参考Android仿腾讯QQ实现滑动删除这篇文章进行学习，文章实现的功能是:在ListView的Item上从右向左滑时，出现删除按钮，点击删除按钮把Item删除，效果
看过文章后，感觉没有必要把dispatchTouchEvent()和onTouchEvent()两个方法都重写，只要重写onTouchEvent就好了。于是对代码作了一些调整：
public class MyListView extends ListView { private static final String TAG = "MyListView"; private int mTouchSlop; private int mXDown; private int mYDown; private int mCurrentPosition; private View mCurrentView; private PopupWindow mPopupWindow; private LayoutInflater mInflater; private boolean isSliding = false; // 为删除按钮提供一个回调接口 private DelButtonClickListener mListener; private Button mDelBtn; private int mPopupWindowHeight; private int mPopupWindowWidth; public MyListView(Context context, AttributeSet attrs) { super(context, attrs); mInflater = LayoutInflater.from(context); mTouchSlop = 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); // 如果需要通过点击PopupWindow之外的地方使其消失，则需要setFocusable(true). mPopupWindow.setFocusable(true); // Android 6.0以前的版本需要setBackgroundDrawable()， // 才能实现通过点击PopupWindow之外的地方使其消失的功能。 mPopupWindow.setBackgroundDrawable(new ColorDrawable(0)); // 先调用下measure，否则拿不到宽和高 mPopupWindow.getContentView().measure(0, 0); mPopupWindowHeight = mPopupWindow.getContentView().getMeasuredHeight(); mPopupWindowWidth = mPopupWindow.getContentView().getMeasuredWidth(); } @Override public boolean onTouchEvent(MotionEvent ev) { int action = ev.getAction(); int x = (int) ev.getX(); int y = (int) ev.getY(); switch (action){ case MotionEvent.ACTION_DOWN: isSliding = false; mXDown = x; mYDown = y; mCurrentPosition = pointToPosition(mXDown, mYDown); View view = getChildAt(mCurrentPosition - getFirstVisiblePosition()); mCurrentView = view; break; case MotionEvent.ACTION_MOVE: int dx = x - mXDown; int dy = y - mYDown; Log.d(TAG, "mTouchSlop = " + mTouchSlop + ", dx = " + dx + ", dy = " + dy); if(mXDown > x && Math.abs(dx) > mTouchSlop && Math.abs(dy) < mTouchSlop){ Log.d(TAG, "isSliding"); isSliding = true; int[] location = new int[2]; mCurrentView.getLocationOnScreen(location); mPopupWindow.setAnimationStyle(R.style.popwindow_delete_btn_anim_style); mPopupWindow.update(); Log.d(TAG, "Height: " + mCurrentView.getHeight() + "," + mPopupWindow.getHeight()); mPopupWindow.showAtLocation(mCurrentView, Gravity.NO_GRAVITY, location[0] + mCurrentView.getWidth(), location[1] + mCurrentView.getHeight() / 2 - mPopupWindowHeight / 2); mDelBtn.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { mListener.clickHappend(mCurrentPosition); mPopupWindow.dismiss(); } }); } case MotionEvent.ACTION_UP: // isSliding 如果这里恢复为false,则后面会执行super.onTouchEvent事件， // 而AbsListView的onTouchEvent调用了onTouchUp方法，在onTouchUp方法中有可能执行 // performClick.run() --> performItemClick() --> super.performItemClick // --> mOnItemClickListener.onItemClick，这样最终触发Item的点击。 // 因此此处依旧保持isSliding为true的状态，而在ACTION_DOWN事件中恢复isSliding为false， // 毕竟每个事件都以ACTION_DOWN开始。 //isSliding = false; } if(isSliding){ return true; } return super.onTouchEvent(ev); } public void setDelButtonClickListener(DelButtonClickListener listener){ mListener = listener; } interface DelButtonClickListener{ public void clickHappend(int position); }}
通过这个例子学习到：1、ListView的Item点击事件的触发过程：自定义ListView的onTouchEvent() —调用super.onTouchEvent()—> AbsListView.onTouchEvent() —MotionEvent.ACTION_UP—> AbsListView.onTouchUp()—(有可能)调用performClick.run()—> AbsListView.PerformClick.run() —调用performItemClick()—> AbsListView.performItemClick()
—(有可能)调用super.performItemClick()—> AdapterView.performItemClick() —mOnItemClickListener.onItemClick—> OnItemClickListener.onItemClick()也就是Item的点击事件是在MotionEvent.ACTION_UP事件完成的，这样在自定义ListView的onTouchEvent()中，对MotionEvent.ACTION_UP直接return true消费掉事件，而不要调用super.onTouchEvent。这样就避免了删除按钮与Item点击事件的冲突。
2、PopupWindow–通过点击PopupWindow之外的地方使其消失a、需要调用setFocusable()方法（PopupWindow中showAtLocation() –> createPopupLayoutParams() –> computeFlags() –> 设置FLAG_NOT_FOCUSABLE）；b、Android 6.0以前的版本需要setBackgroundDrawable()（具体原因见：PopupWindow的使用）。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。
而不去欣赏今天就开在我们窗口的玫瑰。
