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 = ;
    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(, , , );
      //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 - ;
      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<=) {
       if (firstVisibleItem+visibleItemCount==totalItemCount) {
        adapter.count += ;
        adapter.notifyDataSetChanged();
        listView.setSelection(lastItem);
        int currentPage=adapter.count/;
        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<=) {
        adapter.count += ;
        adapter.notifyDataSetChanged();
       }  

      }
    }
      /**
       * 要用用于生成显示数据
       * @author tomatos.to
       *
       */
    class listViewAdapter extends BaseAdapter {
      int count = ;
      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();
       return view;
      }
    }  

}