05_微信小程序之scroll-view下拉刷新以及上拉加载

05_微信小程序之scroll-view下拉刷新以及上拉加载

一.布局确定

由于在微信小程序中,每一个xml节点会被自动加上page标签,而page标签默认是高度自适应,并且可以滑动的,所以为保证滑动不会冲突,在使用scroll-view时需要将page的宽高设置为100%,并且禁用page默认的滑动效果

page {
  width: 100%;
  height: 100%;
  overflow: hidden;
}

接下来只需要在xml文件中使用scroll-view,并将scroll-view的’scroll-y’属性设为true,scroll-view才具备垂直滚动的条件,当然如果您希望scroll-view横向滑动,那么只需要将scroll-view的’scroll-x’属性设为true即可。

注意:如果要求scroll-view纵向滑动,那么除了将’scroll-y’属性设为true之外,还需要保证scroll-view的高度是确定的,横向滑动也是同样的道理,需要保证scroll-view的宽度是确定的。

由于前面已经将page的高度确定为100%;只需要将scroll-view的高度设置为100%,scroll-view的高度也就被确定为屏幕的高度了,此时,当scroll-view中所有字节点的高度超出屏幕高度,scroll-view就可以滑动了。

page {
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.scroll-view {
  width: 100%;
  height: 100%;
}

<!--index.wxml-->
<scroll-view class="scroll-view" scroll-y="{{true}}">
  <!-- 此处省略n多个<view>wqwqwqw</view>节点 -->
</scroll-view>

二.将scroll-view设置为可下拉

只需将scroll-view的’refresher-enabled’属性设为true,即可实现下拉效果

<!--index.wxml-->
<scroll-view class="scroll-view" scroll-y="{{true}}" refresher-enabled="{{true}}">
  <!-- 此处省略n多个<view>wqwqwqw</view>节点 -->
</scroll-view>

三.处理下拉刷新的逻辑

这里先模拟下从pc分页请求数据的过程,一般情况下,我们向pc请求一个列表数据时,会向pc传递一个pageSize和start参数,告诉pc端每一页要给我多少条数据,并且我请求的是第几页的数据,pc在返回列表数据时,会把相应的列表数据返给我们,并通过totalCount告诉我们总共会有多少条数据。开始模拟吧!

  data: {
    list:[],
    serverDatas: [],
    pageSize: 20,
    totalPage: 1,
    start: 1
  },

  onLoad: async function(options) {
    var serverDatas = new Array();
    for(var i=0; i<101; i++) {
      serverDatas.push((i+1) + "")
    }
    this.setData({
      serverDatas: serverDatas
    })

    var list = await this.getList(1, 20)
    console.log(list)
    var list = await this.getList(2, 20)
    console.log(list)
    var list = await this.getList(3, 20)
    console.log(list)
    var list = await this.getList(4, 20)
    console.log(list)
    var list = await this.getList(5, 20)
    console.log(list)
    var list = await this.getList(6, 20)
    console.log(list)
  },

  getList: function(start, pageSize) {
    var serverDatas = this.data.serverDatas
    var totalCount = serverDatas.length

    var list = new Array()
    var length = start * pageSize >= serverDatas.length ? serverDatas.length : start * pageSize
    for(var i=(start - 1) * pageSize; i<length; i++) {
      list.push((i + 1) + "")
    }

    var result = {
      totalCount: totalCount,
      list: list
    }
    return new Promise(function (resolve, reject) {
      //模拟网络请求的耗时操作
      setTimeout(function () {
        resolve(result);
      }, 3000);
    });
  }

网络请求的过程已经模拟完了,万事已具备,只欠逻辑实现了????

bindrefresherrefresh ==> loading设为true,调用接口,结束后loading设为false
最后将loading的值绑定给refresher-triggered属性即可

  data: {
    list:[],
    serverDatas: [],
    pageSize: 20,
    totalPage: 1,
    start: 1,
    loading: false
  },

  onLoad: async function(options) {
    var serverDatas = new Array();
    for(var i=0; i<101; i++) {
      serverDatas.push((i+1) + "")
    }
    this.setData({
      serverDatas: serverDatas
    })

    this.setData({
      loading: true
    })
  },

  getList: function(start, pageSize) {
    var serverDatas = this.data.serverDatas
    var totalCount = serverDatas.length

    var list = new Array()
    var length = start * pageSize >= serverDatas.length ? serverDatas.length : start * pageSize
    for(var i=(start - 1) * pageSize; i<length; i++) {
      list.push((i + 1) + "")
    }

    var result = {
      totalCount: totalCount,
      list: list
    }
    return new Promise(function (resolve, reject) {
      //模拟网络请求的耗时操作
      var timer = setTimeout(function () {
        resolve(result);
        clearTimeout(timer)
      }, 3000);
    });
  },

  refreshDatas: async function() {
    var pageSize = this.data.pageSize
    this.setData({
      loading:true
    })
    var result = await this.getList(1, pageSize)
    var list = result.list
    var totalCount = result.totalCount

