封装三、 上滑刷新
思路是找到RecycleView滚动到底的消息，然后给它加上一个footer，依据数据加载的状态来显示不同的footer
核心类说明
- EndlessFooterUtils: 依据数据加载的状态改变底层footer的UI显示
- HugeRecyclerOnScrollListener: 滚动监听，可以在这里处理滚动结束，加载数据的动作
- EndlessFooterView：底层footer view，里面有不同状态对应的UI布局
1）先定义个footer view
依据loading, end(no more data), error显示不同的layout
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/loading_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:orientation="vertical">
<ViewStub
android:id="@+id/loading_viewstub"
android:layout_width="match_parent"
android:layout_height="@dimen/endless_footer_h"
android:layout="@layout/endless_footer_loading" />
<ViewStub
android:id="@+id/end_viewstub"
android:layout_width="match_parent"
android:layout_height="@dimen/endless_footer_h"
android:layout="@layout/endless_footer_end" />
<ViewStub
android:id="@+id/error_viewstub"
android:layout_width="match_parent"
android:layout_height="@dimen/endless_footer_h"
android:layout="@layout/endless_footer_error" />
</LinearLayout>
public class EndlessFooterView extends BaseEndlessFooterView {
public EndlessFooterView(Context context) {
this(context, null, 0);
}
public EndlessFooterView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public EndlessFooterView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
@Override
protected void setContentView(Context context) {
inflate(context, R.layout.endless_footer, this);
}
@Override
protected void setLoadingView() {
if (mLoadingView == null) {
ViewStub viewStub = (ViewStub) findViewById(R.id.loading_viewstub);
mLoadingView = viewStub.inflate();
}
}
@Override
protected void setErrorView() {
if (mErrorView == null) {
ViewStub viewStub = (ViewStub) findViewById(R.id.error_viewstub);
mErrorView = viewStub.inflate();
}
}
@Override
protected void setEndView() {
if (mTheEndView == null) {
ViewStub viewStub = (ViewStub) findViewById(R.id.end_viewstub);
mTheEndView = viewStub.inflate();
}
}
}
BaseEndlessFooterView主要处理一些view的显示逻辑
public abstract class BaseEndlessFooterView extends RelativeLayout {
private final static String TAG = "BaseEndlessFooterView";
// failed view
protected View mErrorView;
// end, no more data view
protected View mTheEndView;
// loading views
protected View mLoadingView;
// view state
protected State mState = State.Normal;
public enum State {
Normal, // normal status, not loading, normal show list
End, // no more data
Loading, // data loading
Error // load fail
}
// set view layout
protected abstract void setContentView(Context context);
// set loading view
protected abstract void setLoadingView();
// set error view
protected abstract void setErrorView();
// set end/no more data view
protected abstract void setEndView();
public BaseEndlessFooterView(Context context) {
this(context,null,0);
}
public BaseEndlessFooterView(Context context, AttributeSet attrs) {
this(context, attrs,0);
}
public BaseEndlessFooterView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initView(context);
}
private void initView(Context context) {
setContentView(context);
setOnClickListener(null);
setState(State.Normal);
// inflate views
setLoadingView();
setEndView();
setErrorView();
}
public State getState() {
return mState;
}
/**
* set endless footer status
*
* @param state status of endless footer view
*/
public void setState(State state) {
// check status
if (mState == state) {
Log.d(TAG, "setState, state not change, return");
return;
}
mState = state;
// hide all first
hideAllView();
// deal with different state
switch (state) {
case Normal:
setOnClickListener(null);
break;
case Loading:
dealLoading();
break;
case End:
dealEnd();
break;
case Error:
dealError();
break;
default:
break;
}
}
private void dealLoading() {
setOnClickListener(null);
if (mLoadingView != null) {
mLoadingView.setVisibility(VISIBLE);
}
}
private void dealEnd() {
setOnClickListener(null);
if (mTheEndView != null) {
mTheEndView.setVisibility(VISIBLE);
}
}
private void dealError() {
if (mErrorView != null) {
mErrorView.setVisibility(VISIBLE);
}
}
private void hideAllView() {
if (mLoadingView != null) {
mLoadingView.setVisibility(GONE);
}
if (mTheEndView != null) {
mTheEndView.setVisibility(GONE);
}
