5.0之后 推出的RecycleView来代替ListView，可以说RecycleView和ListView比起有过之而无不及，下面这篇博客主要来实现RecyclerView的上拉加载更多功能。

基本思路是让RecyclerView的Adapter加载两种布局，第一个布局来显示主界面，第二个布局来显示上拉加载时的提示信息，让RecyclerView监听是否滑动到最后一个item，如果是，则调用上拉刷新的逻辑，拉取远程数据，并显示第二个布局。等加载完毕时，刷新Adapter，并隐藏第二个布局.

下面主要是针对 对RecyclerAdapter的修饰封装，一般我们在使用RecycleView的时候会将RecycleAdapter和RecycleHolder分开进行封装，在使用的时候，就会很方便(这两个类就不贴了，各自有各自的实现)。

先贴两个博客地址翔哥和傻子斌的添加haedView和footVIew的具体操作，因为下拉刷新和上拉加载就是基于添加这个来实现。

1.核心实现

@Override

public int getItemViewType(int position) {

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

return TYPE_FOOTER;

} else {

return TYPE_ITEM;

}

}

@Override

public int getItemCount() {

return super.getItemCount() + 1;

}

用过listView的人都知道这两个方法，可以说很大程度上和listView一样，不过ListView有自带的addHead 和 addFoot的方法，RecycleView则没有，所以就需要我们在Adapter中对其进行实现。

2.实现上拉加载更多

public abstract class BasePullUpRecyclerAdapter extends BaseRecyclerAdapter {

public static final int TYPE_FOOTER = 0;//两种状态 footview显示的时候和不显示的一般item

public static final int TYPE_ITEM = 1;

public static final int STATE_INVISIBLE = 0;//footView的四种状态 不可见 加载中 没有更多 没有数据

public static final int STATE_LOADING = 1;

public static final int STATE_NO_MORE = 2;

public static final int STATE_NO_DATA = 3;

protected int state = STATE_LOADING;//默认为加载中

protected FooterView footerView;//footView

private OnPullUpListener pullUpListener;//上拉监听

public BasePullUpRecyclerAdapter(RecyclerView v, Collection datas, int itemLayoutId) {

super(v, datas, itemLayoutId);

v.addOnScrollListener(new BasePullUpScrollListener());//将自定义的监听添加进Adapter

footerView = new FooterView(cxt);//初始化自定义的FootView

}

@Override

public int getItemViewType(int position) {//根据不同的位置设置不同的类型状态

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

return TYPE_FOOTER;

} else {

return TYPE_ITEM;

}

}

@Override

public int getItemCount() {//

return super.getItemCount() + 1;

}

@Override

public RecyclerHolder onCreateViewHolder(ViewGroup parent, int viewType) {

if (viewType == TYPE_ITEM) {

return super.onCreateViewHolder(parent, viewType);

} else if (viewType == TYPE_FOOTER) {

refreshFooterView();

return new RecyclerHolder(footerView);

}

return null;

}

@Override

public void onBindViewHolder(RecyclerHolder holder, int position) {

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

//因为已经在footerview写死了，所以这里就不用再去设置

//没有数据的时候也不显示footer

if (position == 0) {

getFooterView().setVisibility(View.GONE);

}

} else {

super.onBindViewHolder(holder, position);

}

}

public int getState() {//返回状态

return this.state;

}

public void setState(int state) {//设置不同的状态然后更新footView

this.state = state;

refreshFooterView();

}

/**

* 获取底部的FooterView

*

* @return

*/

public FooterView getFooterView() {

return this.footerView;

}

/**

* 滚动到底部时的监听器

*

* @param l

*/

public void setPullUpListener(OnPullUpListener l) {

this.pullUpListener = l;

}

private void refreshFooterView() {

switch (state) {

case STATE_INVISIBLE:

footerView.setInVisibleState();

break;

case STATE_LOADING:

footerView.setLoadingState();

break;

case STATE_NO_MORE:

footerView.setNoMoreState();

break;

case STATE_NO_DATA:

footerView.setNoDataState();

break;

}

} ········

3.实现对不同的Layout进行适配

/**

* 监听，判断RecyclerView滚动到底部时，加载onBottom方法

*/

public class BasePullUpScrollListener extends RecyclerView.OnScrollListener {

public static final int LINEAR = 0;

public static final int GRID = 1;

public static final int STAGGERED_GRID = 2;

//标识RecyclerView的LayoutManager是哪种

protected int layoutManagerType;

// 瀑布流的最后一个的位置

protected int[] lastPositions;

// 最后一个的位置

protected int lastVisibleItem;

@Override

public void onScrollStateChanged(RecyclerView recyclerView, int newState) {

super.onScrollStateChanged(recyclerView, newState);

if (newState == RecyclerView.SCROLL_STATE_IDLE && lastVisibleItem + 1 >=

getItemCount() && pullUpListener != null) {

pullUpListener.onBottom(state);//回调加载更多监听

}

}

//根据不同的Layout类型处理FootView

@Override

public void onScrolled(RecyclerView recyclerView, int dx, int dy) {

super.onScrolled(recyclerView, dx, dy);

RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();

if (layoutManager instanceof LinearLayoutManager) {

layoutManagerType = LINEAR;

} else if (layoutManager instanceof GridLayoutManager) {

layoutManagerType = GRID;

