RecyclerView的使用、res下新建菜单menu-main.xml

1.参考链接：Android RecyclerView 使用完全解析 体验艺术般的控件

2.使用RecyclerView需要导入support v7包：

在build.gradle(app)中设置：(和AndroidStudio设置的一样就行了，哈哈)

compile 'com.android.support:recyclerview-v7:25.1.0'

3.疑问：瀑布流中添加分割线操作？

4.代码如下：

MainActivity:

package com.ruru.recyclerview;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.Menu;
import android.view.MenuItem;

import com.ruru.recyclerview.adapter.DividerGridItemDecoration;
import com.ruru.recyclerview.adapter.DividerItemDecoration;
import com.ruru.recyclerview.adapter.MyAdapter;

import java.util.ArrayList;
import java.util.List;

/**
* RecycleView-回收与复用View 高度解耦 给予充分定制自由
*/
public class MainActivity extends AppCompatActivity {
//打印log语句
public static final String TAG = "info";
//UI控件
private RecyclerView recycleView;
//ListView集合
private List<String> list;
private MyAdapter mAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//初始化控件
initView();
//初始化list集合
initData();
//初始化布局
initLayout();
}

/**
* 初始化RecycleView的布局
*/
private void initLayout() {
/*设置布局
RecyclerView.LayoutManager是一个抽象类 系统实现了三个实现类
LinearLayoutManager 现行管理器，支持横向、纵向。
GridLayoutManager 网格布局管理器
StaggeredGridLayoutManager 瀑布就式布局管理器*/

//ListView
//        recycleView.setLayoutManager(new LinearLayoutManager(this));
//        recycleView.setAdapter(new MyAdapter(this, list));
//当我们调用recycleView.addItemDecoration()方法添加decoration的时候，RecycleView在绘制的时候，
// 会去绘制decorator,即调用该类的onDraw()和onDrawOver()方法
//        recycleView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL_LIST));

//GridView
//        recycleView.setLayoutManager(new GridLayoutManager(this,4));
//        recycleView.setAdapter(new MyAdapter(this, list));
//        recycleView.addItemDecoration(new DividerGridItemDecoration(this));

// 瀑布流StaggeredGridLayoutManager
// 第二个参数传一个orientation，
// 如果传入的是StaggeredGridLayoutManager.VERTICAL代表有多少列；注：固定列上下混动
// 如果传入的是StaggeredGridLayoutManager.HORIZONTAL就代表有多少行；注:固定行的话可能会左右滑动
//如果是横向的时候，item的宽度需要注意去设置，毕竟横向的宽度没有约束了，应为控件可以横向滚动了
recycleView.setLayoutManager(new StaggeredGridLayoutManager(4, StaggeredGridLayoutManager.VERTICAL));
mAdapter = new MyAdapter(this, list);
recycleView.setAdapter(mAdapter);

// 设置item动画
recycleView.setItemAnimator(new DefaultItemAnimator());
}

/**
* 初始化list集合数据
*/
private void initData() {
list = new ArrayList<String>();
for (int i = 1; i < 10; i++) {
list.add("序号" + i);
}
}

/**
* 初始化控件
*/
private void initView() {
recycleView = (RecyclerView) findViewById(R.id.recycleView);
}

/**
* Activity中点击MenuItem触发
* 注意，这里更新数据集不是用adapter.notifyDataSetChanged()
* 而是notifyItemInserted(position)与notifyItemRemoved(position)
*/
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
getMenuInflater().inflate(R.menu.main, menu);
return super.onCreateOptionsMenu(menu);
}

/**
* Activity中点击MenuItem触发
*/
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.id_action_add:
mAdapter.addData(1);
break;
case R.id.id_action_delete:
mAdapter.removeData(1);
break;
}
return true;
}
}

MyAdapter:

package com.ruru.recyclerview.adapter;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.ruru.recyclerview.R;
import java.util.List;

/**
* Created by SophieLiang on 2017/2/28.
*/
//注意要加后面的<MyAdapter.MyViewHolder>
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {

private Context context;
private List<String> list;

public MyAdapter(Context context, List<String> list) {
this.context = context;
this.list = list;
}

@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
MyViewHolder holder = new MyViewHolder(LayoutInflater.from(context).inflate(R.layout.item, parent, false));
return holder;
}

@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
holder.tv_name.setText(list.get(position));
//如果是瀑布流的话，为item设计个随机的高度
}

