PullToRefreshScrollView踩坑經歷以及原始碼分析
目前下拉重新整理已經滿大街都是，在自己的應用如果不使用這個模式的話，出門都不好意思和人家打招呼
，該文章結合自己使用PullToRefreshScrollView過程中所遇到的問題，簡單探討下針對於github
上的這個開源專案的使用心得，具體的使用方法不做探究。
首先描述下自己使用PullToRefreshScrollView所遇到的BUG現象吧：在ScrollView下拉重新整理時去服務端獲取資料並進行展示，獲取資料的過程採用執行緒池管理執行緒（具體優點兒不做解釋），進行到該步發現一個奇妙的問題，發現一下拉重新整理APP就閃退了，檢視Log錯誤顯示ThreadPoolExecutor佇列滿了RejectedExecutionException，懷疑我的ThreadPoolExecutor容量不夠大，雖擴大至20，再次測試依然閃退，並沒有什麼亂用，仍然是佇列已滿錯誤。之後層層原始碼追看，發現了端倪，onPullDownToRefresh該方法一直不斷的在呼叫，所以導致ThreadPoolExecutor裡面的任務一直變多，導致容量急劇增加，進而閃退。把自己的解決過程記錄下來獻給遇到同樣問題的童鞋。
→代表呼叫的意思
當用戶下拉重新整理並鬆開手指時會呼叫PullToRefreshBase.java的onTouchEvent的case MotionEvent.ACTION_UP→PullToRefreshBase.java的final void setState(State state, final boolean... params)其PullToRefreshBase.java的中state=MANUAL_REFRESHING，params=[true]→PullToRefreshBase.java的protected
void onRefreshing(final boolean doScroll) 其中doScroll=true→PullToRefreshBase.java的protected final void smoothScrollTo(int scrollValue, OnSmoothScrollFinishedListener listener)→PullToRefreshBase.java的private final void smoothScrollTo(int newScrollValue, long
duration, long delayMillis,OnSmoothScrollFinishedListener listener)→PullToRefreshBase.java的public SmoothScrollRunnable(int fromY, int toY, long duration, OnSmoothScrollFinishedListener listener)例項化一個執行緒→PullToRefreshBase.java的post(mCurrentSmoothScrollRunnable);執行SmoothScrollRunnable執行緒從SmoothScrollRunnable內部原始碼
首先將HeaderView採用postOnAnimation慢慢的隱藏掉，直到HeaderView隱藏掉之後mScrollToY == mCurrentY然後呼叫mListener.onSmoothScrollFinished()，該方法最終呼叫onPullDownToRefresh方法，如果onPullDownToRefresh裡面開啟一個執行緒去服務端獲取資料，因為獲取資料和SmoothScrollRunnable不在一個執行緒中，那麼此時SmoothScrollRunnable獲得時間片它的run方法會不斷的執行，因此mListener.onSmoothScrollFinished()會不斷的執行，所以會導致不停地向ThreadPoolExecutor提交任務，所以ThreadPoolExecutor容量會瞬間變滿導致異常。因此考慮在SmoothScrollRunnable當中增加一個標誌位，標誌我當次已經在初始化中，具體程式碼如下，紅色是新增的邏輯。final class SmoothScrollRunnable implements Runnable { private final Interpolator mInterpolator; private final int mScrollToY; private final int mScrollFromY; private final long mDuration; private OnSmoothScrollFinishedListener mListener; private boolean mContinueRunning = true; private long mStartTime = -1; private int mCurrentY = -1; public SmoothScrollRunnable(int fromY, int toY, long duration, OnSmoothScrollFinishedListener listener) { Log.i("TTT", " SmoothScrollRunnable 例項化"); mScrollFromY = fromY; mScrollToY = toY; mInterpolator = mScrollAnimationInterpolator; mDuration = duration; mListener = listener; } @Override public void run() { /** * Only set mStartTime if this is the first time we're starting, * else actually calculate the Y delta */ if (mStartTime == -1) { mStartTime = System.currentTimeMillis(); Log.i("TTT", " mStartTime=" + mStartTime); } else { /** * We do do all calculations in long to reduce software float * calculations. We use 1000 as it gives us good accuracy and * small rounding errors */ long normalizedTime = (1000 * (System.currentTimeMillis() - mStartTime)) / mDuration; normalizedTime = Math.max(Math.min(normalizedTime, 1000), 0); final int deltaY = Math.round((mScrollFromY - mScrollToY) * mInterpolator.getInterpolation(normalizedTime / 1000f)); mCurrentY = mScrollFromY - deltaY; setHeaderScroll(mCurrentY); Log.i("TTT", " normalizedTime=" + normalizedTime + ", mContinueRunning=" + mContinueRunning + ",mScrollToY=" + mScrollToY + ",mCurrentY=" + mCurrentY); } // If we're not at the target Y, keep going... if (mContinueRunning && mScrollToY != mCurrentY) { ViewCompat.postOnAnimation(PullToRefreshBase.this, this); } else { if (null != mListener) { Log.i("TTT", "mListener.onSmoothScrollFinished(),isSmoothScrollFinished=" + isSmoothScrollFinished); mListener.onSmoothScrollFinished(); } } } public void stop() { Log.i("TTT", " stop()"); mContinueRunning = false; removeCallbacks(this); } }
final class SmoothScrollRunnable implements Runnable
{
private final Interpolator mInterpolator;
private final int mScrollToY;
private final int mScrollFromY;
private final long mDuration;
private OnSmoothScrollFinishedListener mListener;
private boolean mContinueRunning = true;
private long mStartTime = -1;
private int mCurrentY = -1;
<span style="color:#FF0000;">private boolean isSmoothScrollFinished = false;</span>
public SmoothScrollRunnable(int fromY, int toY, long duration, OnSmoothScrollFinishedListener listener)
{
Log.i("TTT", " SmoothScrollRunnable 例項化");
mScrollFromY = fromY;
mScrollToY = toY;
mInterpolator = mScrollAnimationInterpolator;
mDuration = duration;
mListener = listener;
}
@Override
public void run()
{
/**
* Only set mStartTime if this is the first time we're starting,
* else actually calculate the Y delta
*/
if (mStartTime == -1)
{
mStartTime = System.currentTimeMillis();
Log.i("TTT", " mStartTime=" + mStartTime);
}
else
{
/**
* We do do all calculations in long to reduce software float
* calculations. We use 1000 as it gives us good accuracy and
* small rounding errors
*/
long normalizedTime = (1000 * (System.currentTimeMillis() - mStartTime)) / mDuration;
normalizedTime = Math.max(Math.min(normalizedTime, 1000), 0);
final int deltaY =
Math.round((mScrollFromY - mScrollToY) * mInterpolator.getInterpolation(normalizedTime / 1000f));
mCurrentY = mScrollFromY - deltaY;
setHeaderScroll(mCurrentY);
Log.i("TTT",
" normalizedTime=" + normalizedTime + ", mContinueRunning=" + mContinueRunning + ",mScrollToY="
+ mScrollToY + ",mCurrentY=" + mCurrentY);
}
// If we're not at the target Y, keep going...
if (mContinueRunning && mScrollToY != mCurrentY)
{
ViewCompat.postOnAnimation(PullToRefreshBase.this, this);
}
else
{
if (null != mListener)
{
Log.i("TTT", "mListener.onSmoothScrollFinished(),isSmoothScrollFinished=" + isSmoothScrollFinished);
<span style="color:#FF0000;">if (!isSmoothScrollFinished)</span>
<span style="color:#FF0000;">{</span>
mListener.onSmoothScrollFinished();
<span style="color:#FF0000;">}</span>
<span style="color:#FF0000;">isSmoothScrollFinished = true;</span>
}
}
}
public void stop()
{
Log.i("TTT", " stop()");
mContinueRunning = false;
<span style="color:#FF0000;">isSmoothScrollFinished = true;</span>
removeCallbacks(this);
}
}