Android- 分页加载显示数据（上拉加载，下拉刷新）
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1. 自定义布局 pull_recycle_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.v4.widget.SwipeRefreshLayout
android:id="@+id/swipeRefreshLayout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:id="@+id/footerView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:gravity="center"
android:orientation="horizontal"
android:visibility="gone">
<ProgressBar
style="@android:style/Widget.DeviceDefault.Light.ProgressBar"
android:layout_width="wrap_content"
android:layout_height="28dp"
android:layout_marginRight="10dp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingBottom="10dp"
android:paddingTop="10dp"
android:text="@string/loading" />
</LinearLayout>
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="@+id/footerView" />
</RelativeLayout>
</android.support.v4.widget.SwipeRefreshLayout>
</LinearLayout>
AI写代码2. 自定义刷新控件 PullRecyclerView.java
package com.sfnp.warehouse.widget;
import android.content.Context;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.widget.LinearLayout;
import com.sfnp.warehouse.R;
public class PullRecyclerView extends LinearLayout implements SwipeRefreshLayout.OnRefreshListener, View.OnTouchListener {
private SwipeRefreshLayout swipeRefreshLayout;
private RecyclerView recyclerView;
private LinearLayout footerView;
private OnPullRefreshListener listener;
//是否正在刷新
private boolean isRefreshing = false;
//是否正在加载
private boolean isLoading = false;
//是否有更多数据
private boolean hasMore = false;
public PullRecyclerView(Context context) {
this(context, null);
}
public PullRecyclerView(Context context, AttributeSet attrs) {
super(context, attrs);
initView(context);
initListener();
init();
}
private void initView(Context context) {
LayoutInflater.from(context).inflate(R.layout.pull_recycler_layout, this, true);
swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipeRefreshLayout);
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
footerView = (LinearLayout) findViewById(R.id.footerView);
}
private void initListener() {
swipeRefreshLayout.setOnRefreshListener(this);
recyclerView.addOnScrollListener(new PullableScroll());
//防止滚动的时候，滑动View
recyclerView.setOnTouchListener(this);
}
private void init() {
swipeRefreshLayout.setColorSchemeResources(android.R.color.holo_green_dark,
android.R.color.holo_blue_dark,
android.R.color.holo_orange_dark);
//隐藏垂直滚动条
recyclerView.setVerticalScrollBarEnabled(true);
//item高度固定时，设置该选项提高性能
recyclerView.setHasFixedSize(true);
//设置item动画效果
recyclerView.setItemAnimator(new DefaultItemAnimator());
}
public void setHasFixedSize(boolean hasFixedSize) {
recyclerView.setHasFixedSize(hasFixedSize);
}
public void setItemAnimator(RecyclerView.ItemAnimator animator) {
recyclerView.setItemAnimator(animator);
}
public void setLayoutManager(RecyclerView.LayoutManager layout) {
recyclerView.setLayoutManager(layout);
}
public void setVerticalScrollBarEnabled(boolean verticalScrollBarEnabled) {
recyclerView.setVerticalScrollBarEnabled(verticalScrollBarEnabled);
}
public void addItemDecoration(RecyclerView.ItemDecoration decor) {
recyclerView.addItemDecoration(decor);
}
public void setAdapter(RecyclerView.Adapter adapter) {
recyclerView.setAdapter(adapter);
}
/** * 设置监听下拉或上拉的事件
* * @param listener
*/
public void setOnPullRefreshListener(OnPullRefreshListener listener) {
this.listener = listener;
}
/** * 设置是否有更多数据
* * @param hasMore
*/
public void setHasMore(boolean hasMore) {
this.hasMore = hasMore;
}
/** * 滚动到顶部
*/
public void scrollToTop() {
recyclerView.scrollToPosition(0);
}
/** * 正在刷新
*/
@Override
public void onRefresh() {
isRefreshing = true;
if (listener != null) {
listener.onRefresh();
}
}
/** * 设置是否允许下拉