} else if (layoutManager instanceof StaggeredGridLayoutManager) {

layoutManagerType = STAGGERED_GRID;

} else {

throw new RuntimeException(

"Unsupported LayoutManager used. Valid ones are " +

"LinearLayoutManager, GridLayoutManager and " +

"StaggeredGridLayoutManager");

}

switch (layoutManagerType) {

case LINEAR:

lastVisibleItem = ((LinearLayoutManager) layoutManager)

.findLastVisibleItemPosition();

break;

case GRID:

lastVisibleItem = ((GridLayoutManager) layoutManager)

.findLastVisibleItemPosition();

break;

case STAGGERED_GRID:

StaggeredGridLayoutManager staggeredGridLayoutManager

= (StaggeredGridLayoutManager) layoutManager;

lastPositions = new int[staggeredGridLayoutManager.getSpanCount()];

staggeredGridLayoutManager.findLastVisibleItemPositions(lastPositions);

lastVisibleItem = findMax(lastPositions);

break;

}

}

private int findMax(int[] lastPositions) {

int max = lastPositions[0];

for (int value : lastPositions) {

if (value > max) {

max = value;

}

}

return max;

}

}

4.自定义的footView(可根据自己需求自定义)

public class FooterView extends LinearLayout {

protected String loadingText = "加载中…";

protected String noMoreText = "已加载全部";

protected String noDataText = "暂无内容";

private final TextView textView;

private final ProgressBar progressBar;

public FooterView(Context context) {

super(context);

textView = new TextView(context);

progressBar = new ProgressBar(context);

init(context);

}

public void init(Context context) {

this.setOrientation(HORIZONTAL);

this.setGravity(Gravity.CENTER);

LayoutParams params = new LayoutParams(LayoutParams.MATCH_PARENT,

LayoutParams.WRAP_CONTENT);

params.gravity = Gravity.CENTER;

params.height = dip2px(23);

this.setLayoutParams(params);

progressBar.setIndeterminate(true);

LayoutParams progressBarparams = new LayoutParams(LayoutParams.WRAP_CONTENT,

LayoutParams.WRAP_CONTENT);

progressBarparams.width = progressBarparams.height = dip2px(22);

progressBar.setLayoutParams(progressBarparams);

LayoutParams textViewparams = new LayoutParams(LayoutParams.WRAP_CONTENT, dip2px(20));

textView.setTextColor(0xff666666);

textView.setTextSize(16);

textView.setLayoutParams(textViewparams);

this.addView(progressBar);

this.addView(textView);

}

public void setText(CharSequence s) {

textView.setText(s);

}

public void setTextColor(int color) {

textView.setTextColor(color);

}

public void setTextSize(float size) {

textView.setTextSize(size);

}

public void setNoDataState() {

this.setVisibility(View.VISIBLE);

progressBar.setVisibility(View.GONE);

textView.setVisibility(View.VISIBLE);

textView.setText(noDataText);

}

public void setNoMoreState() {

this.setVisibility(View.VISIBLE);

progressBar.setVisibility(View.GONE);

textView.setVisibility(View.VISIBLE);

textView.setText(noMoreText);

}

public void setLoadingState() {

this.setVisibility(View.VISIBLE);

progressBar.setVisibility(View.VISIBLE);

textView.setVisibility(View.VISIBLE);

textView.setText(loadingText);

}

public ProgressBar getProgressBar() {

return progressBar;

}

public void setInVisibleState() {

this.setVisibility(View.GONE);

}

public void setLoadingText(String loadingText) {

this.loadingText = loadingText;

}

public void setNoMoreText(String noMoreText) {

this.noMoreText = noMoreText;

}

public void setNoDataText(String noDataText) {

this.noDataText = noDataText;

}

public int dip2px(float dpValue) {

Resources r = getResources();

float px = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,

dpValue, r.getDisplayMetrics());

return (int) px;

}

}

之所以都用代码来写，不用xml布局，为了减少一个xml布局，实际这个View的布局也不复杂，一个RelativeLayout就可以搞定了。就不具体注释来说明了，都看得懂

5.具体使用

1.对适配器进行监听，设置加载中 和 加载数据

mAdapter.setPullUpListener(new BasePullUpRecyclerAdapter.OnPullUpListener() {

@Override

public void onBottom(int state) {

mAdapter.setState(BasePullUpRecyclerAdapter.STATE_LOADING);

mPresenter.load();

}

});

2.在数据返回的时候对其进行处理

public void onEvent(MessageEventNew event) {

setLoadingIndicator(false);

if (event.code == ModelEvent.SUCCESS) {

if (event.list == null || event.list.size() == 0) {//如果没有数据，就设置为STATE_NO_MORE

onContentEmpty();

mAdapter.setState(BasePullUpRecyclerAdapter.STATE_NO_MORE);

} else {

lastMessageId = event.list.get(event.list.size() - 1).id;

if(lastMessageId==newLastId){//否则加载的数据和上一次加载的数据是否相同来判断是NOMORE还是有数据然后隐藏

mAdapter.setState(BasePullUpRecyclerAdapter.STATE_NO_MORE);

}else {

mAdapter.setState(BasePullUpRecyclerAdapter.STATE_INVISIBLE);

}

showContent(event.list);

newLastId = lastMessageId;

}

} else {

ViewKit.shortToast(event.message);

onNetwork();

}

}