本文转自;http://blog.csdn.net/michael_ouyang/article/details/56846185

loadmore

加载更多（分页加载）

当用户打开一个页面时，假设后台数据量庞大时，一次性地返回所有数据给客户端，页面的打开速度就会有所下降，而且用户只看上面的内容而不需要看后面的内容时，也浪费用户流量，基于优化的角度来考虑，后台不要一次性返回所有数据，当用户有需要再往下翻的时候，再加载更加数据出来。

业务需求：

列表滚动到底部时，继续往上拉，加载更多内容

必备参数：

（1）pageindex: 1 //第几次加载

（2）callbackcount: 15 //需要返回数据的个数

其他参数：

根据接口的所需参数

实现原理：

当第一次访问接口时，传递2个必备参数（第1次加载，需要返回数据的个数为15个），和其他参数（需要搜索的字符串）给后台，后台返回第一次数据过来。在请求成功的的回调函数中，判断返回的数据是否>0，是，则取出数据，渲染视图层，并把“上拉加载”显示在列表底部；否，则没有数据可取，并把“没有更多”显示在列表底部，同时把“上拉加载”隐藏掉。

当用户已经滚动到列表底部（这里使用到小程序提供的scroll-view组件的bindscrolltolower事件），触发bindscrolltolower事件，参数pageindex+1，再把2个必备参数（第2次加载，需要返回数据的个数为15个）和其他参数（需要搜索的字符串）给后台，后台把其余的数据返回给前台，前台在原来数据的基础上添加数据。

示例：

wxml:

<view class="search">
<view class="search-bar">
<view class="search-wrap">
<icon type="search" size="16" class="icon-search" />
<input type="text" placeholder="请输入搜索内容" class="search-input" name="searchKeyword" bindinput="bindKeywordInput" value="{{searchKeyword}}" />
</view>
<view class="search-cancel" bindtap="keywordSearch">搜索</view>
</view>
<view class="search-result">
<scroll-view scroll-y="true" bindscrolltolower="searchScrollLower">
<view class="result-item" wx:for="{{searchSongList}}" wx:key="unique" data-data="{{item}}" >
<view class="icon{{item.isonly=='0' ? ' nocopyright' : ''}}"></view>
<text class="title">{{item.songname}}</text>
<view class="subtitle">
<text wx:for="{{item.singer}}" wx:key="unique">{{item.name}}</text>
</view>
</view>
<view class="loading" hidden="{{!searchLoading}}">正在载入更多...</view>
<view class="loading complete" hidden="{{!searchLoadingComplete}}">已加载全部</view>
</scroll-view>
</view>
</view>

<view class="search">

  <view class="search-bar">

    <view class="search-wrap">

        <icon type="search" size="16" class="icon-search" />

        <input type="text" placeholder="请输入搜索内容" class="search-input" name="searchKeyword" bindinput="bindKeywordInput" value="{{searchKeyword}}" />

    </view>

    <view class="search-cancel" bindtap="keywordSearch">搜索</view>

  </view>

  <view class="search-result">

    <scroll-view scroll-y="true" bindscrolltolower="searchScrollLower">

      <view class="result-item" wx:for="{{searchSongList}}" wx:key="unique"  data-data="{{item}}" >

        <view class="icon{{item.isonly=='0' ? ' nocopyright' : ''}}"></view>

        <text class="title">{{item.songname}}</text>

        <view class="subtitle">

          <text wx:for="{{item.singer}}" wx:key="unique">{{item.name}}</text>

        </view>

      </view>

      <view class="loading" hidden="{{!searchLoading}}">正在载入更多...</view>

      <view class="loading complete" hidden="{{!searchLoadingComplete}}">已加载全部</view>

    </scroll-view>

  </view>

</view>

js:

var util = require('../../utils/util.js')
Page({
data: {
searchKeyword: '', //需要搜索的字符
searchSongList: [], //放置返回数据的数组
isFromSearch: true, // 用于判断searchSongList数组是不是空数组，默认true，空的数组
searchPageNum: 1, // 设置加载的第几次，默认是第一次
callbackcount: 15, //返回数据的个数
searchLoading: false, //"上拉加载"的变量，默认false，隐藏
searchLoadingComplete: false //“没有数据”的变量，默认false，隐藏
},
//输入框事件，每输入一个字符，就会触发一次
bindKeywordInput: function(e){
console.log("输入框事件")
this.setData({
searchKeyword: e.detail.value
})
},
//搜索，访问网络
fetchSearchList: function(){
let that = this;
let searchKeyword = that.data.searchKeyword,//输入框字符串作为参数
searchPageNum = that.data.searchPageNum,//把第几次加载次数作为参数
callbackcount =that.data.callbackcount; //返回数据的个数
//访问网络
util.getSearchMusic(searchKeyword, searchPageNum,callbackcount, function(data){
console.log(data)
//判断是否有数据，有则取数据
if(data.data.song.curnum != 0){
let searchList = [];
//如果isFromSearch是true从data中取出数据，否则先从原来的数据继续添加
that.data.isFromSearch ? searchList=data.data.song.list : searchList=that.data.searchSongList.concat(data.data.song.list)
that.setData({
searchSongList: searchList, //获取数据数组
zhida: data.data.zhida, //存放歌手属性的对象
searchLoading: true //把"上拉加载"的变量设为false，显示
});
//没有数据了，把“没有数据”显示，把“上拉加载”隐藏
}else{
that.setData({
searchLoadingComplete: true, //把“没有数据”设为true，显示
searchLoading: false //把"上拉加载"的变量设为false，隐藏
});
}
})
},
//点击搜索按钮，触发事件
keywordSearch: function(e){
this.setData({
searchPageNum: 1, //第一次加载，设置1
searchSongList:[], //放置返回数据的数组,设为空
isFromSearch: true, //第一次加载，设置true
searchLoading: true, //把"上拉加载"的变量设为true，显示
searchLoadingComplete:false //把“没有数据”设为false，隐藏
})
this.fetchSearchList();
},
//滚动到底部触发事件
searchScrollLower: function(){
let that = this;
if(that.data.searchLoading && !that.data.searchLoadingComplete){
that.setData({
searchPageNum: that.data.searchPageNum+1, //每次触发上拉事件，把searchPageNum+1
isFromSearch: false //触发到上拉事件，把isFromSearch设为为false
});
that.fetchSearchList();
}
}
})

var util = require('../../utils/util.js')

Page({

  data: {

    searchKeyword: '',  //需要搜索的字符

    searchSongList: [], //放置返回数据的数组

    isFromSearch: true,   // 用于判断searchSongList数组是不是空数组，默认true，空的数组

    searchPageNum: 1,   // 设置加载的第几次，默认是第一次

    callbackcount: 15,      //返回数据的个数

    searchLoading: false, //"上拉加载"的变量，默认false，隐藏

    searchLoadingComplete: false  //“没有数据”的变量，默认false，隐藏

  },

  //输入框事件，每输入一个字符，就会触发一次

  bindKeywordInput: function(e){

    console.log("输入框事件")

    this.setData({

      searchKeyword: e.detail.value

    })

  },

  //搜索，访问网络

  fetchSearchList: function(){

    let that = this;

    let searchKeyword = that.data.searchKeyword,//输入框字符串作为参数

        searchPageNum = that.data.searchPageNum,//把第几次加载次数作为参数

        callbackcount =that.data.callbackcount; //返回数据的个数

    //访问网络

    util.getSearchMusic(searchKeyword, searchPageNum,callbackcount, function(data){

      console.log(data)

      //判断是否有数据，有则取数据

      if(data.data.song.curnum != 0){

        let searchList = [];

        //如果isFromSearch是true从data中取出数据，否则先从原来的数据继续添加

        that.data.isFromSearch ? searchList=data.data.song.list : searchList=that.data.searchSongList.concat(data.data.song.list)

        that.setData({

          searchSongList: searchList, //获取数据数组

          zhida: data.data.zhida, //存放歌手属性的对象

          searchLoading: true   //把"上拉加载"的变量设为false，显示

        });

      //没有数据了，把“没有数据”显示，把“上拉加载”隐藏

      }else{

        that.setData({

          searchLoadingComplete: true, //把“没有数据”设为true，显示

          searchLoading: false  //把"上拉加载"的变量设为false，隐藏

        });

      }

    })

  },

  //点击搜索按钮，触发事件

  keywordSearch: function(e){

    this.setData({

      searchPageNum: 1,   //第一次加载，设置1

      searchSongList:[],  //放置返回数据的数组,设为空

      isFromSearch: true,  //第一次加载，设置true

      searchLoading: true,  //把"上拉加载"的变量设为true，显示

      searchLoadingComplete:false //把“没有数据”设为false，隐藏

    })

    this.fetchSearchList();

  },

  //滚动到底部触发事件

  searchScrollLower: function(){

    let that = this;

    if(that.data.searchLoading && !that.data.searchLoadingComplete){

      that.setData({

        searchPageNum: that.data.searchPageNum+1,  //每次触发上拉事件，把searchPageNum+1

        isFromSearch: false  //触发到上拉事件，把isFromSearch设为为false

      });

      that.fetchSearchList();

