ListView 加载更多列表 Load More mono forandroid 项目笔记

浏览数：16 / 时间：2015年06月11日

今天项目经理找我说Listview加载更多的时候会出现一些问题，主要表现在会顿一下。让我我就去找Java的方法看看。自己写出了mono 的加载更多功能。和大家分享一下

先看效果

首先是模型类ListItem

public class ListItem
    {
        public  string item{ get;set;}
    }

然后是数据适配器类

//数据适配器类
    public class ListViewAdapter:ArrayAdapter<ListItem>
    {
        public ListViewAdapter(Context context): base(context, 0)
        { }

         public override View  GetView(int position, View convertView, ViewGroup parent)
        {
            View view;
            if (convertView !=null)
            {
                view = convertView;
             }
            else
            {
                view = LayoutInflater.From(this.Context).Inflate(Resource.Layout.listItem, null);
            }

            TextView tv = view.FindViewById<TextView>(Resource.Id.Itemstring);

            ListItem it = GetItem(position);
            tv.Text = it.item;
             return view;
         }

    }

最后是创建主界面

public class Activity1 : Activity
    {

        public ListView listview;
        public int visibleLastIndex = 0;   //最后的可视项索引   
        public int visibleItemCount;       // 当前窗口可见项总数   
        public View loadMoreView;          //更多视图
        public ListViewAdapter adapter;   //数据适配器
        private Handler handler = new Handler();    
        List<ListItem> items = new List<ListItem>();
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.Main);
            //在listview 后面加载更多是视图
            loadMoreView = LayoutInflater.Inflate(Resource.Layout.Main,null);

            listview = FindViewById<ListView>(Resource.Id.listview);

            adapter = new ListViewAdapter(this);
            //初始化
            initAdapter();

            listview.Adapter = adapter;
            
            listview.ScrollStateChanged += new EventHandler<AbsListView.ScrollStateChangedEventArgs>(listview_ScrollStateChanged);
            //loadMoreButton.Click += new EventHandler(loadMoreButton_Click);
            //在原有Listview的后面加上加载来的数据数据
            listview.AddFooterView(loadMoreView);
        }
        //
        void loadMoreClick()
        {
            //开启java 多线程加载更多
            //开启委托
            Action ac = new Action(getMore);
            //runnable 只提供这一种构造方法……
            handler.PostDelayed(new Runnable(ac){}, 1000);
        }
        //加载更多初始化方法
        void getMore()
        {
            LoadData();
            adapter.NotifyDataSetChanged();//数据集变化后,通知adapter 
            listview.SetSelection(visibleLastIndex - visibleItemCount + 1);//设置选中项 
        }
        //加载更多获取数据方法
        void LoadData()
        {
            int count = adapter.Count;
            for (int i = 0; i < count+12; i++)
            {
                ListItem item = new ListItem();
                item.item = i + "呵呵"+ i;
                items.Add(item);
                adapter.Add(item);
               
            }
            
        }
        //滚动状态改变是发生
        void listview_ScrollStateChanged(object sender, AbsListView.ScrollStateChangedEventArgs e)
        {
            ListView lv = sender as ListView;
            this.visibleItemCount = lv.LastVisiblePosition - lv.FirstVisiblePosition;//当前窗口可见项总数
            visibleLastIndex = lv.LastVisiblePosition+1; //最后可视索引

            int itemsLastIndex = adapter.Count-1; //数据集最后一项的索引  
            int lastIndex = itemsLastIndex +1;     //加上底部的loadMoreView项   

            if (ScrollState.Idle == e.ScrollState && visibleLastIndex == lastIndex)
            {
                //如果自动加载，可以异步加载
                loadMoreClick();
            }

        }


        //初始化适配器
        private void initAdapter()
        {
            for (int i = 0; i < 15; i++)
            {
                ListItem item = new ListItem();
                item.item = i+"哈哈哈"+i;
                items.Add(item);
                adapter.Add(item);
            }
        }
    }