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该控件继承Android标准的下拉刷新控件SwipeRefreshLayout，实现了RecyclerView的下拉刷新和上拉加载功能。
01 RecyclerRefreshLayout.java
public class RecyclerRefreshLayout extends SwipeRefreshLayout implements SwipeRefreshLayout.OnRefreshListener {
private RecyclerView mRecycleView;
private SuperRefreshLayoutListener listener;
private int mTouchSlop;
private boolean mIsOnLoading = false;
private boolean mCanLoadMore = true;
private int mDownY;
private int mMoveY;
public RecyclerRefreshLayout(Context context) {
this(context, null);
}
public RecyclerRefreshLayout(Context context, AttributeSet attrs) {
super(context, attrs);
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
setOnRefreshListener(this);
}
@Override
public void onRefresh() {
if (listener != null && !mIsOnLoading) {
listener.onRefreshing();
} else
setRefreshing(false);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
// 初始化ListView对象
if (mRecycleView == null) {
getRecycleView();
}
}
/**
* 获取RecyclerView
*/
private void getRecycleView() {
if (getChildCount() > 0) {
View childView = getChildAt(0);
if (!(childView instanceof RecyclerView)) {
childView = findViewById(R.id.recyclerView);
}
if (childView != null && childView instanceof RecyclerView) {
mRecycleView = (RecyclerView) childView;
mRecycleView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
if (canLoad() && mCanLoadMore) {
loadData();
}
}
});
}
}
}
@Override
public boolean dispatchTouchEvent(MotionEvent event) {
final int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
mDownY = (int) event.getRawY();
break;
case MotionEvent.ACTION_MOVE:
mMoveY = (int) event.getRawY();
break;
default:
break;
}
return super.dispatchTouchEvent(event);
}
/**
* 是否可以加载更多, 条件是到了最底部
*
* @return isCanLoad
*/
private boolean canLoad() {
return isScrollToBottom() && !mIsOnLoading && isPullUp();
}
/**
* 如果到了最底部,而且是上拉操作.那么执行onLoad方法
*/
private void loadData() {
if (listener != null) {
setOnLoading(true);
listener.onLoadMore();
}
}
/**
* 是否是上拉操作
*
* @return isPullUp
*/
private boolean isPullUp() {
return (mDownY - mMoveY) >= mTouchSlop;
}
/**
* 设置正在加载
*
* @param loading 设置正在加载
*/
public void setOnLoading(boolean loading) {
mIsOnLoading = loading;
if (!mIsOnLoading) {
mDownY = 0;
mMoveY = 0;
}
}
/**
* 判断是否到了最底部
*/
private boolean isScrollToBottom() {
return (mRecycleView != null && mRecycleView.getAdapter() != null)
&& getLastVisiblePosition() == (mRecycleView.getAdapter().getItemCount() - 1);
}
/**
* 刷新或加载结束记得调用
*/
public void setOnComplete() {
setOnLoading(false);
setRefreshing(false);
}
/**
* 是否可加载更多
*
* @param mCanLoadMore 是否可加载更多
*/
public void setCanLoadMore(boolean mCanLoadMore) {
this.mCanLoadMore = mCanLoadMore;
}
/**
* 获取RecyclerView可见的最后一项
*
* @return 可见的最后一项position
*/
public int getLastVisiblePosition() {
int position;
if (mRecycleView.getLayoutManager() instanceof LinearLayoutManager) {
position = ((LinearLayoutManager) mRecycleView.getLayoutManager()).findLastVisibleItemPosition();
} else if (mRecycleView.getLayoutManager() instanceof GridLayoutManager) {
position = ((GridLayoutManager) mRecycleView.getLayoutManager()).findLastVisibleItemPosition();
} else if (mRecycleView.getLayoutManager() instanceof StaggeredGridLayoutManager) {
StaggeredGridLayoutManager layoutManager = (StaggeredGridLayoutManager) mRecycleView.getLayoutManager();
int[] lastPositions = layoutManager.findLastVisibleItemPositions(new int[layoutManager.getSpanCount()]);
position = getMaxPosition(lastPositions);
} else {
position = mRecycleView.getLayoutManager().getItemCount() - 1;
