android--仿微博下拉刷新菜单

package com.example.test_weibo;

import android.content.Context;
import android.os.Handler;
import android.os.Message;
import android.text.Selection;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class TestListView extends ListView implements OnScrollListener{

      /**
     * 头部的控件内容
     * 可根据header布局文件适当扩展
     */
    //头部的textview
    private TextView refresh_TextView;
    //头部的高度
    private int mHeader_Heght;
    //头部的view
    private View header_View;

  /*
   * 工具成员变量
   *
   */
    
    //context 当前使用这个自定义的context
    private Context context;
    //inflate出实例的inflater
    private LayoutInflater inflater;
    
    /**
     * 一些状态的常量值
     * 另外可以 增加一些控件的属性值。如padding。
     */
    private final int WHILE_REFRESH = 3;
    private final int REFRESH_FINISHED = 4;
    private final int PREPARE_REFRESH = 5;
    private final int WHILE_SCROLLING = 1;
    private final int SCROLLING_IDLE =  2;
    private final int GO_TO_REFRESH = 6;
    private final int FINISH_REFRESH = 7;
    
    /*
     * 当前滚动的状态。
     */    
    private int mNowScroolState = SCROLL_STATE_IDLE;
    
    /**
     *  当前的更新状态
     */
    private int mNowRefreshState = PREPARE_REFRESH;
    
    /**
     * 当前的adapter
     */
    private ListAdapter adapter;
    //当前pulldownlistener
    private pullDownListener mPullDownListener;
    
    
    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg){
            
            switch (msg.what) {
            case GO_TO_REFRESH://更新操作
                setSelection(0);
                mNowRefreshState = WHILE_REFRESH;
                refresh_TextView.setText("更新中");
                //mPullDownListener.onRefresh();
                 /**
                  * 做一个模拟的读取数据的过程实际上应该调pulldownlistener的onRefresh函数
                  */
                new Thread(){
                    public void run(){
                        
                        try {
                            Thread.sleep(2000);
                            handler.sendEmptyMessage(FINISH_REFRESH);
                        } catch (InterruptedException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                         
                    }
                }.start();        
                
                break;
            case FINISH_REFRESH://结束更新时的ui操作。
                mNowRefreshState = PREPARE_REFRESH;
                reset_Header();
                //setSelection(1);
                break;
            default:
                break;
            }
            
        }
        
    };
    
    /**
     * 三个构造函数
     * @param context
     * @param attrs
     * @param defStyle
     */
    public TestListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        // TODO Auto-generated constructor stub
        init(context);
            // TODO Auto-generated constructor stub
        
        
    }
    
    
    public TestListView(Context context ,AttributeSet attrs) {
        // TODO Auto-generated constructor stub
        super(context, attrs );
           init(context);
            
            
    }
    
    public TestListView(Context context){
        super( context );
        
    }
    
    
    /**
     * 初始化头部控件
     * @param context
     */
    
    public void init(Context context){
        this.context = context;
        inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        header_View = inflater.inflate(R.layout.header, this,false);
        refresh_TextView = (TextView)header_View.findViewById(R.id.header);
        addHeaderView(header_View);
        super.setOnScrollListener(this);
        measureView(header_View);
        mHeader_Heght = header_View.getMeasuredHeight();
        System.out.println("fucking_pad"+header_View.getPaddingTop());
        System.out.println("height"+header_View.getMeasuredHeight());
        
       this.setVerticalScrollBarEnabled(false);//设置垂直的滚动条不出现
    }
    
    
    @Override
    public boolean onTouchEvent(MotionEvent event){
        
       switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN://当手指按下的时候把滚动状态设置为滚动中
        System.out.println("down");
        mNowScroolState = WHILE_SCROLLING;
        //Toast.makeText(context, "down", Toast.LENGTH_LONG).show();
        break;
    case MotionEvent.ACTION_MOVE://在移动的时候判断header的位置
        
        if(header_View.getBottom() > mHeader_Heght / 2 ){
            
            System.out.println("scroll_the_y"+event.getY());
            ready_For_Refresh();
        }
        
        if(header_View.getBottom() <= mHeader_Heght / 2 ){
            refresh_TextView.setText("下拉可更新");
        }
        
