Android自定义控件实战——下拉刷新控件终结者：PullToRefreshLayout

转载请声明出处http://blog.csdn.net/zhongkejingwang/article/details/38340701    

       说到下拉刷新控件，网上版本有很多，很多软件也都有下拉刷新功能。有一个叫XListView的，我看别人用过，没看过是咋实现的，看这名字估计是继承自ListView修改的，不过效果看起来挺丑的，也没什么扩展性，太单调了。看了QQ2014的列表下拉刷新，发现挺好看的，我喜欢，贴一下图看一下qq的下拉刷新效果：

                                          

    不错吧？嗯，是的。一看就知道实现方式不一样。咱们今天就来实现一个下拉刷新控件。由于有时候不仅仅是ListView需要下拉刷新，ExpandableListView和GridView也有这个需求，由于ListView，GridView都是AbsListView的子类，ExpandableListView是ListView的子类所以也是AbsListView的子类。所以我的思路是自定义一个对所有AbsListView的子类通用的下拉管理布局，叫PullToRefreshLayout，如果需要GridView，只需要在布局文件里将ListView换成GridView就行了，ExpandableListView也一样，不需要再继承什么GridView啊ListView啊乱七八糟的。

看上图，主要工作就是定义黑色大布局，红色部分是不下拉的时候的可见部分，可以是任意的AbsListView的子类（GridView，ListView，ExpandableListView等等）。其实我已经写好了，先看一下效果图：

正常拉法：

                          

强迫症拉法：

                 

上面是ListView的，下面是GridView的

                  

再来看一下ExpandableListView的下拉刷新效果：

                              

可以看到，点击事件和长按事件都能正常触发而不会误触发，在使用ExpandableListView的时候需要注意禁止展开时自动滚动，否则会出现bug。后面会提供demo源码下载，可以根据自己的需求去修改。

下面讲解PullToRefreshLayout的实现，在贴完整的源码之前先理解整个类的大概思路：

 public class PullToRefreshLayout extends RelativeLayout implements OnTouchListener
 {

     // 下拉的距离
     public float moveDeltaY = 0;
     // 是否可以下拉
     private boolean canPull = true;


     private void hideHead()
     {
         // 在这里开始异步隐藏下拉头，在松手的时候或这刷新完毕的时候隐藏
     }


     public void refreshFinish(int refreshResult)
     {
         // 完成刷新操作，显示刷新结果
     }

     private void changeState(int to)
     {
         // 改变当前所处的状态，有四个状态：下拉刷新、释放刷新、正在刷新、刷新完成
     }

     /*
      * （非 Javadoc）由父控件决定是否分发事件，防止事件冲突
      *
      * @see android.view.ViewGroup#dispatchTouchEvent(android.view.MotionEvent)
      */
     @Override
     public boolean dispatchTouchEvent(MotionEvent ev)
     {
         switch (ev.getActionMasked())
         {
         case MotionEvent.ACTION_DOWN:
             /*手指按下的时候，无法判断是否将要下拉，所以这时候break让父类把down事件分发给子View
             记录按下的坐标*/
             break;
         case MotionEvent.ACTION_MOVE:
             /*如果往上滑动且moveDetaY==0则说明不在下拉，break继续将move事件分发给子View
             如果往下拉，则计算下拉的距离moveDeltaY，根据moveDeltaY重新Layout子控件。但是
             由于down事件传到了子View，如果不清除子View的事件，会导致子View误触发长按事件和点击事件。所以在这里清除子View的事件回调。
             下拉超过一定的距离时，改变当前状态*/
             break;
         case MotionEvent.ACTION_UP:
             //根据当前状态执行刷新操作或者hideHead
         default:
             break;
         }
         // 事件分发交给父类
         return super.dispatchTouchEvent(ev);
     }



     /*
      * （非 Javadoc）绘制阴影效果，颜色值可以修改
      *
      * @see android.view.ViewGroup#dispatchDraw(android.graphics.Canvas)
      */
     @Override
     protected void dispatchDraw(Canvas canvas)
     {
         //在这里用一个渐变绘制分界线阴影
     }



