Android控件PullRefreshViewGroup实现下拉刷新和上拉加载

@Override  public boolean onInterceptTouchEvent(MotionEvent ev) {   boolean bret = false;   switch (ev.getAction()) {    case MotionEvent.ACTION_DOWN: {     mPreY = ev.getY();     Log.d(TAG, "mPreY:" + String.valueOf(mPreY));    }    break;    case MotionEvent.ACTION_MOVE: {     float curY = ev.getY();     float distance = curY - mPreY;     if (Math.abs(distance) >= mTouchSlop) {      mSliding = bret = true;       //修正第一次滑动的卡顿      if (distance > 0) {       mPreY += mTouchSlop;      } else {       mPreY -= mTouchSlop;      }       if (!mScroller.isFinished()) {       mScroller.abortAnimation();      }     } else {      mSliding = bret = false;     }    }    break;    case MotionEvent.ACTION_UP:    case MotionEvent.ACTION_CANCEL: {     bret = mSliding;    }    break;   }   return bret ? true : super.onInterceptTouchEvent(ev);  }   @Override  public boolean onTouchEvent(MotionEvent event) {   boolean bret = false;    vTracker.addMovement(event);    switch (event.getAction()) {    case MotionEvent.ACTION_DOWN: {     mPreY = event.getY();     bret = true;    }    break;    case MotionEvent.ACTION_MOVE: {     float curY = event.getY();     float distance = curY - mPreY;     Log.d(TAG, "mPreY:" + String.valueOf(mPreY) + " distance:" + String.valueOf(distance));     if (distance != 0) {      bret = true;       if (mSrcHeightHead == -1 && mHasPullRefresh) {       View child0View = mHeadView;       mSrcHeightHead = child0View.getHeight();      }       scrollBy(distance);     }      mPreY = curY;    }    break;    case MotionEvent.ACTION_UP:    case MotionEvent.ACTION_CANCEL: {     mPreCurY = 0;      View child0View = mHeadView;     int child0Height = null != child0View ? child0View.getHeight() : 0;     int child0Height2 = null != child0View ? child0View.getLayoutParams().height : 0; //视图的最终高度是有这个来决定的,请看onMeasure 函数的实现     // int child0Height3 = child0View.getMeasuredHeight();     if (child0Height2 != child0Height) {      child0Height = child0Height2;     }     int child0Top = null != child0View ? child0View.getTop() : 0;     int dy = child0Height - mSrcHeightHead + (mSrcHeightHead - Math.abs(child0Top));     Log.d(TAG, "onTouchEvent()ACTION_UP child0Height:" + String.valueOf(child0Height) + " mSrcHeightHead:" + String.valueOf(mSrcHeightHead) + " child0Top:" + String.valueOf(child0Top));     if (dy > 0) {//恢复拉伸视图的位置      if (!mLoadingMore && dy > mCanRefreshHeight && child0Top + child0Height2 > mCanRefreshHeight && mRefreshLoad != null) {       dy -= mCanRefreshHeight;        if (!mPullRefreshLoading) {        mPullRefreshLoading = true;        mTvRefreshInfo.setText("正在加载...");        mRefreshLoad.pullRefreshStartLoad();       }      }      mScroller.startScroll(0, 0, 0, -dy);      invalidate();     } else {      vTracker.computeCurrentVelocity(1000);       float yvel = vTracker.getYVelocity();      if (yvel != 0) {//为了满足内部视图的快速滚动( 中间内容视图 )       mScroller.fling(0, 0, 0, (int) yvel, 0, 0, Integer.MIN_VALUE, Integer.MAX_VALUE);       invalidate();      }     }      vTracker.clear();     bret = true;    }    break;   }   return bret ? true : super.onTouchEvent(event);  } 

