自定义ExpandableListView下拉刷新功能简单实现（这里主要说自定义可下拉的功能）
????? ExpandableListView 笔记 ExpandableListVivew 是 ListView 的子类，它在普通 ListView 的基础上进行了扩展， 它把应用中的列表项分为几组，每组里又可包含多个列表项。 ExpandableListVivew 的用法 与普通 ListView 的用法非常相似，只是 ExpandableListVivew 显示的列表项应该由 ExpandableAdapter 提供。
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自定义的类如下：
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package com.xing.wifichat.view;
import android.R.integer;
import android.content.Context;
import android.content.DialogInterface;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.LinearInterpolator;
import android.view.animation.RotateAnimation;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ExpandableListView;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListAdapter;
import android.widget.ProgressBar;
import android.widget.TextView;
import com.xing.wifichat.R;
public class MainExpandableListView extends ExpandableListView implements
??? ??? OnScrollListener {
??? @Override
??? public void setAdapter(ListAdapter adapter) {
??? ??? // TODO Auto-generated method stub
??? ??? super.setAdapter(adapter);
??? }
??? //松开刷新
??? private final static int RELEASE_TO_REFRESH=0;//
??? private final static int PULL_TO_REFRESH=1;//下拉刷新
???
??? private final static int REFRESHING =2;//正在刷新
???
??? private final static int DONE = 3;???
??? private final static int RATIO=3;//实际的padding的距离与界面 上偏移距离 的比例
??? private LayoutInflater inflater;
??? private LinearLayout headLayout;//头linearlayout
??? private TextView tipsTextview;
??? private TextView lastUpdatedTextView;
??? private ImageView arrowImageView;//箭头的图标
???
??? private ProgressBar progressBar;
??? private RotateAnimation animation;
??? // 反转动画
??? private RotateAnimation reverseAnimation;
??? private int headContentWidth;//头部的宽度
???
??? private LinearLayout headView;
??? private int headContentHeight;
????
??? /** 手势按下的起点位置 */
??? private int startY;
??? private int firstItemIndex;
??? private int state;
??? private boolean isBack;
??? //private OnRefreshListener refreshListener;
??? private boolean isRefreshable;
??? public MainExpandableListView(Context context) {
??? ??? super(context);
??? ??? // TODO Auto-generated constructor stub
??? ??? init(context);
??? }
??? public MainExpandableListView(Context context, AttributeSet attrs) {
??? ??? super(context, attrs);
??? ??? // TODO Auto-generated constructor stub
??? ??? init(context);
??? }
??? public void onClick(DialogInterface dialog, int which) {
??? ??? // TODO Auto-generated method stub
??? }
??? public void init(Context context)
??? {
??? ??? inflater =LayoutInflater.from(context);
??? ??? headView =(LinearLayout) inflater.inflate(R.layout.refresh_head, null);
??? ??? arrowImageView = (ImageView) headView.findViewById(R.id.head_arrowImageView);//箭头
??? ??? arrowImageView.setMinimumWidth(70);
??? ??? arrowImageView.setMinimumHeight(50);
??? ??? progressBar = (ProgressBar) headView.findViewById(R.id.head_progressBar);
??? ??? tipsTextview = (TextView) headView.findViewById(R.id.head_tipsTextView);
??? ??? lastUpdatedTextView = (TextView) headView.findViewById(R.id.head_lastUpdatedTextView);
??? ???
??? ??? headView.measure(0, 0);
??? ??? headContentHeight=headView.getMeasuredHeight();
??? ??? headContentWidth=headView.getMeasuredWidth();
??? ???
??? ??? headView.setPadding(0, -headContentHeight, 0, 0);//把headview隐藏到顶部
??? ??? headView.invalidate();//刷新界面
??? ???
??? ??? addHeaderView(headView,null,false);
??? ??? setOnScrollListener(this);//滚动监听
??? ??? animation = new RotateAnimation(0, -180, RotateAnimation.RELATIVE_TO_SELF, 0.5f, RotateAnimation.RELATIVE_TO_SELF, 0.5f);
??? ??? animation.setInterpolator(new LinearInterpolator());
??? ??? animation.setDuration(250);
??? ??? animation.setFillAfter(true);
??? ???