     @Override
     protected void onLayout(boolean changed, int l, int t, int r, int b)
     {
         //这个方法就是重新Layout子View了，根据moveDeltaY来定位子View的位置
     }


     @Override
     public boolean onTouch(View v, MotionEvent event)
     {
         //这个是OnTouchListener的方法，只判断AbsListView的状态来决定是否canPull，除此之外不做其他处理
     }
 }

可以看到，这里复写了ViewGroup的dispatchTouchEvent，这样就可以掌控事件的分发，如果不了解这个方法可以看一下这篇Android事件分发、View事件Listener全解析。之所以要控制事件分发是因为我们不可能知道手指down在AbsListView上之后将往上滑还是往下拉，所以down事件会分发给AbsListView的，但是在move的时候就需要看情况了，因为我们不想在下拉的同时AbsListView也在滑动，所以在下拉的时候不分发move事件，但这样问题又来了，前面AbsListView已经接收了down事件，如果这时候不分发move事件给它，它会触发长按事件或者点击事件，所以在这里还需要清除AbsListView消息列表中的callback。

onLayout用于重新布置下拉头和AbsListView的位置的，这个不难理解。

理解了大概思路之后，看一下PullToRefreshLayout完整的源码吧~

 package com.jingchen.pulltorefresh;

 import java.lang.reflect.Field;
 import java.util.Timer;
 import java.util.TimerTask;

 import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.LinearGradient;
 import android.graphics.Paint;
 import android.graphics.Paint.Style;
 import android.graphics.RectF;
 import android.graphics.Shader.TileMode;
 import android.os.Handler;
 import android.os.Message;
 import android.util.AttributeSet;
 import android.util.Log;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.View.OnTouchListener;
 import android.view.ViewGroup;
 import android.view.animation.AnimationUtils;
 import android.view.animation.LinearInterpolator;
 import android.view.animation.RotateAnimation;
 import android.widget.AbsListView;
 import android.widget.RelativeLayout;
 import android.widget.TextView;

 /**
  * 整个下拉刷新就这一个布局，用来管理两个子控件，其中一个是下拉头，另一个是包含内容的contentView（可以是AbsListView的任何子类）
  *
  * @author 陈靖
  */
 public class PullToRefreshLayout extends RelativeLayout implements OnTouchListener
 {
     public static final String TAG = "PullToRefreshLayout";
     // 下拉刷新
     public static final int PULL_TO_REFRESH = 0;
     // 释放刷新
     public static final int RELEASE_TO_REFRESH = 1;
     // 正在刷新
     public static final int REFRESHING = 2;
     // 刷新完毕
     public static final int DONE = 3;
     // 当前状态
     private int state = PULL_TO_REFRESH;
     // 刷新回调接口
     private OnRefreshListener mListener;
     // 刷新成功
     public static final int REFRESH_SUCCEED = 0;
     // 刷新失败
     public static final int REFRESH_FAIL = 1;
     // 下拉头
     private View headView;
     // 内容
     private View contentView;
     // 按下Y坐标，上一个事件点Y坐标
     private float downY, lastY;
     // 下拉的距离
     public float moveDeltaY = 0;
     // 释放刷新的距离
     private float refreshDist = 200;
     private Timer timer;
     private MyTimerTask mTask;
     // 回滚速度
     public float MOVE_SPEED = 8;
     // 第一次执行布局
     private boolean isLayout = false;
     // 是否可以下拉
     private boolean canPull = true;
     // 在刷新过程中滑动操作
     private boolean isTouchInRefreshing = false;
     // 手指滑动距离与下拉头的滑动距离比，中间会随正切函数变化
     private float radio = 2;
     // 下拉箭头的转180°动画
     private RotateAnimation rotateAnimation;
     // 均匀旋转动画
     private RotateAnimation refreshingAnimation;
     // 下拉的箭头
     private View pullView;
     // 正在刷新的图标
     private View refreshingView;
     // 刷新结果图标
     private View stateImageView;
     // 刷新结果：成功或失败
     private TextView stateTextView;
     /**
      * 执行自动回滚的handler
      */
     Handler updateHandler = new Handler()
     {

