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);}