RecyclerView进阶(1)

在之前用ListView的时候,如果ListView和ScrollView混着用的时候,就会产生滑动冲突,通常的解决措施是通过自定义ListView，重写其onMeasure,测量其高度让其不能滑动,然后就可以使用ScrollView的滑动了。

就像下边这样

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int expandSpec = MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE>>2,  MeasureSpec.AT_MOST);
super.onMeasure(widthMeasureSpec, expandSpec);
}

那么问题来了,在RecyclerView中你是否依然可以这么做呢,当然不能,我么知道,RecyclerView是一种高度解耦的空间,出了适配器之外,他有一个布局管理器LayoutManager来管理

对于LayoutManager,RecyclerView本身提供了三个实现类,分别为：

1：LinearLayoutManger 水平/横屏布局

实现ListView和HorizontalListView的效果

manager.setOrientation(LinearLayoutManager.HORIZONTAL);

manager.setOrientation(LinearLayoutManager.VERTICAL);

2：GridLayoutManger 网格布局

实现类似GridView一样的功能

mRecyclerView.setLayoutManager(new GridLayoutManager(this,4));
//设置一行4列

3：StagerGridLayoutManger 瀑布流布局

mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL));
//设置RecyclerView布局管理器为2列垂直排布

我们可以通过自定义布局管理器的方式来解决ScrollView和RecyclerView的滑动冲突

package com.longyue.recyclerviewdemo2;

import android.content.Context;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;

/**
* 计算适应高度
*/
public class CustomLinearLayoutManager extends LinearLayoutManager {

private int[] mMeasuredDimension = new int[2];

public CustomLinearLayoutManager(Context context) {
super(context);
}

public CustomLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
super(context, orientation, reverseLayout);
}

public CustomLinearLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}

@Override
public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state, int widthSpec, int heightSpec) {

final int widthMode = View.MeasureSpec.getMode(widthSpec);
final int heightMode = View.MeasureSpec.getMode(heightSpec);
final int widthSize = View.MeasureSpec.getSize(widthSpec);
final int heightSize = View.MeasureSpec.getSize(heightSpec);

int width = 0;
int height = 0;
for (int i = 0; i < getItemCount(); i++) {
measureScrapChild(recycler, i,
View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
mMeasuredDimension);

if (getOrientation() == HORIZONTAL) {
width = width + mMeasuredDimension[0];
if (i == 0) {
height = mMeasuredDimension[1];
}
} else {
height = height + mMeasuredDimension[1];
if (i == 0) {
width = mMeasuredDimension[0];
}
}
}
switch (widthMode) {
case View.MeasureSpec.EXACTLY:
width = widthSize;
case View.MeasureSpec.AT_MOST:
case View.MeasureSpec.UNSPECIFIED:
}

switch (heightMode) {
case View.MeasureSpec.EXACTLY:
height = heightSize;
case View.MeasureSpec.AT_MOST:
case View.MeasureSpec.UNSPECIFIED:
}

setMeasuredDimension(width,height);
}

private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
int heightSpec, int[] measuredDimension) {
try {
View view = recycler.getViewForPosition(0);//fix 动态添加时报IndexOutOfBoundsException

if (view != null) {
RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();

int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
getPaddingLeft() + getPaddingRight(), p.width);

int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
getPaddingTop() + getPaddingBottom(), p.height);

view.measure(childWidthSpec, childHeightSpec);
measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin;
recycler.recycleView(view);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
}
}
}

同时对ScrollView的事件分发时间进行处理onInterceptTouchEvent

package com.longyue.recyclerviewdemo2;

import android.content.Context;
import android.support.v4.widget.NestedScrollView;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.ViewConfiguration;

/**
* 自定义NestedScrollView
*/
public class CustomNestScrollView extends NestedScrollView{

private int downX;
private int downY;
private int mTouchSlop;

public CustomNestScrollView(Context context) {
super(context);
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
}

public CustomNestScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
}

public CustomNestScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
}

@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {

int action = ev.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
downX = (int) ev.getRawX();
downY = (int) ev.getRawY();
break;
case MotionEvent.ACTION_MOVE:
int moveY = (int) ev.getRawY();
if (Math.abs(moveY - downY) > mTouchSlop) {
return true;
}
}
return super.onInterceptTouchEvent(ev);
}
}

Demo下载