListener = cycleItemClilkListener;
}

private CycleItemClilkListener cycleItemClilkListener;
public BaseHolder(View itemView,CycleItemClilkListener listener) {
super(itemView);
cycleItemClilkListener = listener;
itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {

if (cycleItemClilkListener!=null){
cycleItemClilkListener.onCycleItemClick(v,getPosition());
}
}
});
}
}

public interface CycleItemClilkListener{
void onCycleItemClick(View view,int position);
}

一切就绪可以试一试效果了，定义一个adapter 继承MCyclerAdapter

public class Madapter extends MCyclerAdapter<DisplayData> {
@Override
public int getDisplayType(int postion) {
return list.get(postion).getType();
}

public Madapter(List<DisplayData> list, Context context) {
super(list, context);
}

@Override
public RecyclerView.ViewHolder onCreateDisplayHolder(ViewGroup parent, int viewType) {

View view = null;
RecyclerView.ViewHolder holder = null;
switch (viewType){
case DisplayData.TYPE_TXT:
view = inflater.inflate(R.layout.item_txt,parent,false);
holder = new TextHolder(view);
break;
case DisplayData.TYPE_IMG:
view = inflater.inflate(R.layout.item_img,parent,false);
holder = new ImageHolder(view);
break;
case DisplayData.TYPE_MULTI:
break;
}
return holder;
}

@Override
public void onBindData(RecyclerView.ViewHolder holder, int position) {

DisplayData data = list.get(position);
switch (getDisplayType(position)){
case DisplayData.TYPE_TXT:
TextHolder textHolder = (TextHolder)holder;
textHolder.mTxt.setText(data.getContent());
break;
case DisplayData.TYPE_IMG:
ImageHolder imageHolder = (ImageHolder)holder;
if (data.getContent().equals("1")){
imageHolder.mImg.setImageResource(R.drawable.img001);
}else{
imageHolder.mImg.setImageResource(R.drawable.img002);
}
break;
case DisplayData.TYPE_MULTI:
break;
}
}

class TextHolder extends BaseHolder{

TextView mTxt;
public TextHolder(View itemView) {
super(itemView, new CycleItemClilkListener() {
@Override
public void onCycleItemClick(View view, int position) {
Toast.makeText(context,position+"",Toast.LENGTH_SHORT).show();
}
});
mTxt = (TextView)itemView.findViewById(R.id.mText);
}
}

class ImageHolder extends  RecyclerView.ViewHolder{

ImageView mImg;
public ImageHolder(View itemView) {
super(itemView);
mImg = (ImageView)itemView.findViewById(R.id.mImg);
}
}

}

剩下的就是 new Adapter，setAdapter与listview无异
来看看效果~