android教你打造独一无二的上拉下拉刷新加载框架

2019-12-12 03:19:50

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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。

我们先看下我们的效果图：

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：SWPullRecyclerLayout_jb51.rar

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。

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