Android代码实现AdapterViews和RecyclerView无限滚动

package com.codepath.customadapter;import android.widget.AbsListView;/** * Created by Administrator on 2016/7/11. */public abstract class EndlessScrollListener implements AbsListView.OnScrollListener { //在你滑动项下最少为多少时开始加载数据 private int visibleThreshold = 5; //已经加载数据的当前页码 private int currentPage = 0; //上一次加载数据后数据库的数据量 private int previousTotalItemCount = 0; //我们是否在等待最后一组数据的加载 private boolean loading = true; //设置开始页的下标 private int startingPageIndex = 0; public EndlessScrollListener() { } public EndlessScrollListener(int visibleThreshold) {  this.visibleThreshold = visibleThreshold; } public EndlessScrollListener(int visibleThreshold, int startingPageIndex) {  this.visibleThreshold = visibleThreshold;  this.startingPageIndex = startingPageIndex; } //这个方法可能会在滑动调用很多次，所以在设计时要保持谨慎 //我们需要一些有用的参数来帮助我们，当我们需要加载更多数据的时候 //但是我们首先要检查是否我们在等待先前的加载结束//onScroll()当列表或网格视图被滚动后将会调用，参数一：报告状态的视图参数二：第一个可以看见的项的下标，参数三：可见项的数量参数四：listAdapter中所有的项数 @Override public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {  //如果总项数为0，而且先前没有项，那么这个列表是无效的应该被设定为初始状态  if (totalItemCount < previousTotalItemCount) {   this.currentPage = this.startingPageIndex;   this.previousTotalItemCount = totalItemCount;   if (totalItemCount == 0) {this.loading = true;}  }  //如果仍在加载中我们可以检查一下数据集合是否改变了，如果改变的话那就是已经完成了loading需要更新当前  //页数和数据总量  if (loading && (totalItemCount > previousTotalItemCount)) {   loading = false;   previousTotalItemCount = totalItemCount;   currentPage++;  }  //如果当前没有加载，我们需要检查当前是否达到了阈值，如果是的话我们需要  //加载更多的数据，执行onLoadMore  if (!loading && (firstVisibleItem + visibleItemCount + visibleThreshold) >= totalItemCount) {   loading = onLoadMore(currentPage + 1, totalItemCount);  } } //定义实际加载数据的过程，如果数据加载完成返回false，如果正在加载返回true； public abstract boolean onLoadMore(int page, int totalItemCount); @Override public void onScrollStateChanged(AbsListView view, int scrollState) {  //不采取动作 }}

public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstance) {  //向平常一样   ListView lvItems = (ListView) findViewById(R.id.lvItens);   //将监听器绑定到上面    lvItems.setOnScrollListener(new EndlessScrollListener() {   @Override   public boolean onLoadMore(int page, int totalItemsCount) {    // 当新数据需要绑定到列表上的时候触发    // 加载数据需要的代码Add whatever code is needed to append new items to your AdapterView    customLoadMoreDataFromApi(page);     // or customLoadMoreDataFromApi(totalItemsCount);     return true; //数据加载中为true，不然为false； ONLY if more data is actually being loaded; false otherwise.   }  }); } //加载更多的数据 public void customLoadMoreDataFromApi(int offset) {  //这个方法通常会发起一些网络请求，然后向适配器添加更多的数据  //将偏移量数据作为参数附在请求里来获得一个数据的分页  //解析API返回的值并且获得新的对象构建适配器 }}

 protected void onCreate(Bundle savedInstanceState) {  // Configure the RecyclerView获得RecylerView的实例  RecyclerView rvItems = (RecyclerView) findViewById(R.id.rvContacts);  LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);  recyclerView.setLayoutManager(linearLayoutManager);  // Add the scroll listener  rvItems.addOnScrollListener(new EndlessRecyclerViewScrollListener(linearLayoutManager) {   @Override   public void onLoadMore(int page, int totalItemsCount) {    // Triggered only when new data needs to be appended to the list    // Add whatever code is needed to append new items to the bottom of the list    customLoadMoreDataFromApi(page);    }  }); } // Append more data into the adapter // This method probably sends out a network request and appends new data items to your adapter.  public void customLoadMoreDataFromApi(int page) {  // Send an API request to retrieve appropriate data using the offset value as a parameter.  // --> Deserialize API response and then construct new objects to append to the adapter  // --> Notify the adapter of the changes }}