    //计算总页数
    var totalPage = 1
    if (totalCount % pageSize > 0) {
      totalPage = Math.floor(totalCount / pageSize) + 1
    } else {
      totalPage = totalCount / pageSize
    }

    this.setData({
      loading: false,
      list: list,
      totalPage: totalPage
    })
  },

  onRefresh: function(e) {
    this.refreshDatas()
  }

四.处理上拉加载更多数据的逻辑

bindrefresherrefresh => 请求下一页的数据,并追加到list中

<scroll-view class="scroll-view" scroll-y="{{true}}" refresher-enabled="{{true}}" bindrefresherrefresh="onRefresh" refresher-triggered="{{loading}}" bindscrolltolower="onReachBottom">
  <view class="list">
    <view wx:for="{{list}}">item{{item}}</view>
  </view>
</scroll-view>

/**index.wxss**/
page {
  width: 100%;
  height: 100%;
  overflow: none;
}

.scroll-view {
  width: 100%;
  height: 100%;
}

.list {
  width: 100%;
  //保证scroll-view中的子元素不能充满屏幕时,也能触发上拉加载
  height: calc(100vh + 10rpx);
}

  data: {
    list:[],
    serverDatas: [],
    pageSize: 20,
    totalPage: 1,
    start: 1,
    loading: false
  },

  onLoad: async function(options) {
    var serverDatas = new Array();
    for(var i=0; i<101; i++) {
      serverDatas.push((i+1) + "")
    }
    this.setData({
      serverDatas: serverDatas
    })

    this.setData({
      loading: true
    })
  },

  getList: function(start, pageSize) {
    var serverDatas = this.data.serverDatas
    var totalCount = serverDatas.length

    var list = new Array()
    var length = start * pageSize >= serverDatas.length ? serverDatas.length : start * pageSize
    for(var i=(start - 1) * pageSize; i<length; i++) {
      list.push((i + 1) + "")
    }

    var result = {
      totalCount: totalCount,
      list: list
    }
    return new Promise(function (resolve, reject) {
      //模拟网络请求的耗时操作
      var timer = setTimeout(function () {
        resolve(result);
        clearTimeout(timer)
      }, 3000);
    });
  },

  refreshDatas: async function() {
    var pageSize = this.data.pageSize
    this.setData({
      loading:true
    })
    var result = await this.getList(1, pageSize)
    var list = result.list
    var totalCount = result.totalCount

    //计算总页数
    var totalPage = 1
    if (totalCount % pageSize > 0) {
      totalPage = Math.floor(totalCount / pageSize) + 1
    } else {
      totalPage = totalCount / pageSize
    }

    this.setData({
      loading: false,
      list: list,
      totalPage: totalPage,
      start: 1
    })
  },

  onRefresh: function(e) {
    this.refreshDatas()
  },

  onReachBottom: function(e) {
    var that = this
    var timer = setTimeout(function() {
      that.loadDatas()
      clearTimeout(timer)
    }, 500)
  },

  loadDatas: async function() {
    var pageSize = this.data.pageSize
    var that = this
    var start = that.data.start
    var totalPage = that.data.totalPage

    start += 1

    if (start > totalPage) {
      return
    }

    wx.showLoading({
      title: '加载中',
    })
    var result = await this.getList(start, pageSize)
    var newList = result.list
    var totalCount = result.totalCount

    //计算总页数
    var totalPage = 1
    if (totalCount % pageSize > 0) {
      totalPage = Math.floor(totalCount / pageSize) + 1
    } else {
      totalPage = totalCount / pageSize
    }

    //追加数据
    var list = this.data.list
    for (var i = 0; i < newList.length; i++) {
      list.push(newList[i])
    }

    wx.hideLoading()

    this.setData({
      list: list,
      totalPage: totalPage,
      start: start
    })
  }