         @Override
         public void handleMessage(Message msg)
         {
             // 回弹速度随下拉距离moveDeltaY增大而增大
             MOVE_SPEED = (float) (8 + 5 * Math.tan(Math.PI / 2 / getMeasuredHeight() * moveDeltaY));
             if (state == REFRESHING && moveDeltaY <= refreshDist && !isTouchInRefreshing)
             {
                 // 正在刷新，且没有往上推的话则悬停，显示"正在刷新..."
                 moveDeltaY = refreshDist;
                 mTask.cancel();
             }
             if (canPull)
                 moveDeltaY -= MOVE_SPEED;
             if (moveDeltaY <= 0)
             {
                 // 已完成回弹
                 moveDeltaY = 0;
                 pullView.clearAnimation();
                 // 隐藏下拉头时有可能还在刷新，只有当前状态不是正在刷新时才改变状态
                 if (state != REFRESHING)
                     changeState(PULL_TO_REFRESH);
                 mTask.cancel();
             }
             // 刷新布局,会自动调用onLayout
             requestLayout();
         }

     };

     public void setOnRefreshListener(OnRefreshListener listener)
     {
         mListener = listener;
     }

     public PullToRefreshLayout(Context context)
     {
         super(context);
         initView(context);
     }

     public PullToRefreshLayout(Context context, AttributeSet attrs)
     {
         super(context, attrs);
         initView(context);
     }

     public PullToRefreshLayout(Context context, AttributeSet attrs, int defStyle)
     {
         super(context, attrs, defStyle);
         initView(context);
     }

     private void initView(Context context)
     {
         timer = new Timer();
         mTask = new MyTimerTask(updateHandler);
         rotateAnimation = (RotateAnimation) AnimationUtils.loadAnimation(context, R.anim.reverse_anim);
         refreshingAnimation = (RotateAnimation) AnimationUtils.loadAnimation(context, R.anim.rotating);
         // 添加匀速转动动画
         LinearInterpolator lir = new LinearInterpolator();
         rotateAnimation.setInterpolator(lir);
         refreshingAnimation.setInterpolator(lir);
     }

     private void hideHead()
     {
         if (mTask != null)
         {
             mTask.cancel();
             mTask = null;
         }
         mTask = new MyTimerTask(updateHandler);
         timer.schedule(mTask, 0, 5);
     }

     /**
      * 完成刷新操作，显示刷新结果
      */
     public void refreshFinish(int refreshResult)
     {
         refreshingView.clearAnimation();
         refreshingView.setVisibility(View.GONE);
         switch (refreshResult)
         {
         case REFRESH_SUCCEED:
             // 刷新成功
             stateImageView.setVisibility(View.VISIBLE);
             stateTextView.setText(R.string.refresh_succeed);
             stateImageView.setBackgroundResource(R.drawable.refresh_succeed);
             break;
         case REFRESH_FAIL:
             // 刷新失败
             stateImageView.setVisibility(View.VISIBLE);
             stateTextView.setText(R.string.refresh_fail);
             stateImageView.setBackgroundResource(R.drawable.refresh_failed);
             break;
         default:
             break;
         }
         // 刷新结果停留1秒
         new Handler()
         {
             @Override
             public void handleMessage(Message msg)
             {
                 state = PULL_TO_REFRESH;
                 hideHead();
             }
         }.sendEmptyMessageDelayed(0, 1000);
     }

     private void changeState(int to)
     {
         state = to;
         switch (state)
         {
         case PULL_TO_REFRESH:
             // 下拉刷新
             stateImageView.setVisibility(View.GONE);
             stateTextView.setText(R.string.pull_to_refresh);
             pullView.clearAnimation();
             pullView.setVisibility(View.VISIBLE);
             break;
         case RELEASE_TO_REFRESH:
             // 释放刷新
             stateTextView.setText(R.string.release_to_refresh);
             pullView.startAnimation(rotateAnimation);
             break;
         case REFRESHING:
             // 正在刷新
             pullView.clearAnimation();
             refreshingView.setVisibility(View.VISIBLE);
             pullView.setVisibility(View.INVISIBLE);
             refreshingView.startAnimation(refreshingAnimation);
             stateTextView.setText(R.string.refreshing);
             break;
         default:
             break;
         }
     }

