Android开发上滑悬停且头部可刷新

需求：上滑列表后推荐，小岛，专题置顶，可左右切换。因为头部有重要内容，所有头部出现且滑到顶之后，再下来可刷新头部内容

效果图：

实现思路：

首先上滑悬停想到的是协调布局CoordinatorLayout，
第二用刷新控件包裹着协调布局，我用的刷新控件是refreshlayout.RefreshLayout
第三在代码中app_bar_layout.addOnOffsetChangedListener判断刷新布局什么时候可用，什么时候不可用

下面是实现文档

步骤一：布局

步骤二：使用示例

class OutRefreshActivity : AppCompatActivity() {

private var context: Context? = null

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_out_refresh)
    context = this

    setRefreshLayout(mRefreshLayout)
    common_recycler.layoutManager = LinearLayoutManager(context)
    val headView = LayoutInflater.from(context).inflate(R.layout.layout_out_refresh_head, common_recycler, false)
    val headAdapter = OutRefreshHeadAdapter()
    common_recycler?.adapter = headAdapter
    headAdapter.addHeaderView(headView)
    //关键,什么时候RefreshLayout可用
    app_bar_layout.addOnOffsetChangedListener(object :AppBarLayout.OnOffsetChangedListener{
        override fun onOffsetChanged(p0: AppBarLayout?, verticalOffset: Int) {
            mRefreshLayout.isEnabled = verticalOffset >=0
            //只能下拉
            mRefreshLayout?.direction = RefreshLayoutDirection.TOP
        }

    })

    val fragments: MutableList = ArrayList()
    fragments.add(AFragment())
    fragments.add(BFragment())
    fragments.add(CFragment())
    val titles: MutableList = ArrayList()
    titles.add("推荐")
    titles.add("小岛")
    titles.add("专题")
    val baseFragmentAdapter = BaseFragmentAdapter(supportFragmentManager, fragments, titles)
    vp_pager_ceo_data.setAdapter(baseFragmentAdapter)
    stl_ceo_data.setViewPager(vp_pager_ceo_data)

}

protected fun setRefreshLayout(refreshLayout: RefreshLayout) {

    refreshLayout.direction = RefreshLayoutDirection.BOTH
    refreshLayout.setColorSchemeResources(R.color.m_red_two, R.color.m_charcoal_grey, R.color.m_purple, R.color.m_green, R.color.m_blue)
    refreshLayout.setOnRefreshListener(object : RefreshLayout.OnRefreshListener {
        override fun onPullDownToRefresh() {
            //做刷新操作，模拟请求接口
            Handler().postDelayed(object :Runnable{
                override fun run() {
                    refreshLayout.isRefreshing = false //隐藏刷新圈圈
                }

            },1000)
        }

        override fun onPullUpToRefresh() {
            //加载更多
        }
    })
}
}

上面有OutRefreshHeadAdapter，BaseFragmentAdapter，AFragment没给出，就是普通的操作类，相信你们都会写或者项目中就有。
重点是上面的关键代码

app_bar_layout.addOnOffsetChangedListener(object :AppBarLayout.OnOffsetChangedListener{
        override fun onOffsetChanged(p0: AppBarLayout?, verticalOffset: Int) {
            mRefreshLayout.isEnabled = verticalOffset >=0
            //只能下拉
            mRefreshLayout?.direction = RefreshLayoutDirection.TOP
        }

    })

ok,这样的效果就做好了。
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