Android App中ListView仿QQ實現滑動刪除效果的要點解析

本來准備在ListView的每個Item的布局上設置一個隱藏的Button，當滑動的時候顯示。但是因為每次只要存在一個Button，發現每個Item上的Button相互間不好控制。所以決定繼承ListView然後結合PopupWindow。
首先是布局文件：
delete_btn.xml：這裡只需要一個Button

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
  android:orientation="vertical" > 
   <Button  
    android:id="@+id/id_item_btn" 
    android:layout_width="60dp" 
    android:singleLine="true" 
    android:layout_height="wrap_content" 
    android:text="刪除" 
    android:background="@drawable/d_delete_btn" 
    android:textColor="#ffffff" 
    android:paddingLeft="15dp" 
    android:paddingRight="15dp" 
    android:layout_alignParentRight="true" 
    android:layout_centerVertical="true" 
    android:layout_marginRight="15dp" 
    /> 
</LinearLayout> 

主布局文件：activity_main.xml，ListView的每個Item的樣式直接使用了系統的android.R.layout.simple_list_item_1

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
  xmlns:tools="http://schemas.android.com/tools" 
  android:layout_width="match_parent" 
  android:layout_height="match_parent" > 
 
  <com.example.listviewitemslidedeletebtnshow.QQListView 
    android:id="@+id/id_listview" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" > 
  </com.example.listviewitemslidedeletebtnshow.QQListView> 
 
</RelativeLayout> 

接下來看看QQListView的實現：

package com.example.listviewitemslidedeletebtnshow; 
 
import android.content.Context; 
import android.util.AttributeSet; 
import android.view.Gravity; 
import android.view.LayoutInflater; 
import android.view.MotionEvent; 
import android.view.View; 
import android.view.ViewConfiguration; 
import android.widget.Button; 
import android.widget.LinearLayout; 
import android.widget.ListView; 
import android.widget.PopupWindow; 
 
public class QQListView extends ListView 
{ 
 
  private static final String TAG = "QQlistView"; 
 
  // private static final int VELOCITY_SANP = 200; 
  // private VelocityTracker mVelocityTracker; 
  /** 
   * 用戶滑動的最小距離 
   */ 
  private int touchSlop; 
 
  /** 
   * 是否響應滑動 
   */ 
  private boolean isSliding; 
 
  /** 
   * 手指按下時的x坐標 
   */ 
  private int xDown; 
  /** 
   * 手指按下時的y坐標 
   */ 
  private int yDown; 
  /** 
   * 手指移動時的x坐標 
   */ 
  private int xMove; 
  /** 
   * 手指移動時的y坐標 
   */ 
  private int yMove; 
 
  private LayoutInflater mInflater; 
 
  private PopupWindow mPopupWindow; 
  private int mPopupWindowHeight; 
  private int mPopupWindowWidth; 
 
  private Button mDelBtn; 
  /** 
   * 為刪除按鈕提供一個回調接口 
   */ 
  private DelButtonClickListener mListener; 
 
  /** 
   * 當前手指觸摸的View 
   */ 
  private View mCurrentView; 
 
  /** 
   * 當前手指觸摸的位置 
   */ 
  private int mCurrentViewPos; 
 
  /** 
   * 必要的一些初始化 
   * 
   * @param context 
   * @param attrs 
   */ 
  public QQListView(Context context, AttributeSet attrs) 
  { 
    super(context, attrs); 
 
    mInflater = LayoutInflater.from(context); 
    touchSlop = ViewConfiguration.get(context).getScaledTouchSlop(); 
 
    View view = mInflater.inflate(R.layout.delete_btn, null); 
    mDelBtn = (Button) view.findViewById(R.id.id_item_btn); 
    mPopupWindow = new PopupWindow(view, LinearLayout.LayoutParams.WRAP_CONTENT, 
        LinearLayout.LayoutParams.WRAP_CONTENT); 
    /** 
     * 先調用下measure,否則拿不到寬和高 
     */ 
    mPopupWindow.getContentView().measure(0, 0); 
    mPopupWindowHeight = mPopupWindow.getContentView().getMeasuredHeight(); 
    mPopupWindowWidth = mPopupWindow.getContentView().getMeasuredWidth(); 
  } 
 
  @Override 
  public boolean dispatchTouchEvent(MotionEvent ev) 
  { 
    int action = ev.getAction(); 
    int x = (int) ev.getX(); 
    int y = (int) ev.getY(); 
    switch (action) 
    { 
 
    case MotionEvent.ACTION_DOWN: 
      xDown = x; 
      yDown = y; 
      /** 
       * 如果當前popupWindow顯示，則直接隱藏，然後屏蔽ListView的touch事件的下傳 
       */ 
      if (mPopupWindow.isShowing()) 
      { 
        dismissPopWindow(); 
        return false; 
      } 
      // 獲得當前手指按下時的item的位置 
      mCurrentViewPos = pointToPosition(xDown, yDown); 
      // 獲得當前手指按下時的item 
      View view = getChildAt(mCurrentViewPos - getFirstVisiblePosition()); 
      mCurrentView = view; 
      break; 
    case MotionEvent.ACTION_MOVE: 
      xMove = x; 
      yMove = y; 
      int dx = xMove - xDown; 
      int dy = yMove - yDown; 
      /** 
       * 判斷是否是從右到左的滑動 
       */ 
      if (xMove < xDown && Math.abs(dx) > touchSlop && Math.abs(dy) < touchSlop) 
      { 
        // Log.e(TAG, "touchslop = " + touchSlop + " , dx = " + dx + 
        // " , dy = " + dy); 
        isSliding = true; 
      } 
      break; 
    } 
    return super.dispatchTouchEvent(ev); 
  } 
 
