Android 下拉刷新控件

咱們今天就來實現一個下拉刷新控件。由於有時候不僅僅是ListView需要下拉刷新，ExpandableListView和GridView也有這個需求，由於ListView，GridView都是AbsListView的子類，ExpandableListView是ListView的子類所以也是AbsListView的子類。所以我的思路是自定義一個對所有AbsListView的子類通用的下拉管理布局，叫PullToRefreshLayout，如果需要GridView，只需要在布局文件裡將ListView換成GridView就行了，ExpandableListView也一樣，不需要再繼承什麼GridView啊ListView啊亂七八糟的。

下面講解PullToRefreshLayout的實現，在貼完整的源碼之前先理解整個類的大概思路：

public class PullToRefreshLayout extends RelativeLayout implements OnTouchListener 
{ 

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


  private void hideHead() 
  { 
    // 在這裡開始異步隱藏下拉頭，在松手的時候或這刷新完畢的時候隱藏 
  } 


  public void refreshFinish(int refreshResult) 
  { 
    // 完成刷新操作，顯示刷新結果 
  } 

  private void changeState(int to) 
  { 
    // 改變當前所處的狀態，有四個狀態：下拉刷新、釋放刷新、正在刷新、刷新完成 
  } 

  /* 
   * （非 Javadoc）由父控件決定是否分發事件，防止事件沖突 
   * 
   * @see android.view.ViewGroup#dispatchTouchEvent(android.view.MotionEvent) 
   */ 
  @Override 
  public boolean dispatchTouchEvent(MotionEvent ev) 
  { 
    switch (ev.getActionMasked()) 
    { 
    case MotionEvent.ACTION_DOWN: 
      /*手指按下的時候，無法判斷是否將要下拉，所以這時候break讓父類把down事件分發給子View 
      記錄按下的坐標*/ 
      break; 
    case MotionEvent.ACTION_MOVE: 
      /*如果往上滑動且moveDetaY==0則說明不在下拉，break繼續將move事件分發給子View 
      如果往下拉，則計算下拉的距離moveDeltaY，根據moveDeltaY重新Layout子控件。但是 
      由於down事件傳到了子View，如果不清除子View的事件，會導致子View誤觸發長按事件和點擊事件。所以在這裡清除子View的事件回調。 
      下拉超過一定的距離時，改變當前狀態*/ 
      break; 
    case MotionEvent.ACTION_UP: 
      //根據當前狀態執行刷新操作或者hideHead 
    default: 
      break; 
    } 
    // 事件分發交給父類 
    return super.dispatchTouchEvent(ev); 
  } 



  /* 
   * （非 Javadoc）繪制陰影效果，顏色值可以修改 
   * 
   * @see android.view.ViewGroup#dispatchDraw(android.graphics.Canvas) 
   */
  @Override
  protected void dispatchDraw(Canvas canvas) 
  { 
    //在這裡用一個漸變繪制分界線陰影 
  } 



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


  @Override
  public boolean onTouch(View v, MotionEvent event) 
  { 
    //這個是OnTouchListener的方法，只判斷AbsListView的狀態來決定是否canPull，除此之外不做其他處理 
  } 
} 

可以看到，這裡復寫了ViewGroup的dispatchTouchEvent，這樣就可以掌控事件的分發，如果不了解這個方法可以看一下這篇Android事件分發、View事件Listener全解析。之所以要控制事件分發是因為我們不可能知道手指down在AbsListView上之後將往上滑還是往下拉，所以down事件會分發給AbsListView的，但是在move的時候就需要看情況了，因為我們不想在下拉的同時AbsListView也在滑動，所以在下拉的時候不分發move事件，但這樣問題又來了，前面AbsListView已經接收了down事件，如果這時候不分發move事件給它，它會觸發長按事件或者點擊事件，所以在這裡還需要清除AbsListView消息列表中的callback。
onLayout用於重新布置下拉頭和AbsListView的位置的，這個不難理解。

理解了大概思路之後，看一下PullToRefreshLayout完整的源碼吧~

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; 