??? ??? reverseAnimation = new RotateAnimation(-180, 0, RotateAnimation.RELATIVE_TO_SELF, 0.5f, RotateAnimation.RELATIVE_TO_SELF, 0.5f);
??? ??? reverseAnimation.setInterpolator(new LinearInterpolator());
??? ??? reverseAnimation.setDuration(200);
??? ??? reverseAnimation.setFillAfter(true);
??? ???
??? ??? state = DONE;
??? ??? isRefreshable = false;
??? }
??? public void onScroll(AbsListView view, int firstVisibleItem,
??? ??? ??? int visibleItemCount, int totalItemCount) {
??? ??? // TODO Auto-generated method stub
??? ??? firstVisibleItem=firstVisibleItem;
??? ???
??? }
??? public void onScrollStateChanged(AbsListView view, int scrollState) {
??? ??? // TODO Auto-generated method stub
??? ???
??? }
??? /**
??? ?* 设置触摸事件 总的思路就是
??? ?*
??? ?* 1 ACTION_DOWN：记录起始位置
??? ?*
??? ?* 2 ACTION_MOVE：计算当前位置与起始位置的距离，来设置state的状态
??? ?*
??? ?* 3 ACTION_UP：根据state的状态来判断是否下载
??? ?*/
??? public boolean onTouchEvent(MotionEvent event)
??? {
??? ??? isRefreshable = true;
??? ??? if (isRefreshable) {
??? ??? ??? switch (event.getAction()) {
??? ??? ??? case MotionEvent.ACTION_DOWN://按下屏幕
??? ??? ??? ??? System.out.println("按下屏");
??? ??? ??? ??? if (firstItemIndex==0) {
??? ??? ??? ??? ??? startY=(int)event.getY();
??? ??? ??? ??? ??? System.out.println("记录down下当前的位置");
??? ??? ??? ??? ???
??? ??? ??? ??? ???
??? ??? ??? ??? }
??? ??? ??? ??? break;
??? ??? ??? ???
??? ??? ??? case MotionEvent.ACTION_MOVE: //移动屏幕
??? ??? ??? ??? System.out.println("移动下屏");
??? ??? ??? ??? int tempY=(int)event.getY();
??? ??? ??? ??? if (state ==PULL_TO_REFRESH) {
??? ??? ??? ??? ??? setSelection(0);//很重要
??? ??? ??? ??? ??? //下拉到可以release_to_refresh的状态
??? ??? ??? ??? ??? if ((tempY-startY)/RATIO>=headContentHeight) {
??? ??? ??? ??? ??? ??? state=RELEASE_TO_REFRESH;
??? ??? ??? ??? ??? ??? isBack=true;
??? ??? ??? ??? ??? ??? changeHeaderViewByState();???
??? ??? ??? ??? ??? }
??? ??? ??? ??? ??? //上推到顶了
??? ??? ??? ??? ??? else if(tempY-startY<=0){
??? ??? ??? ??? ??? ??? state =DONE;
??? ??? ??? ??? ??? ??? changeHeaderViewByState();
??? ??? ??? ??? ??? }
??? ??? ??? ??? ??? headView.setPadding(0, -headContentHeight + (tempY - startY) / RATIO, 0, 0);
??? ??? ??? ??? }
??? ??? ??? ??? if (state == RELEASE_TO_REFRESH) {
??? ??? ??? ??? ??? setSelection(0);
??? ??? ??? ??? ??? // 往上推了，推到了屏幕足够掩盖head的程度，但是还没有推到全部掩盖的地步
??? ??? ??? ??? ??? if (((tempY - startY) / RATIO < headContentHeight) && (tempY - startY) > 0) {
??? ??? ??? ??? ??? ??? state = PULL_TO_REFRESH;
??? ??? ??? ??? ??? ??? changeHeaderViewByState();
//??? ??? ??? ??? ??? ??? Log.v(TAG, "由松开刷新状态转变到下拉刷新状态");
??? ??? ??? ??? ??? }
??? ??? ??? ??? ??? headView.setPadding(0, -headContentHeight + (tempY - startY) / RATIO, 0, 0);
??? ??? ??? ??? }
