ListView 上拉加载更多

ListView 上拉加载更多

首先来个效果图

界面布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_list_view_refresh"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.it.controlstudy.ListViewRefreshActivity">
<ListView
    android:id="@+id/listviewrefresh_lv"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</ListView>
</RelativeLayout>

ListView Item

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="horizontal"
              android:layout_width="match_parent"
              android:layout_height="match_parent">
<ImageView
    android:id="@+id/listviewrefrsh_item_iv"
    android:background="@drawable/img2"
    android:layout_marginLeft="30dp"
    android:layout_marginTop="10dp"
    android:layout_marginBottom="10dp"
    android:layout_width="80dp"
    android:layout_height="80dp"/>
    <TextView
        android:id="@+id/listviewrefrsh_item_tv"
        android:text="This is a computer!"
        android:layout_marginTop="30dp"
        android:textSize="20dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
</LinearLayout>

Load More 视图

<?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="horizontal">

    <ProgressBar
        android:layout_marginLeft="60dp"
        android:layout_marginTop="10dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <TextView
        android:text="Load more ..."
        android:textSize="20dp"
        android:layout_marginTop="20dp"
        android:layout_marginLeft="20dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
</LinearLayout>

Activity

public class ListViewRefreshActivity extends AppCompatActivity  {

    public ListView listView;
    public View loadmoreView;
    public int last_index; //当前页面最下方ListView Item在adapter中的位置
    public int total_index; //所有ListView的Item总个数
    public List<String> list = new ArrayList<>();// 数据集合
    public MyBaseAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_list_view_refresh);

        listView = (ListView) findViewById(R.id.listviewrefresh_lv);

        // 获得自定义的刷新视图
        loadmoreView= View.inflate(ListViewRefreshActivity.this,R.layout.listviewrefresh_loadmore_layout,null);
       // 设置刷新视图默认情况下是不可见的,并且不占空间
        loadmoreView.setVisibility(View.GONE);
        // 添加刷新视图到ListView中
        listView.addFooterView(loadmoreView,null,false);

        //初始化集合数据
        for (int i = 1; i <= 10; i++) {
            list.add("I am the "+i+" computer!");
        }

        //为ListView设置adapter
        adapter = new MyBaseAdapter(this, list);
        listView.setAdapter(adapter);

        //设置ListView的监听事件
        listView.setOnScrollListener(new AbsListView.OnScrollListener() {
            /**
             * 监听着ListView的滑动状态改变。
             * 一共有三种状态
             * SCROLL_STATE_TOUCH_SCROLL：手指正拖着ListView滑动
             * SCROLL_STATE_FLING：ListView自由滑动
             * SCROLL_STATE_IDLE：ListView滑动后静止
             * */
            @Override
            public void onScrollStateChanged(AbsListView absListView, int scrollState) {

                //ListView 处于最下方，并且滑动停止
                if(last_index == total_index && (scrollState == AbsListView.OnScrollListener.SCROLL_STATE_IDLE))
                {
                    //设置刷新界面可见
                    loadmoreView.setVisibility(View.VISIBLE);
                    //加载更多数据
                    onLoad();
                }
            }

            /**
             * firstVisibleItem: 屏幕中显示的第一个Item数据在adapter中的位置
             * visibleItemCount：屏幕中显示Item的个数
             * totalItemCount: 在adapter中的总Item数
             * */
            @Override
            public void onScroll(AbsListView absListView, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
                //计算最后一个Item位置，最后根据这个值判断是否到达ListView最下方
                last_index = firstVisibleItem+visibleItemCount;
                total_index = totalItemCount;

                System.out.println("last:  "+last_index);
                System.out.println("total:  "+total_index);
            }

        });
    }

    /**
     * 加载更多数据
     */
    public void onLoad()
    {
        new Thread(new Runnable() {
            @Override
            public void run() {

                try {
                    //模拟耗时操作
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                //向数据集中添加数据
                for (int i = 0; i < 10; i++) {
                    list.add("I am the "+(list.size()+1)+" computer!");
                }
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {

                        //刷新ListView
                        adapter.updateView(list);

                        //加载数据结束后使刷新界面不可见
                        loadmoreView.setVisibility(View.GONE);
                    }
                });

            }
        }).start();

    }

    class MyBaseAdapter extends BaseAdapter{

        public List<String> list;
        public LayoutInflater inflater;

        public MyBaseAdapter(Context context, List<String> list) {
            this.list=list;
            this.inflater=LayoutInflater.from(context);
        }

        @Override
        public int getCount() {
            return list.size();
        }

        @Override
        public Object getItem(int i) {
            return list.get(i);
        }

        @Override
        public long getItemId(int i) {
            return 0;
        }

        public void updateView(List<String> nowList){
            this.list=nowList;
            this.notifyDataSetChanged(); //强制动态刷新数据进而调用getView方法
        }

        @Override
        public View getView(int i, View view, ViewGroup viewGroup) {
            ViewHolder viewHoder;
            if(view ==null){
                viewHoder=new ViewHolder();
                view=inflater.inflate(R.layout.listviewrefresh_item_layout,null);

                viewHoder.imageView=(ImageView) view.findViewById(R.id.listviewrefrsh_item_iv);
                viewHoder.textView=(TextView) view.findViewById(R.id.listviewrefrsh_item_tv);
                view.setTag(viewHoder);

            }else {
                viewHoder=(ViewHolder)view.getTag();
            }

            viewHoder.textView.setText(list.get(i));

            return view;
        }
        class  ViewHolder{
            ImageView imageView;
            TextView textView;
        }
    }
}