        System.out.println("header_height"+header_View.getHeight());
        System.out.println("header_top"+header_View.getTop());
        System.out.println("header_bottom"+header_View.getBottom());
        
        //Toast.makeText(context, "move", Toast.LENGTH_SHORT).show();
        setHeaderWhileFetching(event);
        break;
    case MotionEvent.ACTION_UP://手指抬起时将滚动状态设置为闲置。
        //判断是否从refresh
        //reset_Header();
        if(header_View.getBottom() > mHeader_Heght / 2){
            handler.sendEmptyMessage(GO_TO_REFRESH);
            
        }else{
            System.out.println("scroll_to_y"+mHeader_Heght);
            
            reset_Header();
        }
        mNowScroolState = SCROLL_STATE_IDLE;
        
        //Toast.makeText(context, "up", Toast.LENGTH_LONG).show();
        break;
    default://在其他情况将滚动状态为闲置状态。
        //判断是否refresh
        if(header_View.getBottom() < mHeader_Heght / 2){
            handler.sendEmptyMessage(GO_TO_REFRESH);
            //mNowRefreshState = WHILE_REFRESH;
        }else{
            System.out.println("scroll_to_y"+mHeader_Heght);
            
    
            
            reset_Header();
        }
        
        mNowScroolState = SCROLL_STATE_IDLE;
        
        break;
    }
        
        //回调原来的touchevent事件实现滚动
        return super.onTouchEvent(event);
    }

    /**
     * 重置头部view
     */
    public void reset_Header(){
        
        mNowRefreshState = PREPARE_REFRESH;
        refresh_TextView.setText("下拉更新");
        setSelection(1);
    }
    /**
     * 调整textview的文字
     */
    public void ready_For_Refresh(){
        refresh_TextView.setText("松开可更新");
    }
    
    /**
     * 没用的。。
     * @param event
     */
    public void setHeaderWhileFetching(MotionEvent event){
        
        int count = event.getHistorySize();
        float old_Y;
        for(int i = 0 ; i < count;++i){
           old_Y = event.getHistoricalY(i);
           System.out.println("old_Y"+old_Y);
        }
        float new_Y = event.getY();
        
        System.out.println( "new_Y  " + new_Y);
        
    }
    /**
     * 调用view的measure函数，计算出child的大小
     * @param child
     */
    private void measureView(View child) {
        ViewGroup.LayoutParams p = child.getLayoutParams();
        if (p == null) {
            p = new ViewGroup.LayoutParams(
                    ViewGroup.LayoutParams.FILL_PARENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT);
        }
        
        int childWidthSpec = ViewGroup.getChildMeasureSpec(0,0 + 0, p.width);
        int lpHeight = p.height;
        System.out.println("fucking"+lpHeight);
        int childHeightSpec;
        if (lpHeight > 0) {  
            childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight, MeasureSpec.EXACTLY);   
        } else {
            childHeightSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
        }
        child.measure(childWidthSpec, childHeightSpec);     
    }

    
    

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem,
            int visibleItemCount, int totalItemCount) {
        // TODO Auto-generated method stub
        System.out.println("first"+firstVisibleItem + visibleItemCount);
    }


    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
        // TODO Auto-generated method stub
        
    }
    /**
     * 设置适配器，并把头部view隐藏
     */
    @Override
    public void setAdapter(ListAdapter adapter){
        super.setAdapter(adapter);
        setSelection(1);
        
    }
    /**
     * this is the interface of listener to implement.
     * you can change the function inside to adapt to your needs.
     *
     * @author wang
     *
     */
    
    public interface pullDownListener{
        
        public void onRefresh();
        public void onMore();
        
    }
    
    /**
     * 设置下拉菜单
     * @param p
     */
    public  void setOnPullDownListener(pullDownListener p){
        this.mPullDownListener = p;
    }
    

}