android中listview分批加载数据

一时失言乱红尘 2022-08-06 14:05 243阅读 0赞

布局文件

单项布局文件listview\_item.xml

页脚footer.xml

<?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:id="@+id/c81_forthBar"
            android:layout_width="50dp"
        	android:layout_height="wrap_content"
             style="?android:attr/progressBarStyle" /> 
        <TextView android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center_vertical"
        android:textSize="20sp"
        android:text="@string/loading"
        />
    </LinearLayout>

主类

package cn.android.datapage;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import android.app.Activity;
    import android.os.Bundle;
    import android.os.Handler;
    import android.os.Message;
    import android.view.Menu;
    import android.view.View;
    import android.widget.AbsListView;
    import android.widget.AbsListView.OnScrollListener;
    import android.widget.ArrayAdapter;
    import android.widget.ListView;
    import cn.android.service.DataService;
    
    public class MainActivity extends Activity {
    	private ListView listView;
    	private List<String> data = new ArrayList<String>();
    	//每次获取多少条数据
    	private int number = 20;
    	//总共有几页
    	private int maxpage = 5;
    	//判断是否加载完成
    	private boolean loadfinish = true;
    	
    	private ArrayAdapter<String> adapter;
    	private View footer;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            //取得页脚
            footer = getLayoutInflater().inflate(R.layout.footer, null);
            
            listView = (ListView) findViewById(R.id.listView);
            //监听滚动事件
            listView.setOnScrollListener(new ScrollListener());
            //取得数据
            data.addAll(DataService.getData());
            //绑定数据
            adapter = new ArrayAdapter<String>(this, R.layout.listview_item, R.id.textView, data);
            listView.addFooterView(footer);
            listView.setAdapter(adapter);
            listView.removeFooterView(footer);
        }
        
        private final class ScrollListener implements OnScrollListener {
    		@Override
    		public void onScrollStateChanged(AbsListView view, int scrollState) {
    			// TODO Auto-generated method stub
    		}
    		//正在滚动时调用
    		@Override
    		public void onScroll(AbsListView view, int firstVisibleItem,
    				int visibleItemCount, int totalItemCount) {
    			int lastItemId = listView.getLastVisiblePosition();
    			//判断数据是否达到最后一条记录
    			if ((lastItemId + 1) == totalItemCount) {
    				if (totalItemCount > 0) {
    					//当前页
    					int currentpage = totalItemCount % number == 0 ? totalItemCount/number : totalItemCount/number + 1;
    					int nextpage = currentpage + 1;
    					if (nextpage < maxpage && loadfinish) {
    						loadfinish = false;
    						//添加页脚
    						listView.addFooterView(footer);
    						//线程异步加载数据
    						new Thread(new Runnable() {
    							@Override
    							public void run() {
    								try {
    									//创造网络延迟
    									Thread.sleep(3000);
    								} catch (InterruptedException e) {
    									e.printStackTrace();
    								}
    								List<String> result = DataService.getData();
    								//发送数据
    								handler.sendMessage(handler.obtainMessage(100, result));
    							}
    						}).start();
    					}
    				}
    			}
    		}
        }
        //通过handler对象来从子线程中获取数据
        Handler handler = new Handler(){
    		@Override
    		public void handleMessage(Message msg) {
    			//得到数据
    			data.addAll((List<String>) msg.obj);
    			//告诉listview更新数据了，要求显示
    			adapter.notifyDataSetChanged();
    			//删除页脚
    			if (listView.getFooterViewsCount() > 0)
    				listView.removeFooterView(footer);
    			loadfinish = true;
    		}
        };
        @Override
        public boolean onCreateOptionsMenu(Menu menu) {
            getMenuInflater().inflate(R.menu.main, menu);
            return true;
        }
        
    }

取数据的类

package cn.android.service;
    
    import java.util.ArrayList;
    import java.util.List;
    
    /**
     * 提供数据
     * @author Administrator
     *
     */
    public class DataService {
    	public static List<String> getData() {
    		List<String> data = new ArrayList<String>();
    		for (int i = 0; i < 22; i++) {
    			data.add("我就是数据"+i);
    		}
    		return data;
    	}
    }