android ListView下拉刷新之功能实现

首先要知道刷新有三个状态，

1是下拉中

2是松开刷新

3是正在刷新

还有一个非常重要的是回调接口，这个接口是正在刷新的时候外界需要做的事。

然后外界再把状态重置。

回调接口需要三个属性，

    private OnRefLisner listener;

    public void setOnRefLisner(OnRefLisner listener){
        this.listener = listener;
    }

    //回调接口
    public interface OnRefLisner{
        void setPullRfe();
    }

package com.example.listviewf5;

import java.text.SimpleDateFormat;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.RotateAnimation;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.TextView;

public class MyListView extends ListView {
    private View v;
    private int headHeight;// 头部的高度
    private int downY;// 按下时候Y坐标

    private final int PULL_REF = 0;// 下拉
    private final int REL_REF = 1;// 松开刷新
    private final int REFING = 2;// 刷新中
    private int currentState = PULL_REF;

    private TextView tv;
    private TextView tvtiem;
    private ImageView img;
    private ProgressBar pb;
    //旋转动画
    private RotateAnimation upAnimation,downAnimation;

    public MyListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        // TODO Auto-generated constructor stub
        initView(context);
    }

    public MyListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
        initView(context);
    }

    public MyListView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
        initView(context);
    }

    /**
     * 加载顶部布局文件
     * 
     * @param context
     */
    private void initView(Context context) {
        // LayoutInflater in =LayoutInflater.from(context);
        // v = in.inflate(R.layout.head,null);
        v = View.inflate(context, R.layout.head, null);
        this.addHeaderView(v);
        v.measure(0, 0);// 通知系统测量宽高
        headHeight = v.getMeasuredHeight();// 得到测量后的高度
        v.setPadding(0, -headHeight, 0, 0);// 进行隐藏head,就是把paddingtop设置成负高度

        tv = (TextView) v.findViewById(R.id.head_tv);
        tvtiem = (TextView) v.findViewById(R.id.head_tvtime);
        img = (ImageView) v.findViewById(R.id.head_img);
        pb = (ProgressBar) v.findViewById(R.id.pb);
        initHeadRotateAnimation();
        
    }

    private void initHeadRotateAnimation() {
        upAnimation = new RotateAnimation(0, -180, 
                RotateAnimation.RELATIVE_TO_SELF, 0.5f,
                RotateAnimation.RELATIVE_TO_SELF, 0.5f);
        upAnimation.setDuration(300);
        upAnimation.setFillAfter(true);
        downAnimation = new RotateAnimation(-180, -360, 
                RotateAnimation.RELATIVE_TO_SELF, 0.5f,
                RotateAnimation.RELATIVE_TO_SELF, 0.5f);
        downAnimation.setDuration(300);
        downAnimation.setFillAfter(true);
        
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        switch (ev.getAction()) {
        case MotionEvent.ACTION_DOWN:
            downY = (int) ev.getY();
            break;
        case MotionEvent.ACTION_MOVE:
            //如果是正在刷新状态滑动没有
            if(currentState==REFING){
                break;
            }
                
            int deltaY = (int) (ev.getY() - downY);// 得到移动的距离
            int currentHeight = -headHeight + deltaY;
            // 判断当前的距离是不是大于headHeight 并且显示的是第一个位置
            if (currentHeight > -headHeight && getFirstVisiblePosition() == 0) {
                v.setPadding(0, currentHeight, 0, 0);// 展现头部
                if (currentHeight >= 0 && currentState == PULL_REF) {
                    currentState = REL_REF;
                    refHeadView();
                } else if (currentHeight < 0 && currentState == REL_REF) {
                    currentState = PULL_REF;
                    refHeadView();
                }
                return true;// 拦截事件不让listview处理
            }
            break;
        case MotionEvent.ACTION_UP:
            //判断当前是不是要刷新状态
            if(currentState==PULL_REF){
                v.setPadding(0, -headHeight, 0, 0);
            }else if(currentState==REL_REF){
                currentState=REFING;
                v.setPadding(0,0, 0, 0);
                refHeadView();
                if(listener!=null){
                    listener.setPullRfe();
                }
            }
            break;
        }
        return super.onTouchEvent(ev);
    }

    private void refHeadView() {
        switch (currentState) {
        case PULL_REF:
            tv.setText("下拉刷新");
            img.startAnimation(downAnimation);
            break;
        case REL_REF:
            tv.setText("松开刷新");
            img.startAnimation(upAnimation);
            break;
        case REFING:
            tv.setText("正在刷新……");
            img.setVisibility(View.GONE);
            img.clearAnimation();
            pb.setVisibility(View.VISIBLE);
            break;

        default:
            break;
        }

    }
    //刷新完成要把控件和状态重置
    public void completeRef(){
        v.setPadding(0, -headHeight, 0, 0);// 展现头部
        currentState=PULL_REF;
        tv.setText("下拉刷新");
        img.setVisibility(View.VISIBLE);
        pb.setVisibility(View.GONE);
        SimpleDateFormat sDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
        String date = sDateFormat.format(new java.util.Date());
        tvtiem.setText("最后刷新:"+date);
        
    }
    private OnRefLisner listener;
    public void setOnRefLisner(OnRefLisner listener){
        this.listener = listener;
    }
    //回调接口
    public interface OnRefLisner{
        void setPullRfe(); 
    }

}

package com.example.listviewf5;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.example.listviewf5.MyListView.OnRefLisner;

import android.os.Bundle;
import android.os.Handler;
import android.app.Activity;
import android.view.Menu;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;

public class MainActivity extends Activity {
    private MyListView lv;
    private List<Map<String, Object>> list;
    private SimpleAdapter sa;
    private Handler handler = new Handler(){
        public void handleMessage(android.os.Message msg) {
            sa.notifyDataSetChanged();
            lv.completeRef();
            
        };
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv = (MyListView) findViewById(R.id.lv);
        list = new ArrayList<Map<String,Object>>();
        for (int i = 0; i <20; i++) {
            Map<String, Object> map = new HashMap<String, Object>();
            map.put("key1","神马都是浮云");
            map.put("key2","heheda");
            list.add(map);
        }
        sa = new SimpleAdapter(this, list,R.layout.item_lv, new String[]{"key1","key2"},new int[]{R.id.tv,R.id.tv2});
        lv.setAdapter(sa);
        lv.setOnRefLisner(new OnRefLisner() {
            
            @Override
            public void setPullRfe() {
                Map<String, Object> map = new HashMap<String, Object>();
                map.put("key1","下拉更新的数据");
                map.put("key2","hehedaheheda");
                list.add(0, map);
                handler.sendEmptyMessageDelayed(0,3000);
            }
        });
    }
}