* * @param enable
*/
public void setRefreshEnable(boolean enable) {
swipeRefreshLayout.setEnabled(enable);
}
/** * 滚动时判断能否能刷新
* * @return
*/
private boolean isRefreshEnable() {
return !isRefreshing && !isLoading;
}
/** * 正在加载更多
*/
public void doLoadMore() {
if (!isLoading && hasMore && !isRefreshing) {
footerView.setVisibility(View.VISIBLE);
isLoading = true;
//禁止下拉
setRefreshEnable(false);
if (listener != null) {
listener.onLoadMore();
}
}
}
/** * 刷新或加载完成
*/
public void refreshOrLoadComplete() {
isRefreshing = false;
swipeRefreshLayout.setRefreshing(false);
isLoading = false;
footerView.setVisibility(View.GONE);
//允许下拉
this.setEnabled(true);
}
@Override
public boolean onTouch(View v, MotionEvent event) {
return isRefreshing || isLoading;
}
public interface OnPullRefreshListener {
/** * 刷新操作
*/
void onRefresh();
/** * 加载操作
*/
void onLoadMore();
}
/** * 监听RecycleView滑动底部或顶部
*/
class PullableScroll extends RecyclerView.OnScrollListener {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
int lastVisibleItem = 0;
int firstVisibleItem = 0;
RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
int totalItemCount = layoutManager.getItemCount();
if (layoutManager instanceof LinearLayoutManager) {
LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
firstVisibleItem = linearLayoutManager.findFirstCompletelyVisibleItemPosition();
} else if (layoutManager instanceof StaggeredGridLayoutManager) {
StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
// since may lead to the final item has more than one StaggeredGridLayoutManager the particularity of the so here that is an array
// this array into an array of position and then take the maximum value that is the last show the position value
int[] lastPositions = new int[((StaggeredGridLayoutManager) layoutManager).getSpanCount()];
staggeredGridLayoutManager.findLastVisibleItemPositions(lastPositions);
lastVisibleItem = findMax(lastPositions);
firstVisibleItem = staggeredGridLayoutManager.findFirstVisibleItemPositions(lastPositions)[0];
}
pullRefreshEnable(firstVisibleItem, totalItemCount);
if (isSlideToBottom(recyclerView)) {
loadMore(dx, dy, lastVisibleItem, totalItemCount);
}
}
private int findMax(int[] lastPositions) {
int max = lastPositions[0];
for (int value : lastPositions) {
if (value > max) {
max = value;
}
}
return max;
}
}
/** * 判断是否滑动到底部
* * @param recyclerView
* @return
*/
public boolean isSlideToBottom(RecyclerView recyclerView) {
if (recyclerView == null) {
return false;
}
if (recyclerView.computeVerticalScrollExtent() + recyclerView.computeVerticalScrollOffset()
>= recyclerView.computeVerticalScrollRange()) {
return true;
}
return false;
}
private void loadMore(int dx, int dy, int lastVisibleItem, int totalItemCount) {
//滚动到底部时且有更多数据能够上拉加载
if (lastVisibleItem >= totalItemCount - 1 && (dx > 0 || dy > 0)) {
doLoadMore();
}
}
private void pullRefreshEnable(int firstVisibleItem, int totalItemCount) {
//滚动到顶部时能够下拉刷新
if (firstVisibleItem == 0 || totalItemCount == 0) {
if (isRefreshEnable()) {
//允许下拉
setRefreshEnable(true);
}
} else {
//禁止下拉
setRefreshEnable(false);
}
}
}
AI写代码3. 在应用类中，实现 PullRecyclerView.OnPullRefreshListener
部分核心代码如下：
public class CategoryExceptionActivity implementsPullRecyclerView.OnPullRefreshListener {
private static final int CURRENT_PAGE = 1;
private static final int PAGE_SIZE = 6;//一般一页的数目大于屏幕的显示
private int mCurrentPage = CURRENT_PAGE;
private int mPageSize = PAGE_SIZE;
//拉取数据，显示的总体列表
private List<DetainListRes> detainList;
@Override
public void onRefresh() {
detainList.clear();
mCurrentPage = CURRENT_PAGE;
getPage();//请求数据
}
@Override
public void onLoadMore() {
++mCurrentPage;
getPage();
}
}
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