/** 
 * 整個下拉刷新就這一個布局，用來管理兩個子控件，其中一個是下拉頭，另一個是包含內容的contentView（可以是AbsListView的任何子類） 
 * 
 * @author 陳靖 
 */
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; 
  // 釋放刷新 
  public static final int RELEASE_TO_REFRESH = 1; 
  // 正在刷新 
  public static final int REFRESHING = 2; 
  // 刷新完畢 
  public static final int DONE = 3; 
  // 當前狀態 
  private int state = PULL_TO_REFRESH; 
  // 刷新回調接口 
  private OnRefreshListener mListener; 
  // 刷新成功 
  public static final int REFRESH_SUCCEED = 0; 
  // 刷新失敗 
  public static final int REFRESH_FAIL = 1; 
  // 下拉頭 
  private View headView; 
  // 內容 
  private View contentView; 
  // 按下Y坐標，上一個事件點Y坐標 
  private float downY, lastY; 
  // 下拉的距離 
  public float moveDeltaY = 0; 
  // 釋放刷新的距離 
  private float refreshDist = 200; 
  private Timer timer; 
  private MyTimerTask mTask; 
  // 回滾速度 
  public float MOVE_SPEED = 8; 
  // 第一次執行布局 
  private boolean isLayout = false; 
  // 是否可以下拉 
  private boolean canPull = true; 
  // 在刷新過程中滑動操作 
  private boolean isTouchInRefreshing = false; 
  // 手指滑動距離與下拉頭的滑動距離比，中間會隨正切函數變化 
  private float radio = 2; 
  // 下拉箭頭的轉180°動畫 
  private RotateAnimation rotateAnimation; 
  // 均勻旋轉動畫 
  private RotateAnimation refreshingAnimation; 
  // 下拉的箭頭 
  private View pullView; 
  // 正在刷新的圖標 
  private View refreshingView; 
  // 刷新結果圖標 
  private View stateImageView; 
  // 刷新結果：成功或失敗 
  private TextView stateTextView; 
  /** 
   * 執行自動回滾的handler 
   */
  Handler updateHandler = new Handler() 
  { 

    @Override
    public void handleMessage(Message msg) 
    { 
      // 回彈速度隨下拉距離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，且沒有往上推的話則懸停，顯示"正在刷新..." 
        moveDeltaY = refreshDist; 
        mTask.cancel(); 
      } 
      if (canPull) 
        moveDeltaY -= MOVE_SPEED; 
      if (moveDeltaY <= 0) 
      { 
        // 已完成回彈 
        moveDeltaY = 0; 
        pullView.clearAnimation(); 
        // 隱藏下拉頭時有可能還在刷新，只有當前狀態不是正在刷新時才改變狀態 
        if (state != REFRESHING) 
          changeState(PULL_TO_REFRESH); 
        mTask.cancel(); 
      } 
      // 刷新布局,會自動調用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); 
    // 添加勻速轉動動畫 
    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，顯示刷新結果 
   */
  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: 
      // 刷新失敗 
      stateImageView.setVisibility(View.VISIBLE); 
      stateTextView.setText(R.string.refresh_fail); 
      stateImageView.setBackgroundResource(R.drawable.refresh_failed); 
      break; 
    default: 
      break; 
    } 
    // 刷新結果停留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: 
      // 釋放刷新 
      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）由父控件決定是否分發事件，防止事件沖突 
   * 
   * @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(); 
      } 
      /* 
       * 觸碰的地方位於下拉頭布局，由於我們沒有對下拉頭做事件響應，這時候它會給咱返回一個false導致接下來的事件不再分發進來。 
       * 所以我們不能交給父類分發，直接返回true 
       */ 
      if (ev.getY() < moveDeltaY) 
        return true; 
      break; 
    case MotionEvent.ACTION_MOVE: 
      // canPull這個值在底下onTouch中會根據ListView是否滑到頂部來改變，意思是是否可下拉 
      if (canPull) 
      { 
        // 對實際滑動距離做縮小，造成用力拉的感覺 
        moveDeltaY = moveDeltaY + (ev.getY() - lastY) / radio; 
        if (moveDeltaY < 0) 
          moveDeltaY = 0; 
        if (moveDeltaY > getMeasuredHeight()) 
          moveDeltaY = getMeasuredHeight(); 
        if (state == REFRESHING) 
        { 
          // 正在刷新的時候觸摸移動 
          isTouchInRefreshing = true; 
        } 
      } 
      lastY = ev.getY(); 
      // 根據下拉距離改變比例 
      radio = (float) (2 + 2 * Math.tan(Math.PI / 2 / getMeasuredHeight() * moveDeltaY)); 
      requestLayout(); 
      if (moveDeltaY <= refreshDist && state == RELEASE_TO_REFRESH) 
      { 
        // 如果下拉距離沒達到刷新的距離且當前狀態是釋放刷新，改變狀態為下拉刷新 
        changeState(PULL_TO_REFRESH); 
      } 
      if (moveDeltaY >= refreshDist && state == PULL_TO_REFRESH) 
      { 
        changeState(RELEASE_TO_REFRESH); 
      } 
      if (moveDeltaY > 8) 
      { 
        // 防止下拉過程中誤觸發長按事件和點擊事件 
        clearContentViewEvents(); 
      } 
      if (moveDeltaY > 0) 
      { 
        // 正在下拉，不讓子控件捕獲事件 
        return true; 
      } 
      break; 
    case MotionEvent.ACTION_UP: 
      if (moveDeltaY > refreshDist) 
        // 正在刷新時往下拉釋放後下拉頭不隱藏 
        isTouchInRefreshing = false; 
      if (state == RELEASE_TO_REFRESH) 
      { 
        changeState(REFRESHING); 
        // 刷新操作 
        if (mListener != null) 
          mListener.onRefresh(); 
      } else 
      { 

