PullToRefreshScrollView踩坑经历以及源码分析
目前下拉刷新已经满大街都是，在自己的应用如果不使用这个模式的话，出门都不好意思和人家打招呼，该文章结合自己使用PullToRefreshScrollView过程中所遇到的问题，简单探讨下针对于github 上的这个开源项目的使用心得，具体的使用方法不做探究。
首先描述下自己使用PullToRefreshScrollView所遇到的BUG现象吧：在ScrollView下拉刷新时去服务端获取数据并进行展示，获取数据的过程采用线程池管理线程（具体优点儿不做解释），进行到该步发现一个奇妙的问题，发现一下拉刷新APP就闪退了，查看Log错误显示ThreadPoolExecutor队列满了RejectedExecutionException，怀疑我的ThreadPoolExecutor容量不够大，虽扩大至20，再次测试依然闪退，并没有什么乱用，仍然是队列已满错误。之后层层源码追看，发现了端倪，onPullDownToRefresh该方法一直不断的在调用，所以导致ThreadPoolExecutor里面的任务一直变多，导致容量急剧增加，进而闪退。把自己的解决过程记录下来献给遇到同样问题的童鞋。
→代表调用的意思
当用户下拉刷新并松开手指时会调用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)实例化一个线程→PullToRefreshBase.java的post(mCurrentSmoothScrollRunnable);运行SmoothScrollRunnable线程从SmoothScrollRunnable内部源码
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 实例化");
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;
private boolean isSmoothScrollFinished = false;
public SmoothScrollRunnable(int fromY, int toY, long duration, OnSmoothScrollFinishedListener listener)
{
Log.i("TTT", " SmoothScrollRunnable 实例化");
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);
if (!isSmoothScrollFinished)
{
mListener.onSmoothScrollFinished();
}
isSmoothScrollFinished = true;
}
}
}
public void stop()
{
Log.i("TTT", " stop()");
mContinueRunning = false;
isSmoothScrollFinished = true;
removeCallbacks(this);
}
}