  @Override 
  public boolean onTouchEvent(MotionEvent ev) 
  { 
    int action = ev.getAction(); 
    /** 
     * 如果是從右到左的滑動才相應 
     */ 
    if (isSliding) 
    { 
      switch (action) 
      { 
      case MotionEvent.ACTION_MOVE: 
 
        int[] location = new int[2]; 
        // 獲得當前item的位置x與y 
        mCurrentView.getLocationOnScreen(location); 
        // 設置popupWindow的動畫 
        mPopupWindow.setAnimationStyle(R.style.popwindow_delete_btn_anim_style); 
        mPopupWindow.update(); 
        mPopupWindow.showAtLocation(mCurrentView, Gravity.LEFT | Gravity.TOP, 
            location[0] + mCurrentView.getWidth(), location[1] + mCurrentView.getHeight() / 2 
                - mPopupWindowHeight / 2); 
        // 設置刪除按鈕的回調 
        mDelBtn.setOnClickListener(new OnClickListener() 
        { 
          @Override 
          public void onClick(View v) 
          { 
            if (mListener != null) 
            { 
              mListener.clickHappend(mCurrentViewPos); 
              mPopupWindow.dismiss(); 
            } 
          } 
        }); 
        // Log.e(TAG, "mPopupWindow.getHeight()=" + mPopupWindowHeight); 
 
        break; 
      case MotionEvent.ACTION_UP: 
        isSliding = false; 
 
      } 
      // 相應滑動期間屏幕itemClick事件，避免發生沖突 
      return true; 
    } 
 
    return super.onTouchEvent(ev); 
  } 
 
  /** 
   * 隱藏popupWindow 
   */ 
  private void dismissPopWindow() 
  { 
    if (mPopupWindow != null && mPopupWindow.isShowing()) 
    { 
      mPopupWindow.dismiss(); 
    } 
  } 
 
  public void setDelButtonClickListener(DelButtonClickListener listener) 
  { 
    mListener = listener; 
  } 
 
  interface DelButtonClickListener 
  { 
    public void clickHappend(int position); 
  } 
 
} 

代碼注釋寫得很詳細，簡單說一下，在dispatchTouchEvent中設置當前是否響應用戶滑動，然後在onTouchEvent中判斷是否響應，如果響應則popupWindow以動畫的形式展示出來。當然屏幕上如果存在PopupWindow則屏幕ListView的滾動與Item的點擊，以及從右到左滑動時屏幕Item的click事件。
接下來是MainActivity.java，這裡代碼很簡單不做介紹了。

package com.example.listviewitemslidedeletebtnshow; 
 
import java.util.ArrayList; 
import java.util.Arrays; 
import java.util.List; 
 
import android.app.Activity; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.AdapterView; 
import android.widget.AdapterView.OnItemClickListener; 
import android.widget.ArrayAdapter; 
import android.widget.Toast; 
 
import com.example.listviewitemslidedeletebtnshow.QQListView.DelButtonClickListener; 
 
public class MainActivity extends Activity 
{ 
  private QQListView mListView; 
  private ArrayAdapter<String> mAdapter; 
  private List<String> mDatas; 
 
  @Override 
  protected void onCreate(Bundle savedInstanceState) 
  { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
 
    mListView = (QQListView) findViewById(R.id.id_listview); 
    // 不要直接Arrays.asList 
    mDatas = new ArrayList<String>(Arrays.asList("HelloWorld", "Welcome", "Java", "Android", "Servlet", "Struts", 
        "Hibernate", "Spring", "HTML5", "Javascript", "Lucene")); 
    mAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, mDatas); 
    mListView.setAdapter(mAdapter); 
 
    mListView.setDelButtonClickListener(new DelButtonClickListener() 
    { 
      @Override 
      public void clickHappend(final int position) 
      { 
        Toast.makeText(MainActivity.this, position + " : " + mAdapter.getItem(position), 1).show(); 
        mAdapter.remove(mAdapter.getItem(position)); 
      } 
    }); 
 
    mListView.setOnItemClickListener(new OnItemClickListener() 
    { 
      @Override 
      public void onItemClick(AdapterView<?> parent, View view, int position, long id) 
      { 
        Toast.makeText(MainActivity.this, position + " : " + mAdapter.getItem(position), 1).show(); 
      } 
    }); 
  } 
} 

效果圖如下：樓主使用asm.jar以及gifcamera截的gif，由於button的動畫很短感覺截圖效果很卡不流暢，大家有什麼好的截圖，還望推薦。有興趣的還是下載源碼看看效果i。