      } 
      hideHead(); 
    default: 
      break; 
    } 
    // 事件分發交給父類 
    return super.dispatchTouchEvent(ev); 
  } 

  /** 
   * 通過反射修改字段去掉長按事件和點擊事件 
   */ 
  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，通過反射獲取並從消息列表刪除，去掉長按事件 
          fields[i].setAccessible(true); 
          contentView.getHandler().removeCallbacks((Runnable) fields[i].get(contentView)); 
        } else if (fields[i].getName().equals("mTouchMode")) 
        { 
          // TOUCH_MODE_REST = -1， 這個可以去除點擊事件 
          fields[i].setAccessible(true); 
          fields[i].set(contentView, -1); 
        } 
      // 去掉焦點 
      ((AbsListView) contentView).getSelector().setState(new int[] 
      { 0 }); 
    } catch (Exception e) 
    { 
      Log.d(TAG, "error : " + e.toString()); 
    } 
  } 

  /* 
   * （非 Javadoc）繪制陰影效果，顏色值可以修改 
   * 
   * @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); 
    // 陰影的高度為26 
    LinearGradient linearGradient = new LinearGradient(0, moveDeltaY, 0, moveDeltaY - 26, 0x66000000, 0x00000000, TileMode.CLAMP); 
    paint.setShader(linearGradient); 
    paint.setStyle(Style.FILL); 
    // 在moveDeltaY處往上變淡 
    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) 
    { 
      // 這裡是第一次進來的時候做一些初始化 
      headView = getChildAt(0); 
      contentView = getChildAt(1); 
      // 給AbsListView設置OnTouchListener 
      contentView.setOnTouchListener(this); 
      isLayout = true; 
      initView(); 
      refreshDist = ((ViewGroup) headView).getChildAt(0).getMeasuredHeight(); 
    } 
    if (canPull) 
    { 
      // 改變子控件的布局 
      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) 
  { 
    // 第一個item可見且滑動到頂部 
    AbsListView alv = null; 
    try
    { 
      alv = (AbsListView) v; 
    } catch (Exception e) 
    { 
      Log.d(TAG, e.getMessage()); 
      return false; 
    } 
    if (alv.getCount() == 0) 
    { 
      // 沒有item的時候也可以下拉刷新 
      canPull = true; 
    } else if (alv.getFirstVisiblePosition() == 0 && alv.getChildAt(0).getTop() >= 0) 
    { 
      // 滑到AbsListView的頂部了 
      canPull = true; 
    } else
      canPull = false; 
    return false; 
  } 
} 

代碼中的注釋已經寫的很清楚了。
既然PullToRefreshLayout已經寫好了，接下來就來使用這個Layout實現下拉刷新~

首先得寫個OnRefreshListener接口來回調刷新操作：

public interface OnRefreshListener { 
  void onRefresh(); 
} 

就一個刷新操作的方法，待會兒讓Activity實現這個接口就可以在Activity中執行刷新操作了。

看一下MainActivity的布局：

PullToRefreshLayout只能包含兩個子控件：refresh_head和content_view。
看一下refresh_head的布局：

可以根據需要修改refresh_head的布局然後在PullToRefreshLayout中處理，但是相關View的id要和PullToRefreshLayout中用到的保持同步！

接下來是MainActivity的代碼：

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為ListView的情況下我給ListView增加了FooterView，實現點擊加載更多 
 * 
 * @author 陳靖 
 * 
 */
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); 
    // 添加勻速轉動動畫 
    LinearInterpolator lir = new LinearInterpolator(); 
    loadingAnimation.setInterpolator(lir); 
  } 

  /** 
   * ListView初始化方法 
   */
  private void initListView() 
  { 
    List items = new ArrayList(); 
    for (int i = 0; i < 30; i++) 
    { 
      items.add("這裡是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 items = new ArrayList(); 
    for (int i = 0; i < 30; i++) 
    { 
      items.add("這裡是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)) 
        { 
          // 如果展開則關閉 
          parent.collapseGroup(groupPosition); 
        } else
        { 
          // 如果關閉則打開，注意這裡是手動打開不要默認滾動否則會有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[] { "這裡是group 0", 
                    // "這裡是group 1", "這裡是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("這裡是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("這裡是group " + i + "裡的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中判斷contentView是ListView的話給ListView添加了FooterView實現點擊加載更多的功能。這只是一個演示PullToRefreshLayout使用的demo，可以參照一下修改。我已經在裡面寫了ListView，GridView和ExpandableListView的初始化方法，根據自己使用的是哪個來調用吧。那麼這是ListView的下拉刷新和加載更多。如果我要GridView也有下拉刷新功能呢？那就把MainActivity的布局換成這樣：

怎麼樣？很簡單吧？簡單易用，不用再去繼承修改了。

希望本文所述對大家學習Android下拉刷新控件有所幫助。