     /*
      * （非 Javadoc）由父控件决定是否分发事件，防止事件冲突
      *
      * @see android.view.ViewGroup#dispatchTouchEvent(android.view.MotionEvent)
      */
     @Override
     public boolean dispatchTouchEvent(MotionEvent ev)
     {
         switch (ev.getActionMasked())
         {
         case MotionEvent.ACTION_DOWN:
             downY = ev.getY();
             lastY = downY;
             if (mTask != null)
             {
                 mTask.cancel();
             }
             /*
              * 触碰的地方位于下拉头布局，由于我们没有对下拉头做事件响应，这时候它会给咱返回一个false导致接下来的事件不再分发进来。
              * 所以我们不能交给父类分发，直接返回true
              */
             if (ev.getY() < moveDeltaY)
                 return true;
             break;
         case MotionEvent.ACTION_MOVE:
             // canPull这个值在底下onTouch中会根据ListView是否滑到顶部来改变，意思是是否可下拉
             if (canPull)
             {
                 // 对实际滑动距离做缩小，造成用力拉的感觉
                 moveDeltaY = moveDeltaY + (ev.getY() - lastY) / radio;
                 if (moveDeltaY < 0)
                     moveDeltaY = 0;
                 if (moveDeltaY > getMeasuredHeight())
                     moveDeltaY = getMeasuredHeight();
                 if (state == REFRESHING)
                 {
                     // 正在刷新的时候触摸移动
                     isTouchInRefreshing = true;
                 }
             }
             lastY = ev.getY();
             // 根据下拉距离改变比例
             radio = (float) (2 + 2 * Math.tan(Math.PI / 2 / getMeasuredHeight() * moveDeltaY));
             requestLayout();
             if (moveDeltaY <= refreshDist && state == RELEASE_TO_REFRESH)
             {
                 // 如果下拉距离没达到刷新的距离且当前状态是释放刷新，改变状态为下拉刷新
                 changeState(PULL_TO_REFRESH);
             }
             if (moveDeltaY >= refreshDist && state == PULL_TO_REFRESH)
             {
                 changeState(RELEASE_TO_REFRESH);
             }
             if (moveDeltaY > 8)
             {
                 // 防止下拉过程中误触发长按事件和点击事件
                 clearContentViewEvents();
             }
             if (moveDeltaY > 0)
             {
                 // 正在下拉，不让子控件捕获事件
                 return true;
             }
             break;
         case MotionEvent.ACTION_UP:
             if (moveDeltaY > refreshDist)
                 // 正在刷新时往下拉释放后下拉头不隐藏
                 isTouchInRefreshing = false;
             if (state == RELEASE_TO_REFRESH)
             {
                 changeState(REFRESHING);
                 // 刷新操作
                 if (mListener != null)
                     mListener.onRefresh();
             } else
             {

             }
             hideHead();
         default:
             break;
         }
         // 事件分发交给父类
         return super.dispatchTouchEvent(ev);
     }

     /**
      * 通过反射修改字段去掉长按事件和点击事件
      */
     private void clearContentViewEvents()
     {
         try
         {
             Field[] fields = AbsListView.class.getDeclaredFields();
             for (int i = 0; i < fields.length; i++)
                 if (fields[i].getName().equals("mPendingCheckForLongPress"))
                 {
                     // mPendingCheckForLongPress是AbsListView中的字段，通过反射获取并从消息列表删除，去掉长按事件
                     fields[i].setAccessible(true);
                     contentView.getHandler().removeCallbacks((Runnable) fields[i].get(contentView));
                 } else if (fields[i].getName().equals("mTouchMode"))
                 {
                     // TOUCH_MODE_REST = -1， 这个可以去除点击事件
                     fields[i].setAccessible(true);
                     fields[i].set(contentView, -1);
                 }
             // 去掉焦点
             ((AbsListView) contentView).getSelector().setState(new int[]
             { 0 });
         } catch (Exception e)
         {
             Log.d(TAG, "error : " + e.toString());
         }
     }

