这篇文章主要介绍如何写一个Android通用刷新控件，文中介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们一定要看完！
思路：
写一个继承RelativeLayout的RefreshLayout
添加头尾控件作为刷新控件
通过事件分发来进行刷新操作
通过动画来控制控件移动
目的：让他的所有子控件都可以使用，哪怕是一个TextView
public class RefreshLayout extends RelativeLayout { /** * 滑动控件时拉去的速度比例 */ private final int V_REFRESH = 2; /** * 是否是刷新过程 * true 是 * false 不是 * 为false的时候才可以进行刷新 */ private boolean mIsRefreshDuring; /** * 可以进下拉刷新 */ private boolean mCanDownPull; /** * 可以进行上拉刷新 */ private boolean mCanUpPull; /** * 判断触摸后是否是初次移动 */ private boolean mIsFirstMove; /** * y轴呢平移的距离 */ private int mDistanceY; /** * 刷新接口对象 */ private OnRefresh mOnRefresh; /** * 用于控制事件拦截的变量 */ private boolean mCanIntercept; private int mTouchSlop; private int mDistance; private LayoutParams mHeaderParams; private View mHeaderView; private View mFootView; private int mHeaderMaxHeight; private int mStartY; private LayoutParams mFootParams; private int mFootMaxHeight; private PullCallBack mCallBack; private View mChildView; private ObjectAnimator mAnimator; public RefreshLayout(Context context) { super(context); initData(); } public RefreshLayout(Context context, AttributeSet attrs) { super(context, attrs); initData(); } public RefreshLayout(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); initData(); } /** * 必须让头尾控件实现的接口 */ public interface HeadAndFootCallBack { //设置属性 void setAttribute(); //开始刷新 void startPull(); //停止刷新 void stopPull(); } /** * 必须让被拖动的控件子类实现 */ public interface PullCallBack { boolean canDownPull(); boolean canUpPull(); } private void initData() { //不调用该方法不能进行绘制 setWillNotDraw(false); } /** * 下拉刷新完成后必须使用该方法 */ public void downPullFinish() { mAnimator.setFloatValues(mChildView.getTranslationY(), 0); mAnimator.start(); ((HeadAndFootCallBack) mHeaderView).stopPull(); } /** * 上拉完成后必须调用该方法 */ public void upPullFinish() { mAnimator.setFloatValues(mChildView.getTranslationY(), 0); mAnimator.start(); ((HeadAndFootCallBack) mFootView).stopPull(); } /** * 自动下拉刷新 */ public void autoDownPullForHead() { postDelayed(new Runnable() { @Override public void run() { mCanDownPull = true; mCanUpPull = false; mAnimator.setFloatValues(10, mHeaderMaxHeight); mAnimator.start(); ((HeadAndFootCallBack) mHeaderView).startPull(); mOnRefresh.onDownPullRefresh(); } }, 500); } /** * 自动下拉刷新 */ public void autoUpPullForHead() { postDelayed(new Runnable() { @Override public void run() { mCanDownPull = false; mCanUpPull = true; mAnimator.setFloatValues(0, mFootMaxHeight); mAnimator.start(); ((HeadAndFootCallBack) mFootView).startPull(); mOnRefresh.onUpPullRefresh(); } }, 500); } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { return mCanIntercept; } @Override public boolean onTouchEvent(MotionEvent event) { return true; } @Override public boolean dispatchTouchEvent(MotionEvent event) { Log.e("shen", "mIsRefreshDuring=" + mIsRefreshDuring); if (mIsRefreshDuring)/*如果正在进行刷新将不会获取MotionEvent*/ { return super.dispatchTouchEvent(event); } switch (event.getAction()) { case MotionEvent.ACTION_DOWN: mStartY = (int) event.getY(); initPull(); break; case MotionEvent.ACTION_MOVE: if (event.getPointerCount() == 1) { int moveY = (int) event.getY(); mDistanceY = (moveY - mStartY) / V_REFRESH; if (!mIsFirstMove && mDistanceY != 0 && mDistanceY < mTouchSlop) { mCanDownPull = mDistanceY > 0; mCanUpPull = !mCanDownPull; mIsFirstMove = true; } if (mCanDownPull && mCallBack.canDownPull()) { upDataForDownPull();//下拉刷新 mChildView.setEnabled(false); mCanIntercept = true; } if (mCanUpPull && mCallBack.canUpPull()) { upDataForUpPull();//上拉加载 mChildView.setEnabled(false); mCanIntercept = true; } mStartY = moveY; } break; case MotionEvent.ACTION_UP: mIsRefreshDuring = true; mIsFirstMove = false; if (mHeaderParams.height >= mHeaderMaxHeight)/*可以下拉刷新*/ { ((HeadAndFootCallBack) mHeaderView).startPull(); mOnRefresh.onDownPullRefresh(); } else if (mFootParams.height >= mFootMaxHeight)/*可以上拉刷新*/ { ((HeadAndFootCallBack) mFootView).startPull(); mOnRefresh.onUpPullRefresh(); } else if (mHeaderParams.height > 0 && mHeaderParams.height < mHeaderMaxHeight)/*不能进行下拉刷新，收回*/ { releaseForDownFinished(); } else if (mFootParams.height > 0 && mFootParams.height < mFootMaxHeight)/*不能进行下拉刷新，收回*/ { releaseForUpFinished(); } else { mIsRefreshDuring = false; mCanIntercept = false; } break; } super.dispatchTouchEvent(event); return true; } /** * 每次进行触摸都需要进行初始化 */ private void initPull() { mCanDownPull = false; mCanUpPull = false; } /** * 不需要进行上拉刷新 */ private void releaseForUpFinished() { mAnimator.setFloatValues(mChildView.getTranslationY(), 0); mAnimator.start(); } /** * 不需要进行下拉刷新 */ private void releaseForDownFinished() { mAnimator.setFloatValues(mChildView.getTranslationY(), 0); mAnimator.start(); } /** * 上拉时处理手势 */ private void upDataForUpPull() { if (mDistanceY != 0) { mFootParams.height -= mDistanceY; if (mFootParams.height <= 0) { mFootParams.height = 0; } if (mFootParams.height >= mFootMaxHeight) { mFootParams.height = mFootMaxHeight; } mChildView.setTranslationY(-mFootParams.height); mFootView.requestLayout(); } } /** * 下拉时处理手势 */ private void upDataForDownPull() { if (mDistanceY != 0) { mHeaderParams.height += mDistanceY; if (mHeaderParams.height >= mHeaderMaxHeight) { //*** mHeaderParams.height = mHeaderMaxHeight; } if (mHeaderParams.height <= 0) { //最小 mHeaderParams.height = 0; } mChildView.setTranslationY(mHeaderParams.height); mHeaderView.requestLayout(); } } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); } @Override protected void onFinishInflate() { super.onFinishInflate(); //加载头 mHeaderView = getChildAt(0); if (!(mHeaderView instanceof HeadAndFootCallBack)) { new IllegalStateException("HeaderView必须实现HeadAndFootCallBack接口"); } ((HeadAndFootCallBack) mHeaderView).setAttribute(); mHeaderParams = (LayoutParams) mHeaderView.getLayoutParams(); mHeaderParams.addRule(RelativeLayout.ALIGN_PARENT_TOP); //加载尾 mFootView = getChildAt(2); if (!(mFootView instanceof HeadAndFootCallBack)) { new IllegalStateException("FootView必须实现HeadAndFootCallBack接口"); } ((HeadAndFootCallBack) mFootView).setAttribute(); mFootParams = (LayoutParams) mFootView.getLayoutParams(); mFootParams.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM); mChildView = getChildAt(1); if (!(mChildView instanceof HeadAndFootCallBack)) { new IllegalStateException("ChildView必须实现PullCallBack接口"); } mCallBack = (PullCallBack) getChildAt(1); //设置动画 mAnimator = ObjectAnimator.ofFloat(mChildView, "translationY", 0); mAnimator.setInterpolator(new DecelerateInterpolator()); mAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { int translationY = (int) mChildView.getTranslationY(); if (mCanUpPull) { //从移动到的位置往下滑 mFootParams.height = Math.abs(translationY); mFootView.requestLayout(); } else if (mCanDownPull) { mHeaderParams.height = Math.abs(translationY); mHeaderView.requestLayout(); } Log.e("shen", "translationY=" + translationY); Log.e("shen", "mHeaderParams.height=" + mHeaderParams.height); if (translationY == 0) { mChildView.setEnabled(true); mDistanceY = 0; //重置 mIsRefreshDuring = false; //重置 mCanIntercept = false; } else { mIsRefreshDuring = true; } } }); } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop(); mDistance = mTouchSlop * 5; //设置下拉头初始属性 mHeaderMaxHeight = mHeaderParams.height; mHeaderParams.height = 0; mHeaderView.requestLayout(); //设置上拉尾初始属性 mFootMaxHeight = mFootParams.height; mFootParams.height = 0; mFootView.requestLayout(); } /** * 下拉/上拉事件监听 */ public interface OnRefresh { /** * 下拉刷新 */ void onDownPullRefresh(); /** * 上拉加载 */ void onUpPullRefresh(); } public void setOnRefresh(OnRefresh onRefresh) { mOnRefresh = onRefresh; } }给他添加三个控件，头尾就是刷新头、尾，第二个就是正常显示的控件。必须让头尾实现HeadAndFootCallBack接口，来设置属性，通知开始刷新、结束刷新
难点： 现在来说下开发时遇到的难点
由于判断在dispatchTouchEvent中，导致如果该控件以及子控件都不消费该事件的话，就会造成事件不会发送到它，因为如果不消费DOWN事件的话，之后所有的事件都不会在进行接收。解决方式，让该控件onTouchEvent方法消返回true，当子控件不进行事件消费的话，就会返回由该控件消费，不会造成因DOWN事件不消费而无法接收到事件，导致dispatchTouchEvent也不消费事件
动画，动画就是我的伤痛，最近在学习估值器
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