if (mErrorView != null) {
mErrorView.setVisibility(GONE);
}
}
}
2）封装了一个util来控制footer view的status
public class EndlessFooterUtils {
private static final String TAG = "EndlessFooterUtils";
private BaseEndlessFooterView mView;
public EndlessFooterUtils(BaseEndlessFooterView view) {
mView = view;
}
/**
* Sets end.you must set footer view before you use
*
* @param recyclerView the recycler view
* @param pageSize the page size
*/
public void setEnd(RecyclerView recyclerView, int pageSize) {
setFooterViewState(recyclerView, pageSize, BaseEndlessFooterView.State.End, null);
}
/**
* Sets normal.you must set footer view before you use
*
* @param recyclerView the recycler view
* @param pageSize the page size
*/
public void setNormal(RecyclerView recyclerView, int pageSize) {
setFooterViewState(recyclerView, pageSize, BaseEndlessFooterView.State.Normal, null);
}
/**
* Sets loading.you must set footer view before you use
*
* @param recyclerView the recycler view
* @param pageSize the page size
*/
public void setLoading(RecyclerView recyclerView, int pageSize) {
setFooterViewState(recyclerView, pageSize, BaseEndlessFooterView.State.Loading, null);
}
/**
* Sets error.you must set footer view before you use
*
* @param recyclerView the recycler view
* @param pageSize the page size
* @param errorListener error status listener
*/
public void setError(RecyclerView recyclerView, int pageSize,
View.OnClickListener errorListener) {
setFooterViewState(recyclerView, pageSize, BaseEndlessFooterView.State.Error, errorListener);
}
/**
* Sets footer view state.
*
* @param recyclerView the recycler view
* @param pageSize the page size
* @param state the state
* @param errorListener the error listener
*/
private void setFooterViewState(RecyclerView recyclerView, int pageSize,
BaseEndlessFooterView.State state, View.OnClickListener errorListener) {
if (mView == null) {
Log.e(TAG, "you must set footer view before you use");
throw new InvalidParameterException("you must call setFooterView to set footer view before you use");
}
// get adapter of recycler view
RecyclerView.Adapter adapter = recyclerView.getAdapter();
if (adapter == null) {
Log.w(TAG, "setFooterViewState adapter invalidate");
return;
}
BaseRecyclerAdapter eadapter = (BaseRecyclerAdapter) adapter;
// if less than one page, not need to add EndlessFooter
if (eadapter.getBasicItemCount() < pageSize) {
return;
}
// create or get endless footer
if (eadapter.getFooterView().size() <= 0) { // create a new endless footer view
eadapter.addFooterView(mView);
}
// set state
mView.setState(state);
// set error listener, if necessary
if (state == BaseEndlessFooterView.State.Error && errorListener != null) {
mView.setOnClickListener(errorListener);
}
}
/**
* get endless footer view status
*
* @param recyclerView recycler view
* @return the footer view state
*/
public BaseEndlessFooterView.State getFooterViewState(RecyclerView recyclerView) {
// get adapter of recycler view
RecyclerView.Adapter adapter = recyclerView.getAdapter();
if (adapter == null) {
Log.w(TAG, "getFooterViewState adapter invalidate");
return BaseEndlessFooterView.State.Normal;
}
// get endless footer view
BaseRecyclerAdapter eadapter = (BaseRecyclerAdapter) adapter;
if (eadapter.getFooterView().size() > 0) {
BaseEndlessFooterView endlessFooterView = (BaseEndlessFooterView) eadapter.getFooterView().get(0);
return endlessFooterView.getState();
}
return BaseEndlessFooterView.State.Normal;
}
}
3）现在来看看滚动事件
核心的思路是在onScrolled里面拿到最后一次看的item位置，然后在onScrollStateChanged里面判断是否要调用loadmore方法
public abstract class HugeRecyclerOnScrollListener extends RecyclerView.OnScrollListener {
private final static String TAG = HugeRecyclerOnScrollListener.class.getSimpleName();
// all item count by LayoutManager.getItemCount();
private int mTotalCount;
// visible item count by LayoutManager.getChildCount();
private int mVisibleCount;
// last visible position count by LayoutManager.findLastVisibleItemPosition()
private int mLastVisiblePosition;
public abstract void onLoadMore();
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
LinearLayoutManager layoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