     /*
      * （非 Javadoc）绘制阴影效果，颜色值可以修改
      *
      * @see android.view.ViewGroup#dispatchDraw(android.graphics.Canvas)
      */
     @Override
     protected void dispatchDraw(Canvas canvas)
     {
         super.dispatchDraw(canvas);
         if (moveDeltaY == 0)
             return;
         RectF rectF = new RectF(0, 0, getMeasuredWidth(), moveDeltaY);
         Paint paint = new Paint();
         paint.setAntiAlias(true);
         // 阴影的高度为26
         LinearGradient linearGradient = new LinearGradient(0, moveDeltaY, 0, moveDeltaY - 26, 0x66000000, 0x00000000, TileMode.CLAMP);
         paint.setShader(linearGradient);
         paint.setStyle(Style.FILL);
         // 在moveDeltaY处往上变淡
         canvas.drawRect(rectF, paint);
     }

     private void initView()
     {
         pullView = headView.findViewById(R.id.pull_icon);
         stateTextView = (TextView) headView.findViewById(R.id.state_tv);
         refreshingView = headView.findViewById(R.id.refreshing_icon);
         stateImageView = headView.findViewById(R.id.state_iv);
     }

     @Override
     protected void onLayout(boolean changed, int l, int t, int r, int b)
     {
         if (!isLayout)
         {
             // 这里是第一次进来的时候做一些初始化
             headView = getChildAt(0);
             contentView = getChildAt(1);
             // 给AbsListView设置OnTouchListener
             contentView.setOnTouchListener(this);
             isLayout = true;
             initView();
             refreshDist = ((ViewGroup) headView).getChildAt(0).getMeasuredHeight();
         }
         if (canPull)
         {
             // 改变子控件的布局
             headView.layout(0, (int) moveDeltaY - headView.getMeasuredHeight(), headView.getMeasuredWidth(), (int) moveDeltaY);
             contentView.layout(0, (int) moveDeltaY, contentView.getMeasuredWidth(), (int) moveDeltaY + contentView.getMeasuredHeight());
         }else super.onLayout(changed, l, t, r, b);
     }

     class MyTimerTask extends TimerTask
     {
         Handler handler;

         public MyTimerTask(Handler handler)
         {
             this.handler = handler;
         }

         @Override
         public void run()
         {
             handler.sendMessage(handler.obtainMessage());
         }

     }

     @Override
     public boolean onTouch(View v, MotionEvent event)
     {
         // 第一个item可见且滑动到顶部
         AbsListView alv = null;
         try
         {
             alv = (AbsListView) v;
         } catch (Exception e)
         {
             Log.d(TAG, e.getMessage());
             return false;
         }
         if (alv.getCount() == 0)
         {
             // 没有item的时候也可以下拉刷新
             canPull = true;
         } else if (alv.getFirstVisiblePosition() == 0 && alv.getChildAt(0).getTop() >= 0)
         {
             // 滑到AbsListView的顶部了
             canPull = true;
         } else
             canPull = false;
         return false;
     }
 }

代码中的注释已经写的很清楚了。

既然PullToRefreshLayout已经写好了，接下来就来使用这个Layout实现下拉刷新~

首先得写个OnRefreshListener接口来回调刷新操作：

 public interface OnRefreshListener {
     void onRefresh();
 }

就一个刷新操作的方法，待会儿让Activity实现这个接口就可以在Activity中执行刷新操作了。

看一下MainActivity的布局：

 <com.jingchen.pulltorefresh.PullToRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/refresh_view"
     android:layout_width="match_parent"
     android:layout_height="match_parent" >