??? ??? ??? ??? // done状态下
??? ??? ??? ??? if (state == DONE) {
??? ??? ??? ??? ??? if (tempY - startY > 0) {
??? ??? ??? ??? ??? ??? state = PULL_TO_REFRESH;
??? ??? ??? ??? ??? ??? changeHeaderViewByState();
??? ??? ??? ??? ??? }
??? ??? ??? ??? }
??? ??? ??? ??? break;
??? ??? ??? case MotionEvent.ACTION_UP:
??? ??? ??? ??? System.out.println("ACTION_UP");
??? ??? ??? ??? if (state != REFRESHING) {
??? ??? ??? ??? ??? // 不在刷新状态
??? ??? ??? ??? ??? if (state == PULL_TO_REFRESH) {
??? ??? ??? ??? ??? ??? state = DONE;
??? ??? ??? ??? ??? ??? changeHeaderViewByState();
//??? ??? ??? ??? ??? ??? Log.v(TAG, "下拉刷新状态，到done状态");
??? ??? ??? ??? ??? }
??? ??? ??? ??? ??? if (state == RELEASE_TO_REFRESH) {
??? ??? ??? ??? ??? ??? state = REFRESHING;
??? ??? ??? ??? ??? ??? changeHeaderViewByState();
??? ??? ??? ??? ??? ??? isRefreshable = true;
//??? ??? ??? ??? ??? ??? Log.v(TAG, "松开刷新状态，到done状态");
??? ??? ??? ??? ??? }
??? ??? ??? ??? }
??? ??? ??? ??? isBack = false;
??? ??? ??? ??? break;
??? ??? ??? }
??? ??? }
??? ??? return super.onTouchEvent(event);
??? ???
??? }
??? //当状态改变时候，调用 该方法，以更新界面
??? private void changeHeaderViewByState()
??? {
??? ??? switch (state) {
??? ??? case RELEASE_TO_REFRESH:
??? ??? ??? arrowImageView.setVisibility(View.VISIBLE);
??? ??? ??? progressBar.setVisibility(View.GONE);
??? ??? ??? tipsTextview.setVisibility(View.VISIBLE);
??? ??? ??? arrowImageView.clearAnimation();
??? ??? ??? arrowImageView.startAnimation(animation);
??? ??? ??? tipsTextview.setText("松开刷新");
//??? ??? ??? Log.v(TAG, "当前状态，松开刷新");
??? ??? ??? break;
??? ??? case PULL_TO_REFRESH:
??? ??? ??? progressBar.setVisibility(View.GONE);
??? ??? ??? tipsTextview.setVisibility(View.VISIBLE);
??? ??? ??? arrowImageView.clearAnimation();
??? ??? ??? arrowImageView.setVisibility(View.VISIBLE);
??? ??? ??? tipsTextview.setText("下拉刷新");
??? ??? ??? // 是RELEASE_To_REFRESH状态转变来的
??? ??? ??? if (isBack) {
??? ??? ??? ??? isBack = false;
??? ??? ??? ??? arrowImageView.startAnimation(reverseAnimation);
??? ??? ??? }
//??? ??? ??? Log.v(TAG, "当前状态，下拉刷新");
??? ??? ??? break;
??? ??? case REFRESHING:
??? ??? ??? headView.setPadding(0, 0, 0, 0);
??? ??? ??? progressBar.setVisibility(View.VISIBLE);
??? ??? ??? arrowImageView.clearAnimation();
??? ??? ??? arrowImageView.setVisibility(View.GONE);
??? ??? ??? tipsTextview.setText("正在刷新...");
??? ??? ??? break;
??? ??? case DONE:
??? ??? ??? headView.setPadding(0, -headContentHeight, 0, 0);
??? ??? ??? progressBar.setVisibility(View.GONE);
??? ??? ??? arrowImageView.clearAnimation();
??? ??? ??? arrowImageView.setImageResource(R.drawable.arrow);
??? ??? ??? tipsTextview.setText("下拉刷新");
??? ??? ??? break;
??? ??? }
??? }
}
源码可以运行！！！！！！！！！！！！！！！！！