public abstract class EndlessRecyclerViewScrollListener extends RecyclerView.OnScrollListener { // The minimum amount of items to have below your current scroll position // before loading more. private int visibleThreshold = 5; // The current offset index of data you have loaded private int currentPage = 0; // The total number of items in the dataset after the last load private int previousTotalItemCount = 0; // True if we are still waiting for the last set of data to load. private boolean loading = true; // Sets the starting page index private int startingPageIndex = 0; RecyclerView.LayoutManager mLayoutManager; public EndlessRecyclerViewScrollListener(LinearLayoutManager layoutManager) {  this.mLayoutManager = layoutManager; } public EndlessRecyclerViewScrollListener(GridLayoutManager layoutManager) {  this.mLayoutManager = layoutManager;  visibleThreshold = visibleThreshold * layoutManager.getSpanCount(); } public EndlessRecyclerViewScrollListener(StaggeredGridLayoutManager layoutManager) {  this.mLayoutManager = layoutManager;  visibleThreshold = visibleThreshold * layoutManager.getSpanCount(); } public int getLastVisibleItem(int[] lastVisibleItemPositions) {  int maxSize = 0;  for (int i = 0; i < lastVisibleItemPositions.length; i++) {   if (i == 0) {    maxSize = lastVisibleItemPositions[i];   }   else if (lastVisibleItemPositions[i] > maxSize) {    maxSize = lastVisibleItemPositions[i];   }  }  return maxSize; } // This happens many times a second during a scroll, so be wary of the code you place here. // We are given a few useful parameters to help us work out if we need to load some more data, // but first we check if we are waiting for the previous load to finish. @Override public void onScrolled(RecyclerView view, int dx, int dy) {  int lastVisibleItemPosition = 0;  int totalItemCount = mLayoutManager.getItemCount();  if (mLayoutManager instanceof StaggeredGridLayoutManager) {   int[] lastVisibleItemPositions = ((StaggeredGridLayoutManager) mLayoutManager).findLastVisibleItemPositions(null);   // get maximum element within the list   lastVisibleItemPosition = getLastVisibleItem(lastVisibleItemPositions);  } else if (mLayoutManager instanceof LinearLayoutManager) {   lastVisibleItemPosition = ((LinearLayoutManager) mLayoutManager).findLastVisibleItemPosition();  } else if (mLayoutManager instanceof GridLayoutManager) {   lastVisibleItemPosition = ((GridLayoutManager) mLayoutManager).findLastVisibleItemPosition();  }  // If the total item count is zero and the previous isn't, assume the  // list is invalidated and should be reset back to initial state  if (totalItemCount < previousTotalItemCount) {   this.currentPage = this.startingPageIndex;   this.previousTotalItemCount = totalItemCount;   if (totalItemCount == 0) {    this.loading = true;   }  }  // If it's still loading, we check to see if the dataset count has  // changed, if so we conclude it has finished loading and update the current page  // number and total item count.  if (loading && (totalItemCount > previousTotalItemCount)) {   loading = false;   previousTotalItemCount = totalItemCount;  }  // If it isn't currently loading, we check to see if we have breached  // the visibleThreshold and need to reload more data.  // If we do need to reload some more data, we execute onLoadMore to fetch the data.  // threshold should reflect how many total columns there are too  if (!loading && (lastVisibleItemPosition + visibleThreshold) > totalItemCount) {   currentPage++;   onLoadMore(currentPage, totalItemCount);   loading = true;  } } // Defines the process for actually loading more data based on page public abstract void onLoadMore(int page, int totalItemsCount);}