     <include layout="@layout/refresh_head" />

     <!-- 支持AbsListView的所有子类 -->
     <ListView
         android:id="@+id/content_view"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:background="@color/white"
         android:divider="@color/gray"
         android:dividerHeight="1dp" >
     </ListView>

 </com.jingchen.pulltorefresh.PullToRefreshLayout>

PullToRefreshLayout只能包含两个子控件：refresh_head和content_view。

看一下refresh_head的布局：

 <?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/head_view"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:background="@color/light_blue" >

     <RelativeLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_alignParentBottom="true"
         android:paddingBottom="20dp"
         android:paddingTop="20dp" >

         <RelativeLayout
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:layout_centerInParent="true" >

             <ImageView
                 android:id="@+id/pull_icon"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_centerVertical="true"
                 android:layout_marginLeft="60dp"
                 android:background="@drawable/pull_icon_big" />

             <ImageView
                 android:id="@+id/refreshing_icon"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_centerVertical="true"
                 android:layout_marginLeft="60dp"
                 android:background="@drawable/refreshing"
                 android:visibility="gone" />

             <TextView
                 android:id="@+id/state_tv"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_centerInParent="true"
                 android:text="@string/pull_to_refresh"
                 android:textColor="@color/white"
                 android:textSize="16sp" />

             <ImageView
                 android:id="@+id/state_iv"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_centerVertical="true"
                 android:layout_marginRight="8dp"
                 android:layout_toLeftOf="@id/state_tv"
                 android:visibility="gone" />
         </RelativeLayout>
     </RelativeLayout>

 </RelativeLayout>

可以根据需要修改refresh_head的布局然后在PullToRefreshLayout中处理，但是相关View的id要和PullToRefreshLayout中用到的保持同步！

接下来是MainActivity的代码：

 package com.jingchen.pulltorefresh;

 import java.util.ArrayList;
 import java.util.List;

 import android.app.Activity;
 import android.content.Context;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
 import android.support.v4.view.PagerAdapter;
 import android.support.v4.view.ViewPager;
 import android.support.v4.view.ViewPager.OnPageChangeListener;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.view.ViewGroup;
 import android.view.animation.AnimationUtils;
 import android.view.animation.LinearInterpolator;
 import android.view.animation.RotateAnimation;
 import android.widget.AbsListView;
 import android.widget.AdapterView;
 import android.widget.AdapterView.OnItemClickListener;
 import android.widget.AdapterView.OnItemLongClickListener;
 import android.widget.BaseExpandableListAdapter;
 import android.widget.ExpandableListView;
 import android.widget.ExpandableListView.OnChildClickListener;
 import android.widget.ExpandableListView.OnGroupClickListener;
 import android.widget.ListView;
 import android.widget.TextView;
 import android.widget.Toast;

 /**
  * 除了下拉刷新，在contenview为ListView的情况下我给ListView增加了FooterView，实现点击加载更多
  *
  * @author 陈靖
  *
  */
 public class MainActivity extends Activity implements OnRefreshListener, OnClickListener
 {
     private AbsListView alv;
     private PullToRefreshLayout refreshLayout;
     private View loading;
     private RotateAnimation loadingAnimation;
     private TextView loadTextView;
     private MyAdapter adapter;
     private boolean isLoading = false;

     @Override
     protected void onCreate(Bundle savedInstanceState)
     {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         init();
     }

     private void init()
     {
         alv = (AbsListView) findViewById(R.id.content_view);
         refreshLayout = (PullToRefreshLayout) findViewById(R.id.refresh_view);
         refreshLayout.setOnRefreshListener(this);
         initListView();

         loadingAnimation = (RotateAnimation) AnimationUtils.loadAnimation(this, R.anim.rotating);
         // 添加匀速转动动画
         LinearInterpolator lir = new LinearInterpolator();
         loadingAnimation.setInterpolator(lir);
     }

