Android自定义控件实战——下拉刷新控件终结者：PullT

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：

[java] view plaincopy

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~

[java] view plaincopy

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：

[java] view plaincopy

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：

[html] view plaincopy

<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：

[html] view plaincopy

<?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：

[java] view plaincopy

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：

[html] view plaincopy

<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：

[html] view plaincopy

<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~
点击下载源码