Android 教你打造独一无二的刷新加载框架

【Android 教你打造独一无二的刷新加载框架】幽沉谢世事，俯默窥唐虞。这篇文章主要讲述Android 教你打造独一无二的刷新加载框架相关的知识，希望能为你提供帮助。
其实早在去年七月，群里小伙伴就有让我共享这个。但我当时绝的技术不纯熟。代码有bug什么的。没有写出来。现在感觉整理的差不多了。就写出来让大家看看，有问题一起讨论解决。
说到刷新加载，我们第一个想到啥，对了就是swiperefreshlayout，还有什么SuperSwiperefreshlayout， XRecyclerView等等。反正老多了，我还是之前那句话，不管用什么，我们需要知道他的原理。
打造框架开始对于刷新加载的实现，你们第一个想到的是什么？是用swiperefresh然后在recyclerview底部加一个不同type？还是用事件拦截呢？那必须是事件拦截啊，虽然现在swiperefreshlayout很火，基本很多app都能看到他。但是遇到那种坑比公司说刷新要用自己公司logo你也没辙。对把。。好了，感觉得罪了好多公司，不管他，我们继续。
如果有小伙伴长期看我博客，应该知道我前面有一篇是写过事件拦截的。没错，就是从源码角度分析嵌套滑动机制NestedScrolling
对于nestedscrolling不了解的同学可以看完在继续下文。
我们先看下我们的效果图：

文章图片

老铁，没毛病。下面我介绍如何实现的。
下拉刷新首先我们给出如下几个参数，后面要用：

private NestedScrollingParentHelper helper = null; private boolean IsRefresh = true; private boolean IsLoad = true; //滑动的总距离 private int totalY = 0; private LinearLayout headerLayout = null; private MyRecyclerView myRecyclerView = null; private LinearLayout footerLayout = null;

既然是刷新，我们的滚动肯定是在父view之前的。所以我们需要在onNestedPreScroll这个方法里面写上我们所需要改动的x， y值。
我们需要用父view去拦截它。
我们需要判断dy的值是否大于0，因为大于0是刷新操作，小于0是加载操作。然后我们需要判断recyclerview是否是纵向的而不是横向的。

public void onNestedPreScroll(View target, int dx, int dy, int[] consumed) { if (IsRefresh) { if (dy > 0) { if (myRecyclerView.isOrientation(0)) { totalY + = dy; if ((totalY / 2) < = 0) { scrollTo(0, totalY / 2); consumed[1] = dy; } else { scrollTo(0, 0); consumed[1] = 0; } } return; } }

上拉加载上面我也说了onNestedPreScroll这个方法中判断dy< 0才是加载操作。所以综上所述，代码变成了这样：

public void onNestedPreScroll(View target, int dx, int dy, int[] consumed) { if (totalY < 0 & & myRecyclerView.isOrientation(0) || totalY > 0 & & myRecyclerView.isOrientation(1)) { isfling = true; } if (IsRefresh) { if (dy > 0) { if (myRecyclerView.isOrientation(0)) { totalY + = dy; if ((totalY / 2) < = 0) { scrollTo(0, totalY / 2); consumed[1] = dy; } else { scrollTo(0, 0); consumed[1] = 0; } } return; } } if (IsLoad) { if (dy < 0) { if (myRecyclerView.isOrientation(1)) { totalY + = dy; if ((totalY / 2) > = 0) { scrollTo(0, totalY / 2); consumed[1] = dy; } else { scrollTo(0, 0); consumed[1] = 0; } } return; } } }

最后我们需要在子view滑动结束后，实行如下操作：

//子view滑动结束调用 //dyUnconsumed < 0 向下滚 //dyUnconsumed > 0 向上滚 public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) { if (dyUnconsumed != 0) { totalY + = dyUnconsumed; scrollTo(0, totalY / 2); } }

其实最主要的两个方法已经解决了，其他到没什么了，这边，我把nestedscrolling的8个接口的功能和自定义recyclerview放出来。已变大家参考。希望大家都能实现自己的刷新加载。告别swiperefreshlayout。
添加header和footer 这里我们参考listview自带的addheaderview和addfooterview。代码如下：

public void addHeaderView(View headerView, int headerHeight) { this.headerLayout.removeAllViews(); this.headerLayout.addView(headerView); LayoutParams layoutParams = new LayoutParams(LayoutParams.MATCH_PARENT, headerHeight); layoutParams.topMargin = -headerHeight; this.headerLayout.setLayoutParams(layoutParams); }public void addFooterView(View footerView, int footerHeight) { this.footerLayout.removeAllViews(); this.footerLayout.addView(footerView); this.footerLayout.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, footerHeight)); }