private void scrollBy(float distance) {   View child0View = mHeadView;   View child1View = getChildAt(null == mHeadView ? 0 : 1);   float distanceRemain = 0;    int child0Top = null != child0View ? child0View.getTop() : 0;   // int child0Height = child0View.getHeight();    if (distance < 0) {//向上    int child1Top = child1View.getTop();    // int child1Height = child1View.getHeight();     //child0View 缩小    if (-1 != mSrcHeightHead && null != child0View && child0View.getHeight() > mSrcHeightHead) {     float off = distance;     if (child0View.getHeight() + distance < mSrcHeightHead) {      off = -(child0View.getHeight() - mSrcHeightHead);      distance -= off;     } else {      distance = 0;     }      child0View.getLayoutParams().height += (int) off;     child1Top += (int) off; //child0view 缩小的同时, child1view 的高度也会随之上升 这里很重要     requestLayout();     child1View.offsetTopAndBottom((int) off);     if (null != mTailView) {      mTailView.offsetTopAndBottom((int) off);     }    }     if (distance != 0) {     if (child0Top + mSrcHeightHead + distance <= 0) {      distanceRemain = -(distance + (child0Top + mSrcHeightHead));//正数      distance = -(child0Top + mSrcHeightHead);//负数     }      //可以显示加载更多吗?     boolean bDirectDown = false;     boolean bCanScroll = child1View.canScrollVertically(1) || child1View.canScrollVertically(-1);     if (!bCanScroll) {      int child1ChildCount = 0;      if (child1View instanceof ViewGroup) {       child1ChildCount = ((ViewGroup) child1View).getChildCount();      }      if (child1ChildCount > 0) {       ViewGroup viewGroupChild1 = (ViewGroup) child1View;        View child1LastItem = viewGroupChild1.getChildAt(child1ChildCount - 1);       int child1ViewBottom = viewGroupChild1.getBottom();       int child1LastItemBottom = child1LastItem.getBottom() + child1Top; //相对于 ImageScaleViewGroup 的位置       //增加 child1ViewBottom > getHeight() 来控制 ScrollView       if (child1LastItemBottom == getHeight()) {        bDirectDown = true;       }      }     }     //正在下拉刷新的时候,不能显示加载更多     if ((bCanScroll || bDirectDown) && null != mTailView && !mPullRefreshLoading) {       int nVerticalScrollExtent = 0, nVerticalScrollRange = 0, nVerticalScrollOffset = 0;      Class c = null;       try {       c = Class.forName(child1View.getClass().getName());      } catch (Exception ex) {       }      try {       if (null == mComputeVerticalScrollExtent) {        Method computeVerticalScrollExtent = findcomputeVerticalMethod(c, "computeVerticalScrollExtent");        computeVerticalScrollExtent.setAccessible(true);        mComputeVerticalScrollExtent = computeVerticalScrollExtent;       }       nVerticalScrollExtent = (int) mComputeVerticalScrollExtent.invoke(child1View);      } catch (Exception ex) {       }      try {       if (null == mComputeVerticalScrollRange) {        Method computeVerticalScrollRange = findcomputeVerticalMethod(c, "computeVerticalScrollRange");        computeVerticalScrollRange.setAccessible(true);        mComputeVerticalScrollRange = computeVerticalScrollRange;       }        nVerticalScrollRange = (int) mComputeVerticalScrollRange.invoke(child1View);      } catch (Exception ex) {       }      try {       if (null == mComputeVerticalScrollOffset) {        Method computeVerticalScrollOffset = findcomputeVerticalMethod(c, "computeVerticalScrollOffset");        computeVerticalScrollOffset.setAccessible(true);        mComputeVerticalScrollOffset = computeVerticalScrollOffset;       }       nVerticalScrollOffset = (int) mComputeVerticalScrollOffset.invoke(child1View);      } catch (Exception ex) {       }        int range = nVerticalScrollRange - nVerticalScrollExtent;      if (nVerticalScrollOffset + distanceRemain > range) {       float nOff = distanceRemain - (range - nVerticalScrollOffset);        distanceRemain = range - nVerticalScrollOffset;       distance -= nOff;      }       int child3Bottom = mTailView.getBottom();       if (child3Bottom + distance < getHeight()) {       distance = getHeight() - child3Bottom;      }     }      if (!bCanScroll) {      distanceRemain = 0;     }    }    } else {//向下    int nScrollOffset = 0;    try {     Class c = Class.forName(child1View.getClass().getName());     Method computeVerticalScrollOffset = findcomputeVerticalMethod(c, "computeVerticalScrollOffset");//c.getDeclaredMethod("computeVerticalScrollOffset");     computeVerticalScrollOffset.setAccessible(true);     nScrollOffset = (int) computeVerticalScrollOffset.invoke(child1View);    } catch (Exception ex) {     }     int child2Top = null != mTailView ? mTailView.getTop() : getHeight();//注意默认值    if (child2Top < getHeight()) {     if (child2Top + distance > getHeight()) {      distanceRemain = distance - (getHeight() - child2Top);      distance = getHeight() - child2Top;     }    } else if (nScrollOffset > 0) {//内部有滚动,那么就要计算内部滚动距离,其他分配给整体滚动     if (nScrollOffset - distance <= 0) {      distanceRemain = -nScrollOffset;      // distance = distance - nScrollOffset;      distance = 0; //内部能滚动,不让外部去滚动      if (!mScroller.isFinished()) {       mScroller.abortAnimation(); //内部滚动完后,立即停止      }     } else {      distanceRemain = -distance;//负数      distance = 0;     }    } else {     if (child0Top + distance > 0) {//child0放大,child1移动      int off = (int) (child0Top + distance);      distance = -child0Top;       if (null != child0View) {       child0View.getLayoutParams().height += off;       requestLayout();      } else {       off = 0;      }       child1View.offsetTopAndBottom(off);      if (null != mTailView) {       mTailView.offsetTopAndBottom(off);      }     }    }   }    if (0 != (int) distance) {    if (null != child0View) {     child0View.offsetTopAndBottom((int) distance);    }    child1View.offsetTopAndBottom((int) distance);    if (null != mTailView) {     mTailView.offsetTopAndBottom((int) distance);    }     requestLayout();//奇酷360这里必须调用, 否则显示有点问题   }    scrollByForMidView(distanceRemain);//外部无法滚动的时候,内部滚动    if (!mPullRefreshLoading && !mLoadingMore) {    int tailviewTop = null != mTailView ? mTailView.getTop() : getHeight();//注意默认值     if (tailviewTop < getHeight() && mHasLoadMore) {//加载更多     mLoadingMore = true;     if (mRefreshLoad != null) {      mRefreshLoad.pullUpStartLoadMore();     }    } else {     if (mHasPullRefresh) {      if (distance < 0) {       int child0Bottom = child0View.getBottom();       if (child0Bottom < mCanRefreshHeight) {        mTvRefreshInfo.setText("下拉刷新");       }      } else {       int child0Bottom = child0View.getBottom();       if (child0Bottom > mCanRefreshHeight) {        mTvRefreshInfo.setText("松开刷新");       }      }     }    }   }  } 

private void scrollByForMidView(float distanceRemain) {   if (0 != (int) distanceRemain) {    View child1View = getChildAt(null == mHeadView ? 0 : 1);    if (child1View instanceof ListView) {     ((ListView) child1View).smoothScrollBy((int) distanceRemain, 0);    } /*else if (child1View instanceof ScrollView){     ((ScrollView) child1View).smoothScrollBy(0,(int) distanceRemain);    }*/ else {     child1View.scrollBy(0, (int) distanceRemain);    }   }  }