项目中我们经常有上拉、下拉刷新的需求，几乎所有的listView、RecyclerView都会伴随着上拉、下拉刷新的需求，如果我们使用一些开源控件，换了控件我们就要更新，现在我们自己撸起袖子写一个通用的刷新控件
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) { //最大
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
这个控件自认为写的不错，通过他可以帮我们学习事件分发、动画、接口回调，也是有一定的学习意义
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