几个接口的实现

public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) { return true; }public void onNestedScrollAccepted(View child, View target, int axes) { helper.onNestedScrollAccepted(child, target, axes); }//父view拦截子view的滚动 public void onNestedPreScroll(View target, int dx, int dy, int[] consumed) { if (totalY < 0 & & myRecyclerView.isOrientation(0) || totalY > 0 & & myRecyclerView.isOrientation(1)) { isfling = true; } if (IsRefresh) { if (dy > 0) { if (myRecyclerView.isOrientation(0)) { totalY + = dy; if ((totalY / 2) < = 0) { scrollTo(0, totalY / 2); consumed[1] = dy; } else { scrollTo(0, 0); consumed[1] = 0; } } return; } } if (IsLoad) { if (dy < 0) { if (myRecyclerView.isOrientation(1)) { totalY + = dy; if ((totalY / 2) > = 0) { scrollTo(0, totalY / 2); consumed[1] = dy; } else { scrollTo(0, 0); consumed[1] = 0; } } return; } } }//子view滑动结束调用 //dyUnconsumed < 0 向下滚 //dyUnconsumed > 0 向上滚 public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) { if (dyUnconsumed != 0) { totalY + = dyUnconsumed; scrollTo(0, totalY / 2); } }public void onStopNestedScroll(View child) { helper.onStopNestedScroll(child); if (onTouchUpListener != null) { isfling = false; onTouchUpListener.touchUp(); } }public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed) { return isfling; }public boolean onNestedPreFling(View target, float velocityX, float velocityY) { return isfling; }public int getNestedScrollAxes() { return helper.getNestedScrollAxes(); }

自定义recyclerview
既然是自己写的刷新加载框架，总不能还有自定义layout中在放个recyclerview。多麻烦，自定义一个，直接放在里面，然后分别放个header和footer 就没必要每次有页面用到刷新都要写一个布局。3个布局解决整个项目的刷新和加载。话不多说，代码如下：

private class MyRecyclerView extends RecyclerView { private StaggeredGridLayoutManager staggeredGridLayoutManager = null; private LinearLayoutManager linearLayoutManager = null; private GridLayoutManager gridLayoutManager = null; private boolean isScrollLoad = false; private boolean isScrollRefresh = false; public MyRecyclerView(Context context) { super(context); setVerticalFadingEdgeEnabled(false); setHorizontalFadingEdgeEnabled(false); setVerticalScrollBarEnabled(false); setHorizontalScrollBarEnabled(false); setOverScrollMode(OVER_SCROLL_NEVER); setItemAnimator(new DefaultItemAnimator()); }private void setMyLayoutManager(LayoutManager layoutManager) { if (layoutManager instanceof StaggeredGridLayoutManager) { staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager; } else if (layoutManager instanceof GridLayoutManager) { gridLayoutManager = (GridLayoutManager) layoutManager; } else if (layoutManager instanceof LinearLayoutManager) { linearLayoutManager = (LinearLayoutManager) layoutManager; } setLayoutManager(layoutManager); if (!isVertical()) { throw new NullPointerException(" vertical!" ); } }private boolean isOrientation(int orientation) {//orientation,0代表向下， 1代表向上 if (orientation = = 0) return isCanPullDown(); else if (orientation = = 1) return isCanPullUp(); return false; }private boolean isCanPullDown() { return !canScrollVertically(-1); }private boolean isCanPullUp() { return !canScrollVertically(1); }//private int scrollLoad() { //int lastItem = 0; //int itemCount = 0; //int spanCount = 1; //if (staggeredGridLayoutManager != null) { //lastItem = staggeredGridLayoutManager.findLastVisibleItemPositions(null)[0]; //itemCount = staggeredGridLayoutManager.getItemCount(); //spanCount = staggeredGridLayoutManager.getSpanCount(); //} else if (linearLayoutManager != null) { //lastItem = linearLayoutManager.findLastVisibleItemPosition(); //itemCount = linearLayoutManager.getItemCount(); //spanCount = 1; //} else if (gridLayoutManager != null) { //lastItem = gridLayoutManager.findLastVisibleItemPosition(); //itemCount = gridLayoutManager.getItemCount(); //spanCount = gridLayoutManager.getSpanCount(); //} //return ((itemCount - 1) / spanCount + 1) - (lastItem / spanCount + 1); //}private boolean isVertical() { if (staggeredGridLayoutManager != null) return staggeredGridLayoutManager.getOrientation() = = StaggeredGridLayoutManager.VERTICAL; else if (linearLayoutManager != null) return linearLayoutManager.getOrientation() = = LinearLayoutManager.VERTICAL; else if (gridLayoutManager != null) return gridLayoutManager.getOrientation() = = GridLayoutManager.VERTICAL; return false; }//public void onScrolled(int dx, int dy) { //if (dy > 0 & & !isScrollLoad) { //if (oLior != null) { //onScrollListener.scrollLoad(sc` ` ` ` ` ` ` ` ` ` ` llLoad()); //传递滚动到倒数第几行 //} //} //} }

这样我们变实现了自己的刷新加载框架，代码我已上传到github： https://github.com/sw950729/SWPullRecyclerLayout
至于使用方法如下：
jcenter：

compile ' com.angel:SWPullRecyclerLayout:1.0.0'

maven：

< dependency> < groupId> com.angel< /groupId> < artifactId> SWPullRecyclerLayout< /artifactId> < version> 1.0.0< /version> < type> pom< /type> < /dependency>

明天正式上班，上班之前把这篇干货分享给大家。依旧是那2句话。不管用什么我们需要知道原理。还有就是有什么不懂的提出来。可以一起讨论。