listview滚动到底部自动加载数据

ゝ一纸荒年。 2022-06-02 11:59 295阅读 0赞

文章转自：[http://blog.csdn.net/coderinchina/article/details/40188295][http_blog.csdn.net_coderinchina_article_details_40188295]

在android中listvieww加载数据,有的是分批加载,比如每次加载20条,100条就要加载5次,如果一次性加载100条,listview加载就变的慢,如果是有图片的话,一时浪费流量,二是item中带图片会出现错位的问题,listview加载数据目前好多app做法

1.  分批加载 滑动到底部自动更新
2.  滑动到底部 手动的点击加载更多
3.  下拉刷新+底部加载更多

今天就讲下listview滑动到底部自动更新

分析：监听listview的滑动事件,判断listview是否滑动到底部,然后去加载数据

代码如下：

public class MainActivity extends Activity {   
        private ListView listview;  
        private List<String> datas;  
        private LayoutInflater inflater;  
        private MyAdapter adapter;  
        private List<String>  contents;  
        private int count = 0;  
        private View footView;  
        private Handler handler = new Handler();  
        int lastItem;  
        private RelativeLayout loading;  
        @Override  
        protected void onCreate(Bundle savedInstanceState) {  
            super.onCreate(savedInstanceState);  
            setContentView(R.layout.activity_main);  
            initData();  
            inflater = LayoutInflater.from(this);  
            listview = (ListView) findViewById(R.id.listview);  
            adapter = new MyAdapter();  
            footView = inflater.inflate(R.layout.footer, null);  
            loading = (RelativeLayout) footView.findViewById(R.id.loading);  
            //listview的addFooterView()添加view到listview底部一定要加在listview.setAdapter(adapter);这代码前面 
            listview.addFooterView(footView);  
            listview.setAdapter(adapter);  
            //添加listview滚动监听 
            listview.setOnScrollListener(new OnScrollListener() {  
                //AbsListView view 这个view对象就是listview 
                @Override  
                public void onScrollStateChanged(AbsListView view, int scrollState) {  
                    if (scrollState == OnScrollListener.SCROLL_STATE_IDLE) {  
                        if (view.getLastVisiblePosition() == view.getCount() - 1) {  
                            loadData();  
                        }  
                    }  
                }  
                @Override  
                public void onScroll(AbsListView view, int firstVisibleItem,  
                        int visibleItemCount, int totalItemCount) {  
                       lastItem = firstVisibleItem + visibleItemCount - 1 ;  
                }  
            });  
        }  
        protected void loadData() {  
            loading.setVisibility(View.VISIBLE);  
            handler.postDelayed(new Runnable() {  
                @Override  
                public void run() {  
                     load();  
                     loading.setVisibility(View.GONE);  
                     adapter.notifyDataSetChanged();  
                }  
            }, 5000);  
        }  
        protected void load() {  
            int count=adapter.getCount()+1;  
            for(int i=count;i<count+20;i++){  
                 contents.add("加载数据:::"+i);  
            }  
        }  
        private void initData() {  
            contents = new ArrayList<String>();  
            for(int i=1;i<20;i++){  
                contents.add("加载数据:::"+i);  
            }  
        }  
    
        class MyAdapter extends BaseAdapter{  
            @Override  
            public int getCount() {  
                return contents.size();  
            }  
            @Override  
            public Object getItem(int position) {  
                return contents.get(position);  
            }  
    
            @Override  
            public long getItemId(int position) {  
                return position;  
            }  
    
            @Override  
            public View getView(int position, View convertView, ViewGroup parent) {  
                ViewHolder holder;  
                if(convertView==null){  
                    convertView = inflater.inflate(R.layout.item, parent, false);  
                    holder = new ViewHolder();  
                    holder.tvContent = (TextView) convertView.findViewById(R.id.tvContent);  
                    convertView.setTag(holder);  
                }else{  
                    holder = (ViewHolder) convertView.getTag();  
                }  
                holder.tvContent.setText(contents.get(position));  
                return convertView;  
            }  
            class ViewHolder{  
                TextView tvContent;  
            }  
        }  
    }

[http_blog.csdn.net_coderinchina_article_details_40188295]: http://blog.csdn.net/coderinchina/article/details/40188295