概述
RecyclerView出现已经有一段时间了,相信大家肯定不陌生了,大家可以通过导入support-v7对其进行使用。
据官方的介绍,该控件用于在有限的窗口中展示大量数据集,其实这样功能的控件我们并不陌生,例如:ListView、GridView。
那么有了ListView、GridView为什么还需要RecyclerView这样的控件呢?整体上看RecyclerView架构,提供了一种插拔式的体验,高度的解耦,异常的灵活,通过设置它提供的不同LayoutManager,ItemDecoration , ItemAnimator实现令人瞠目的效果。
- 你想要控制其显示的方式,请通过布局管理器LayoutManager
- 你想要控制Item间的间隔(可绘制),请通过ItemDecoration
- 你想要控制Item增删的动画,请通过ItemAnimator
- 你想要控制点击、长按事件,请自己写(擦,这点尼玛。)
一.RecyclerView介绍
RecyclerView 是Android 5.0版本中新出现的东西,用来替代ListView和GridView的。
二.RecyclerView架构
RecyclerView使用布局管理器LayoutManager和适配器Adapter的适配器模式去实现架构,不关心数据的来源。耦合性非常的底,用户可以根据自己的用户界面去实现相应的效果
三.RecyclerView的优点
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1.RecyclerView内部已经强制使用VIewHolder,优化了对Item中View的复用。
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2.提供了一个较为灵活的布局管理类,LayoutManager,用来控制RecyclerView是线性展示还是垂直展示,以及可以设置成瀑布流。并且提供了ItemDecoration这个类,来灵活的让用户来设置分割线。
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3.用ItemAnimator可以对item进行布局的删减动画效果。
设置布局管理器:
1、竖向listview
rv.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));
2、横向listview
rv.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
3、竖向gridView
rv.setLayoutManager(new GridLayoutManager(this, 5));
4、横向gridview
rv.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.WRAP_CONTENT)); rv.setLayoutManager(new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.HORIZONTAL));
5、瀑布流
rv.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT)); rv.setLayoutManager(new StaggeredGridLayoutManager(5, StaggeredGridLayoutManager.VERTICAL));
需在adapter随机设置高度
rvAdapter.setType(3);
private int type = 0; public RvAdapter(Context context, List<Integer> datas) { this.context = context; this.datas = datas; for (int i : datas) { int height = (int) (Math.random() * 100 + 300); heights.add(height); } } public void setType(int type) { this.type = type; }
@Override public void onBindViewHolder(MyViewHolder holder, final int position) { RecyclerView.LayoutParams layoutParams; if (type == 0) { layoutParams = new RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT); } else if (type == 1) { layoutParams = new RecyclerView.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT); } else { layoutParams = new RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, heights.get(position)); layoutParams.setMargins(2, 2, 2, 2); }
设置Item增加、移除动画:
rv.setItemAnimator(new DefaultItemAnimator());
实现添加分割线:
(默认分割线类):
public class DividerGridItemDecoration extends RecyclerView.ItemDecoration { private static final int[] ATTRS = new int[]{android.R.attr.listDivider}; private Drawable mDivider; public DividerGridItemDecoration(Context context) { final TypedArray a = context.obtainStyledAttributes(ATTRS); mDivider = a.getDrawable(0); a.recycle(); } @Override public void onDraw(Canvas c, RecyclerView parent, State state) { drawHorizontal(c, parent); drawVertical(c, parent); } private int getSpanCount(RecyclerView parent) { // 列数 int spanCount = -1; LayoutManager layoutManager = parent.getLayoutManager(); if (layoutManager instanceof GridLayoutManager) { spanCount = ((GridLayoutManager) layoutManager).getSpanCount(); } else if (layoutManager instanceof StaggeredGridLayoutManager) { spanCount = ((StaggeredGridLayoutManager) layoutManager) .getSpanCount(); } return spanCount; } public void drawHorizontal(Canvas c, RecyclerView parent) { int childCount = parent.getChildCount(); for (int i = 0; i < childCount; i++) { final View child = parent.getChildAt(i); final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child .getLayoutParams(); final int left = child.getLeft() - params.leftMargin; final int right = child.getRight() + params.rightMargin + mDivider.getIntrinsicWidth(); final int top = child.getBottom() + params.bottomMargin; final int bottom = top + mDivider.getIntrinsicHeight(); mDivider.setBounds(left, top, right, bottom); mDivider.draw(c); } } public void drawVertical(Canvas c, RecyclerView parent) { final int childCount = parent.getChildCount(); for (int i = 0; i < childCount; i++) { final View child = parent.getChildAt(i); final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child .getLayoutParams(); final int top = child.getTop() - params.topMargin; final int bottom = child.getBottom() + params.bottomMargin; final int left = child.getRight() + params.rightMargin; final int right = left + mDivider.getIntrinsicWidth(); mDivider.setBounds(left, top, right, bottom); mDivider.draw(c); } } private boolean isLastColum(RecyclerView parent, int pos, int spanCount, int childCount) { LayoutManager layoutManager = parent.getLayoutManager(); if (layoutManager instanceof GridLayoutManager) { if ((pos + 1) % spanCount == 0)// 如果是最后一列,则不需要绘制右边 { return true; } } else if (layoutManager instanceof StaggeredGridLayoutManager) { int orientation = ((StaggeredGridLayoutManager) layoutManager) .getOrientation(); if (orientation == StaggeredGridLayoutManager.VERTICAL) { if ((pos + 1) % spanCount == 0)// 如果是最后一列,则不需要绘制右边 { return true; } } else { childCount = childCount - childCount % spanCount; if (pos >= childCount)// 如果是最后一列,则不需要绘制右边 return true; } } return false; } private boolean isLastRaw(RecyclerView parent, int pos, int spanCount, int childCount) { LayoutManager layoutManager = parent.getLayoutManager(); if (layoutManager instanceof GridLayoutManager) { childCount = childCount - childCount % spanCount; if (pos >= childCount)// 如果是最后一行,则不需要绘制底部 return true; } else if (layoutManager instanceof StaggeredGridLayoutManager) { int orientation = ((StaggeredGridLayoutManager) layoutManager) .getOrientation(); // StaggeredGridLayoutManager 且纵向滚动 if (orientation == StaggeredGridLayoutManager.VERTICAL) { childCount = childCount - childCount % spanCount; // 如果是最后一行,则不需要绘制底部 if (pos >= childCount) return true; } else // StaggeredGridLayoutManager 且横向滚动 { // 如果是最后一行,则不需要绘制底部 if ((pos + 1) % spanCount == 0) { return true; } } } return false; } @Override public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) { int spanCount = getSpanCount(parent); int childCount = parent.getAdapter().getItemCount(); if (isLastRaw(parent, itemPosition, spanCount, childCount))// 如果是最后一行,则不需要绘制底部 { outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0); } else if (isLastColum(parent, itemPosition, spanCount, childCount))// 如果是最后一列,则不需要绘制右边 { outRect.set(0, 0, 0, mDivider.getIntrinsicHeight()); } else { outRect.set(0, 0, mDivider.getIntrinsicWidth(), mDivider.getIntrinsicHeight()); } } }
1、固定工具类:
public class DividerItemDecoration extends RecyclerView.ItemDecoration { private static final int[] ATTRS = new int[]{android.R.attr.listDivider}; public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL; public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL; private Drawable mDivider; private int mOrientation; public DividerItemDecoration(Context context, int orientation) { final TypedArray a = context.obtainStyledAttributes(ATTRS); mDivider = a.getDrawable(0); a.recycle(); setOrientation(orientation); } public void setOrientation(int orientation) { if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) { throw new IllegalArgumentException("invalid orientation"); } mOrientation = orientation; } @Override public void onDraw(Canvas c, RecyclerView parent) { Log.v("recyclerview - itemdecoration", "onDraw()"); if (mOrientation == VERTICAL_LIST) { drawVertical(c, parent); } else { drawHorizontal(c, parent); } } public void drawVertical(Canvas c, RecyclerView parent) { final int left = parent.getPaddingLeft(); final int right = parent.getWidth() - parent.getPaddingRight(); final int childCount = parent.getChildCount(); for (int i = 0; i < childCount; i++) { final View child = parent.getChildAt(i); RecyclerView v = new RecyclerView( parent.getContext()); final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child .getLayoutParams(); final int top = child.getBottom() + params.bottomMargin; final int bottom = top + mDivider.getIntrinsicHeight(); mDivider.setBounds(left, top, right, bottom); mDivider.draw(c); } } public void drawHorizontal(Canvas c, RecyclerView parent) { final int top = parent.getPaddingTop(); final int bottom = parent.getHeight() - parent.getPaddingBottom(); final int childCount = parent.getChildCount(); for (int i = 0; i < childCount; i++) { final View child = parent.getChildAt(i); final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child .getLayoutParams(); final int left = child.getRight() + params.rightMargin; final int right = left + mDivider.getIntrinsicHeight(); mDivider.setBounds(left, top, right, bottom); mDivider.draw(c); } } @Override public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) { if (mOrientation == VERTICAL_LIST) { outRect.set(0, 0, 0, mDivider.getIntrinsicHeight()); } else { outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0); } } }
2、分割线drawable divider.xml文件:
<?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" > <solid android:color="@color/colorPrimary"/> <size android:height="10dp" android:width="1dp"/> </shape> <!-- 渐变色分割线--> <!--<?xml version="1.0" encoding="utf-8"?>--> <!--<shape xmlns:android="http://schemas.android.com/apk/res/android"--> <!--android:shape="rectangle" >--> <!--<gradient--> <!--android:centerColor="#ff00ff00"--> <!--android:endColor="#ff0000ff"--> <!--android:startColor="#ffff0000"--> <!--android:type="linear" />--> <!--<size android:height="4dp"/>--> <!--</shape>--> 3、divider.xml在AppTheme中引用:
<resources> <!-- Base application theme. --> <style name="AppTheme" parent="Theme.AppCompat"> <!-- Customize your theme here. --> <item name="colorPrimary">@color/colorPrimary</item> <item name="colorPrimaryDark">@color/colorPrimaryDark</item> <item name="colorAccent">@color/colorAccent</item> <item name="android:listDivider">@drawable/divider</item> </style> </resources>
4、recycleview设置分割线:
private RecyclerView.ItemDecoration itemDecoration;
itemDecoration = new DividerItemDecoration(this, DividerItemDecoration.VERTICAL_LIST); //默认分割线 itemDecoration = new DividerGridItemDecoration(this); rv.addItemDecoration(itemDecoration);
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