android之下拉刷新（reflush）

package com.example.reflush;

import android.app.ListActivity;  
import android.os.Bundle;  
import android.util.Log;  
import android.view.Gravity;  
import android.view.View;  
import android.view.ViewGroup;  
import android.widget.AbsListView;  
import android.widget.BaseAdapter;  
import android.widget.LinearLayout;  
import android.widget.ListView;  
import android.widget.ProgressBar;  
import android.widget.TextView;  
import android.widget.Toast;  
import android.widget.AbsListView.OnScrollListener;  
import android.widget.LinearLayout.LayoutParams;  

public class MainActivity extends ListActivity implements OnScrollListener{
    private static final String TAG = "MainActivity";  
    private listViewAdapter adapter = new listViewAdapter();  
    ListView listView ;  
    private int lastItem = 0;  
    LinearLayout loadingLayout;  
    /**  
      * 设置布局显示属性  
      */  
        private LayoutParams mLayoutParams =new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,LinearLayout.LayoutParams.WRAP_CONTENT);  
        /**  
      * 设置布局显示目标最大化属性  
      */  
        private LayoutParams FFlayoutParams =new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT,LinearLayout.LayoutParams.FILL_PARENT);  
          
    private ProgressBar progressBar;  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
      super.onCreate(savedInstanceState);  
      Log.i(TAG, "onCreate(Bundle savedInstanceState)>>>>>>>>>>>>>>>" );  
         //线性布局  
      LinearLayout layout = new LinearLayout(this);  
        //设置布局 水平方向  
      layout.setOrientation(LinearLayout.HORIZONTAL);  
       //进度条  
      progressBar = new ProgressBar(this);  
       //进度条显示位置  
      progressBar.setPadding(0, 0, 15, 0);  
      //把进度条加入到layout中  
      layout.addView(progressBar, mLayoutParams);  
      //文本内容  
      TextView textView = new TextView(this);  
      textView.setText("加载中...");  
      textView.setGravity(Gravity.CENTER_VERTICAL);  
      //把文本加入到layout中  
      layout.addView(textView, FFlayoutParams);  
      //设置layout的重力方向，即对齐方式是  
      layout.setGravity(Gravity.CENTER);  
        
      //设置ListView的页脚layout  
      loadingLayout = new LinearLayout(this);  
      loadingLayout.addView(layout, mLayoutParams);  
      loadingLayout.setGravity(Gravity.CENTER);  
        
      //得到一个ListView用来显示条目  
      listView = getListView();  
      //添加到页脚显示  
      listView.addFooterView(loadingLayout);  
      //给ListView添加适配器  
      setListAdapter(adapter);  
      //给ListView注册滚动监听  
      listView.setOnScrollListener(this);  
    }  
    @Override  
    public void onScroll(AbsListView v, int firstVisibleItem,  
       int visibleItemCount, int totalItemCount) {  
      Log.i(TAG , "Scroll>>>first: " + firstVisibleItem + ", visible: " + visibleItemCount + ", total: " + totalItemCount);  
      lastItem = firstVisibleItem + visibleItemCount - 1;  
      Log.i(TAG , "Scroll>>>lastItem:" + lastItem);  
      //显示50条ListItem，即0-49，因为onScroll是在“滑动”执行过之后才触发，所以用adapter.count<=41作条件  
      if (adapter.count<=41) {  
       if (firstVisibleItem+visibleItemCount==totalItemCount) {  
        adapter.count += 10;  
        adapter.notifyDataSetChanged();  
        listView.setSelection(lastItem);  
        int currentPage=adapter.count/10;  
        Toast.makeText(getApplicationContext(), "第"+currentPage+"页", Toast.LENGTH_LONG).show();  
       }  
      }  
      else {  
        listView.removeFooterView(loadingLayout);   
      }  
        
        
    }  
    @Override  
    public void onScrollStateChanged(AbsListView v, int state) {  
      if (lastItem == adapter.count && state == OnScrollListener.SCROLL_STATE_IDLE) {  
       Log.i(TAG,"ScrollStateChanged>>>state:"+state+"lastItem:" + lastItem);  
       //显示50条ListItem，即0-49，因为onScrollStateChanged是在“拖动滑动”执行过之后才触发，所以用adapter.count<=41作条件  
       if (adapter.count<=41) {  
        adapter.count += 10;  
        adapter.notifyDataSetChanged();  
       }  
      
      }  
    }  
      /**  
       * 要用用于生成显示数据  
       * @author tomatos.to  
       *  
       */  
    class listViewAdapter extends BaseAdapter {  
      int count = 10;  
      public int getCount() {  
       Log.i(TAG, "getCount>>>count:" + count);  
       return count;  
      }  
      public Object getItem(int pos) {  
       Log.i(TAG, "getItem>>>pos:" + pos);  
       return pos;  
      }  
      public long getItemId(int pos) {  
       Log.i(TAG, "getItemId>>>ItemId:" + pos);  
       return pos;  
      }  
      public View getView(int pos, View v, ViewGroup p) {  
       Log.i(TAG, "getView>>>pos:" + pos);  
       TextView view;  
       if (v==null) {  
        view = new TextView(MainActivity.this);  
       }  
       else {  
        view=(TextView)v;  
       }  
       view.setText("ListItem " + pos);  
       view.setTextSize(20f);  
       view.setGravity(Gravity.CENTER);  
       view.setHeight(60);  
       return view;  
      }  
    }  
    
}