mLastVisiblePosition = layoutManager.findLastVisibleItemPosition();
}
/**
* newState
*
* @param recyclerView the recycler view
* @param newState 0: 当前屏幕停止滚动；
* 1: 屏幕在滚动 且 用户仍在触碰或手指还在屏幕上；
* 2: 随用户的操作，屏幕上产生的惯性滑动；
*/
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
// get layout manager
RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
mVisibleCount = layoutManager.getChildCount();
mTotalCount = layoutManager.getItemCount();
// if scroll idle and only one item not visible load more
// (total count -2 <= last visible position)
if (mVisibleCount > 0
&& newState == RecyclerView.SCROLL_STATE_IDLE
&& mTotalCount - 2 <= mLastVisiblePosition) {
onLoadMore();
}
//Log.d(TAG, "mVisibleCount = " + mVisibleCount + ";mTotalCount = " +
// mTotalCount + ";mLastVisibleItemPosition = " + mLastVisiblePosition
// + ";newState=" + newState);
}
}
准备完毕，我们来用吧
我们在Module的build.gradle中引入
// huge recyclerview library
compile 'com.open:hugerecyclerview:1.0.2'
下面可以直接使用了：
Activity的Code大部分都类似，不过我增加了mHugeOnScrollListener和OnRefreshSuccess等refresh监听，依据load more的结果来控制footerview的显示
public class EndlessActivity extends BaseActivity implements IEndlessListener {
private static final String TAG = "EndlessActivity";
// hint text view
private TextView mHint;
// presenter of MVP
private EndlessPresenter mPresenter;
// adapter
private EndlessRecyclerAdapter mAdapter;
private RecyclerView mRecyclerView;
private HugeRecyclerOnScrollListener mHugeOnScrollListener;
protected EndlessFooterUtils mFooterUtil;
// all data account in server
private static final int TOTAL_SIZE = 64;
// each page size count
private static final int PAGE_SIZE = 10;
// current data for test
private int mCurrentNum = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
protected void initData() {
mPresenter = new EndlessPresenter();
mPresenter.setListener(this);
}
@Override
protected void initView(Bundle savedInstanceState) {
setContentView(R.layout.activity_endless);
mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);
LinearLayoutManager lm = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(lm);
mAdapter = new EndlessRecyclerAdapter(this);
mRecyclerView.setAdapter(mAdapter);
mFooterUtil = new EndlessFooterUtils(new EndlessFooterView(this));
// set scroll listener
mHugeOnScrollListener = new HugeRecyclerOnScrollListener() {
@Override
public void onLoadMore() {
EndlessFooterView.State state = mFooterUtil.getFooterViewState(mRecyclerView);
// still loading, do nothing
if (EndlessFooterView.State.Loading == state) {
Log.d(TAG, "still loading, now return");
return;
}
// no more data
if (mCurrentNum > TOTAL_SIZE) {
mFooterUtil.setEnd(mRecyclerView, PAGE_SIZE);
return;
}
refreshData();
}
};
// add scroll listener
mRecyclerView.addOnScrollListener(mHugeOnScrollListener);
mHint = (TextView) findViewById(R.id.tv_hint);
}
private void refreshData() {
if (!NetworkUtils.isConnected(EndlessActivity.this)) {
mFooterUtil.setError(mRecyclerView, PAGE_SIZE, mFooterClick);
Log.w(TAG, "net work no connected");
ToastUtils.INSTANCE.showToast(EndlessActivity.this, "net work no connected",
Toast.LENGTH_SHORT);
return;
}
// loading more data
mFooterUtil.setLoading(mRecyclerView, PAGE_SIZE);
mPresenter.refreshData();
}
@Override
protected void loadData() {
mPresenter.getData();
}
@Override
public void OnLoadStart() {
mHint.setText(getString(R.string.load_start));
}
@Override
public void OnLoadSuccess(List<SampleModel> data) {
mHint.setText(getString(R.string.load_success));
mAdapter.setData(data);
}
@Override
public void OnLoadFail(String error) {
mHint.setText(getString(R.string.load_fail) + error);
}
@Override
public void OnRefreshSuccess(List<SampleModel> data) {
mAdapter.addData(data);
mCurrentNum += data.size();
mFooterUtil.setNormal(mRecyclerView, PAGE_SIZE);
}
private View.OnClickListener mFooterClick = new View.OnClickListener() {
@Override
public void onClick(View v) {
refreshData();
}
};
@Override
public void OnRefreshFail(String error) {
mFooterUtil.setError(mRecyclerView, PAGE_SIZE, mFooterClick);
}
@Override
protected void onDestroy() {
super.onDestroy();
mPresenter.destroy();
}
}
更多使用方法请查看：hugerecyclerview
看看效果图