     /**
      * ListView初始化方法
      */
     private void initListView()
     {
         List<String> items = new ArrayList<String>();
         for (int i = 0; i < 30; i++)
         {
             items.add("这里是item " + i);
         }
         // 添加head
         View headView = getLayoutInflater().inflate(R.layout.listview_head, null);
         ((ListView) alv).addHeaderView(headView, null, false);
         // 添加footer
         View footerView = getLayoutInflater().inflate(R.layout.load_more, null);
         loading = footerView.findViewById(R.id.loading_icon);
         loadTextView = (TextView) footerView.findViewById(R.id.loadmore_tv);
         ((ListView) alv).addFooterView(footerView, null, false);
         footerView.setOnClickListener(this);
         adapter = new MyAdapter(this, items);
         alv.setAdapter(adapter);
         alv.setOnItemLongClickListener(new OnItemLongClickListener()
         {

             @Override
             public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id)
             {
                 Toast.makeText(MainActivity.this, "LongClick on " + parent.getAdapter().getItemId(position), Toast.LENGTH_SHORT).show();
                 return true;
             }
         });
         alv.setOnItemClickListener(new OnItemClickListener()
         {

             @Override
             public void onItemClick(AdapterView<?> parent, View view, int position, long id)
             {
                 Toast.makeText(MainActivity.this, " Click on " + parent.getAdapter().getItemId(position), Toast.LENGTH_SHORT).show();
             }
         });
     }

     /**
      * GridView初始化方法
      */
     private void initGridView()
     {
         List<String> items = new ArrayList<String>();
         for (int i = 0; i < 30; i++)
         {
             items.add("这里是item " + i);
         }
         adapter = new MyAdapter(this, items);
         alv.setAdapter(adapter);
         alv.setOnItemLongClickListener(new OnItemLongClickListener()
         {

             @Override
             public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id)
             {
                 Toast.makeText(MainActivity.this, "LongClick on " + parent.getAdapter().getItemId(position), Toast.LENGTH_SHORT).show();
                 return true;
             }
         });
         alv.setOnItemClickListener(new OnItemClickListener()
         {

             @Override
             public void onItemClick(AdapterView<?> parent, View view, int position, long id)
             {
                 Toast.makeText(MainActivity.this, " Click on " + parent.getAdapter().getItemId(position), Toast.LENGTH_SHORT).show();
             }
         });
     }

     /**
      * ExpandableListView初始化方法
      */
     private void initExpandableListView()
     {
         ((ExpandableListView) alv).setAdapter(new ExpandableListAdapter(this));
         ((ExpandableListView) alv).setOnChildClickListener(new OnChildClickListener()
         {

             @Override
             public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id)
             {
                 Toast.makeText(MainActivity.this, " Click on group " + groupPosition + " item " + childPosition, Toast.LENGTH_SHORT).show();
                 return true;
             }
         });
         ((ExpandableListView) alv).setOnItemLongClickListener(new OnItemLongClickListener()
         {

             @Override
             public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id)
             {
                 Toast.makeText(MainActivity.this, "LongClick on " + parent.getAdapter().getItemId(position), Toast.LENGTH_SHORT).show();
                 return true;
             }
         });
         ((ExpandableListView) alv).setOnGroupClickListener(new OnGroupClickListener()
         {

             @Override
             public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id)
             {
                 if (parent.isGroupExpanded(groupPosition))
                 {
                     // 如果展开则关闭
                     parent.collapseGroup(groupPosition);
                 } else
                 {
                     // 如果关闭则打开，注意这里是手动打开不要默认滚动否则会有bug
                     parent.expandGroup(groupPosition);
                 }
                 return true;
             }
         });
     }

     @Override
     public void onRefresh()
     {
         // 下拉刷新操作
         new Handler()
         {
             @Override
             public void handleMessage(Message msg)
             {
                 refreshLayout.refreshFinish(PullToRefreshLayout.REFRESH_SUCCEED);
             }
         }.sendEmptyMessageDelayed(0, 5000);
     }