@Override
public int getItemCount() {
return list.size();
}

class MyViewHolder extends RecyclerView.ViewHolder {

TextView tv_name;//不要写成private static

public MyViewHolder(View itemView) {
super(itemView);
tv_name = (TextView) itemView.findViewById(R.id.tv_name);
}
}

/**
* 添加动画更新数据集
*/
public void addData(int position) {
list.add(position, "Insert One");
notifyItemInserted(position);
}

/**
* 删除动画更新数据集
*/
public void removeData(int position) {
list.remove(position);
notifyItemRemoved(position);
}
}

ItemDecoration:

package com.ruru.recyclerview;

import android.graphics.Canvas;
import android.graphics.Rect;
import android.support.v7.widget.RecyclerView;
import android.view.View;

/**
* Created by SophieLiang on 2017/2/28.
*/
public abstract class ItemDecoration {

//onDraw方法先于drawChildren
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
onDraw(c, parent, state);
}

//onDrawOver在drawChildren之后，一般我们选择复写其中一个即可。
public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
onDrawOver(c, parent, state);
}

public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
getItemOffsets(outRect, ((RecyclerView.LayoutParams) view.getLayoutParams()).getViewLayoutPosition(),
parent);
}

//getItemOffsets 可以通过outRect.set()为每个Item设置一定的偏移量，主要用于绘制Decorator。
@Deprecated
public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
outRect.set(0, 0, 0, 0);
}
}

DividerItemDecoration:ListView添加分割线的操作

/**
* Created by SophieLiang on 2017/2/28.
* 添加分割线操作
*/
public class DividerItemDecoration extends RecyclerView.ItemDecoration {
private static final String TAG = "info";

/**
* 通过读取系统主题中的 Android.R.attr.listDivider作为Item间的分割线,并且支持横向和纵向
*/
private static final int[] ATTRS = new int[]{
android.R.attr.listDivider
};

//定义了两个方法中的orientation
public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;

public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;

//获取到listDivider以后，该属性的值是个Drawable
private Drawable mDivider;

private int mOrientation;

public DividerItemDecoration(Context context, int orientation) {
//自定义属性
final TypedArray a = context.obtainStyledAttributes(ATTRS);
mDivider = a.getDrawable(0);
a.recycle();
//设置分割线的方向
setOrientation(orientation);
}

/**
* 设置分割线方向
*/
public void setOrien
da66
tation(int orientation) {
if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
throw new IllegalArgumentException("invalid orientation");
}
mOrientation = orientation;
}

/**
* 画分割线:一个item只有一个children
*/
@Override
public void onDraw(Canvas c, RecyclerView parent) {
Log.i(TAG, "onDraw:+++ ");
if (mOrientation == VERTICAL_LIST) {
drawVertical(c, parent);
} else {
drawHorizontal(c, parent);
}
}

/**
* 画垂直分割线
*/
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);
android.support.v7.widget.RecyclerView v = new android.support.v7.widget.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);//左上右下
mDivider.draw(c);
}
}

/**
* 画水平分割线
*/
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);
}
}

/**
* 在getItemOffsets中，outRect去设置了绘制的范围。onDraw中实现了真正的绘制
*/
@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);
}
}
}

DividerGridItemDecoration: GridView添加分割线的操作

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, RecyclerView.State state) {

drawHorizontal(c, parent);
drawVertical(c, parent);

}

private int getSpanCount(RecyclerView parent) {
// 列数
int spanCount = -1;
RecyclerView.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) {
RecyclerView.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) {
RecyclerView.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;
}

/**
* 主要在getItemOffsets方法中，去判断如果是最后一行，则不需要绘制底部；如果是最后一列，则不需要绘制右边，
* 整个判断也考虑到了StaggeredGridLayoutManager的横向和纵向
* 一般如果仅仅是希望有空隙，还是去设置item的margin方便
*/
@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());
}
}
}

divider_bg.xml:设置分割线的背景颜色

<?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>

res右键第二个新建menu目录，再新建xml文件：main.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:id="@+id/id_action_add"
android:title="添加动画"/>
<item
android:id="@+id/id_action_delete"
android:title="删除动画"/>
</menu>

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.ruru.recyclerview.MainActivity">

<!--RecycleView中divider这样的属性不会起作用-->
<android.support.v7.widget.RecyclerView
android:id="@+id/recycleView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:divider="#ffff0000"
android:dividerHeight="10dp"></android.support.v7.widget.RecyclerView>

</RelativeLayout>

item.xml:ListView有一个item,GridView有好多个ChildView

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="#44ff0000">

<TextView
android:id="@+id/tv_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="center" />
</FrameLayout>