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 {
void setAttribute();
void startPull();
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() {
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) {
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();
mChildView.setEnabled(false);
mCanIntercept = true;
}
if (mCanUpPull && mCallBack.canUpPull()) {
upDataForUpPull();
mChildView.setEnabled(false);
mCanIntercept = true;
}
mStartY = moveY;
}
break;
case MotionEvent.ACTION_UP:
mIsRefreshDuring = true;
mIsFirstMove = false;
if (mHeaderParams.height >= mHeaderMaxHeight) {
((HeadAndFootCallBack) mHeaderView).startPull();
mOnRefresh.onDownPullRefresh();
} else if (mFootParams.height >= mFootMaxHeight) {
((HeadAndFootCallBack) mFootView).startPull();
mOnRefresh.onUpPullRefresh();
} else if (mHeaderParams.height > 0 && mHeaderParams.height < mHeaderMaxHeight) {
releaseForDownFinished();
} else if (mFootParams.height > 0 && mFootParams.height < mFootMaxHeight) {
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) {
mHeaderParams.height = 0;
}
mChildView.setTranslationY(mHeaderParams.height);
mHeaderView.requestLayout();
}
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
}
@Override
protected void onFinishInflate() {
super.onFinishInflate();
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);
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);
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) {
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;
mIsRefreshDuring = false;
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;
mHeaderMaxHeight = mHeaderParams.height;
mHeaderParams.height = 0;
mHeaderView.requestLayout();
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;
}
}
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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
/4 