     @Override
     public void onClick(View v)
     {
         switch (v.getId())
         {
         case R.id.loadmore_layout:
             if (!isLoading)
             {
                 loading.setVisibility(View.VISIBLE);
                 loading.startAnimation(loadingAnimation);
                 loadTextView.setText(R.string.loading);
                 isLoading = true;
             }
             break;
         default:
             break;
         }

     }

     class ExpandableListAdapter extends BaseExpandableListAdapter
     {
         private String[] groupsStrings;// = new String[] { "这里是group 0",
                                         // "这里是group 1", "这里是group 2" };
         private String[][] groupItems;
         private Context context;

         public ExpandableListAdapter(Context context)
         {
             this.context = context;
             groupsStrings = new String[8];
             for (int i = 0; i < groupsStrings.length; i++)
             {
                 groupsStrings[i] = new String("这里是group " + i);
             }
             groupItems = new String[8][8];
             for (int i = 0; i < groupItems.length; i++)
                 for (int j = 0; j < groupItems[i].length; j++)
                 {
                     groupItems[i][j] = new String("这里是group " + i + "里的item " + j);
                 }
         }

         @Override
         public int getGroupCount()
         {
             return groupsStrings.length;
         }

         @Override
         public int getChildrenCount(int groupPosition)
         {
             return groupItems[groupPosition].length;
         }

         @Override
         public Object getGroup(int groupPosition)
         {
             return groupsStrings[groupPosition];
         }

         @Override
         public Object getChild(int groupPosition, int childPosition)
         {
             return groupItems[groupPosition][childPosition];
         }

         @Override
         public long getGroupId(int groupPosition)
         {
             return groupPosition;
         }

         @Override
         public long getChildId(int groupPosition, int childPosition)
         {
             return childPosition;
         }

         @Override
         public boolean hasStableIds()
         {
             return true;
         }

         @Override
         public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent)
         {
             View view = LayoutInflater.from(context).inflate(R.layout.list_item_layout, null);
             TextView tv = (TextView) view.findViewById(R.id.name_tv);
             tv.setText(groupsStrings[groupPosition]);
             return view;
         }

         @Override
         public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent)
         {
             View view = LayoutInflater.from(context).inflate(R.layout.list_item_layout, null);
             TextView tv = (TextView) view.findViewById(R.id.name_tv);
             tv.setText(groupItems[groupPosition][childPosition]);
             return view;
         }

         @Override
         public boolean isChildSelectable(int groupPosition, int childPosition)
         {
             return true;
         }

     }

 }

在MainActivity中判断contentView是ListView的话给ListView添加了FooterView实现点击加载更多的功能。这只是一个演示PullToRefreshLayout使用的demo，可以参照一下修改。我已经在里面写了ListView，GridView和ExpandableListView的初始化方法，根据自己使用的是哪个来调用吧。那么这是ListView的下拉刷新和加载更多。如果我要GridView也有下拉刷新功能呢？那就把MainActivity的布局换成这样：

 <com.jingchen.pulltorefresh.PullToRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/refresh_view"
     android:layout_width="match_parent"
     android:layout_height="match_parent" >

     <include layout="@layout/refresh_head" />
     <!-- 支持AbsListView的所有子类 -->
     <GridView
         android:id="@+id/content_view"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:background="@color/white"
         android:columnWidth="90dp"
         android:gravity="center"
         android:horizontalSpacing="10dp"
         android:numColumns="auto_fit"
         android:stretchMode="columnWidth"
         android:verticalSpacing="15dp" >
     </GridView>

 </com.jingchen.pulltorefresh.PullToRefreshLayout>

如果是ExpandableListView则把布局改成这样：

 <com.jingchen.pulltorefresh.PullToRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/refresh_view"
     android:layout_width="match_parent"
     android:layout_height="match_parent" >

     <include layout="@layout/refresh_head" />
     <!-- 支持AbsListView的所有子类 -->
     <ExpandableListView
         android:id="@+id/content_view"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:background="@color/white" >
     </ExpandableListView>

 </com.jingchen.pulltorefresh.PullToRefreshLayout>

怎么样？很简单吧？简单易用，不用再去继承修改了~

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