}
return position;
}
/**
* 获得最大的位置
*
* @param positions 获得最大的位置
* @return 获得最大的位置
*/
private int getMaxPosition(int[] positions) {
int maxPosition = Integer.MIN_VALUE;
for (int position : positions) {
maxPosition = Math.max(maxPosition, position);
}
return maxPosition;
}
/**
* 添加加载和刷新
*
* @param listener add the listener for SuperRefreshLayout
*/
public void setSuperRefreshLayoutListener(SuperRefreshLayoutListener listener) {
this.listener = listener;
}
public interface SuperRefreshLayoutListener {
// 下拉刷新
void onRefreshing();
// 上拉加载
void onLoadMore();
}
}
02 layout中使用RecyclerRefreshLayout
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.rickge.learnbmob.widget.RecyclerRefreshLayout
android:id="@+id/recyclerRefreshLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/white">
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical"/>
</com.rickge.learnbmob.widget.RecyclerRefreshLayout>
</RelativeLayout>
03 代码控制RecyclerRefreshLayout
public class MainActivity extends AppCompatActivity implements RecyclerRefreshLayout.SuperRefreshLayoutListener{
private Context mContext;
RecyclerRefreshLayout mRecyclerRefreshLayout;
RecyclerView mRecyclerView;
TweetAdapter mAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mContext = this;
initWidget();
initData();
}
private void initData() {
mAdapter = new TweetAdapter(this);
mRecyclerView.setAdapter(mAdapter);
mRecyclerView.setLayoutManager(getLayoutManager());
mRecyclerRefreshLayout.setRefreshing(true);
getDataFromBmob(0);
}
private void initWidget() {
mRecyclerView = (RecyclerView) findViewById(R.id.recyclerView);
mRecyclerRefreshLayout = (RecyclerRefreshLayout) findViewById(R.id.recyclerRefreshLayout);
mRecyclerRefreshLayout.setProgressBackgroundColorSchemeResource(R.color.swipe_background_color);
mRecyclerRefreshLayout.setColorSchemeResources(R.color.swipe_color_1,
R.color.swipe_color_2,
R.color.swipe_color_3,
R.color.swipe_color_4);
mRecyclerRefreshLayout.setProgressViewEndTarget(true, 200);
//mRecyclerRefreshLayout.setSize(SwipeRefreshLayout.LARGE);
//mRecyclerRefreshLayout.setPadding(20, 20, 20, 20);
//mRecyclerRefreshLayout.setProgressViewOffset(true, 100, 200);
//mRecyclerRefreshLayout.setDistanceToTriggerSync(50);
mRecyclerRefreshLayout.setSuperRefreshLayoutListener(this);
}
private RecyclerView.LayoutManager getLayoutManager() {
return new LinearLayoutManager(mContext);
}
// 获取Bmob云存储数据
private void getDataFromBmob(final int newSkip){
if(newSkip != 0){
mAdapter.setState(TweetAdapter.STATE_LOADING);
}
BmobQuery<Tweet> query = new BmobQuery<>();
query.include("author");
query.order("-pubDate");
query.setSkip(newSkip);
query.setLimit(10);
query.findObjects(new FindListener<Tweet>() {
@Override
public void done(final List<Tweet> list, BmobException e) {
// 网络请求成功
if(e == null && list != null){
// 有新数据
if(list.size() > 0){
if(newSkip == 0){
mAdapter.clear();
}
mAdapter.addAll(list);
mAdapter.setState(TweetAdapter.STATE_HIDE);
mRecyclerRefreshLayout.setCanLoadMore(true);
mRecyclerRefreshLayout.setOnComplete();
}
// 没有数据
else{
mAdapter.setState(TweetAdapter.STATE_NO_MORE);
mRecyclerRefreshLayout.setCanLoadMore(false);
mRecyclerRefreshLayout.setOnComplete();
}
}
// 网络请求失败
else {
mAdapter.setState(TweetAdapter.STATE_LOAD_ERROR);
mRecyclerRefreshLayout.setOnComplete();
}
}
});
}
// 下拉刷新
@Override
public void onRefreshing() {
getDataFromBmob(0);
}
// 上拉加载
@Override
public void onLoadMore() {
getDataFromBmob(mAdapter.getItemCount());
}
}
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