    }

  }

})

util.js:

function getSearchMusic(keyword, pageindex, callbackcount, callback){
wx.request({
url: 'https://c.y.qq.com/soso/fcgi-bin/search_for_qq_cp',
data: {
g_tk: 5381,
uin: 0,
format: 'json',
inCharset: 'utf-8',
outCharset: 'utf-8',
notice: 0,
platform: 'h5',
needNewCode: 1,
w: keyword,
zhidaqu: 1,
catZhida: 1,
t: 0,
flag: 1,
ie: 'utf-8',
sem: 1,
aggr: 0,
perpage: 20,
n: callbackcount, //返回数据的个数
p: pageindex,
remoteplace: 'txt.mqq.all',
_: Date.now()
},
method: 'GET',
header: {'content-Type': 'application/json'},
success: function(res){
if(res.statusCode == 200){
callback(res.data);
}
}
})
}
module.exports = {
getSearchMusic: getSearchMusic
}

function getSearchMusic(keyword, pageindex, callbackcount, callback){

  wx.request({

    url: 'https://c.y.qq.com/soso/fcgi-bin/search_for_qq_cp',

    data: {

      g_tk: 5381,

      uin: 0,

      format: 'json',

      inCharset: 'utf-8',

      outCharset: 'utf-8',

      notice: 0,

      platform: 'h5',

      needNewCode: 1,

      w: keyword,

      zhidaqu: 1,

      catZhida: 1,

      t: 0,

      flag: 1,

      ie: 'utf-8',

      sem: 1,

      aggr: 0,

      perpage: 20,

      n: callbackcount,  //返回数据的个数

      p: pageindex,

      remoteplace: 'txt.mqq.all',

      _: Date.now()

    },

    method: 'GET',

    header: {'content-Type': 'application/json'},

    success: function(res){

      if(res.statusCode == 200){

        callback(res.data);

      }

    }

  })

}

module.exports = {

  getSearchMusic: getSearchMusic

}

wxss:

page{
display: flex;
flex-direction: column;
height: 100%;
}
/*搜索*/
.search{
flex: auto;
display: flex;
flex-direction: column;
background: #fff;
}
.search-bar{
flex: none;
display: flex;
align-items: center;
justify-content: space-between;
padding: 20rpx;
background: #f4f4f4;
}
.search-wrap{
position: relative;
flex: auto;
display: flex;
align-items: center;
height: 80rpx;
padding: 0 20rpx;
background: #fff;
border-radius: 6rpx;
}
.search-wrap .icon-search{
margin-right: 10rpx;
}
.search-wrap .search-input{
flex: auto;
font-size: 28rpx;
}
.search-cancel{
padding: 0 20rpx;
font-size: 28rpx;
}
/*搜索结果*/
.search-result{
flex: auto;
position: relative;
}
.search-result scroll-view{
position: absolute;
bottom: 0;
left: 0;
right: 0;
top: 0;
}
.result-item{
position: relative;
display: flex;
flex-direction: column;
padding: 20rpx 0 20rpx 110rpx;
overflow: hidden;
border-bottom: 2rpx solid #e5e5e5;
}
.result-item .media{
position: absolute;
left: 16rpx;
top: 16rpx;
width: 80rpx;
height: 80rpx;
border-radius: 999rpx;
}
.result-item .title,
.result-item .subtitle{
overflow: hidden;
text-overflow: ellipsis;
white-space: nowrap;
line-height: 36rpx;
}
.result-item .title{
margin-bottom: 4rpx;
color: #000;
}
.result-item .subtitle{
color: #808080;
font-size: 24rpx;
}
.result-item:first-child .subtitle text{
margin-right: 20rpx;
}
.result-item:not(:first-child) .subtitle text:not(:first-child):before{
content: '/';
margin: 0 8rpx;
}
.loading{
padding: 10rpx;
text-align: center;
}
.loading:before{
display: inline-block;
margin-right: 5rpx;
vertical-align: middle;
content: '';
width: 40rpx;
height: 40rpx;
background: url(../../images/icon-loading.png) no-repeat;
background-size: contain;
animation: rotate 1s linear infinite;
}
.loading.complete:before{
display: none;
}

page{

  display: flex;

  flex-direction: column;

  height: 100%;

}

/*搜索*/

.search{

  flex: auto;

  display: flex;

  flex-direction: column;

  background: #fff;

}

.search-bar{

  flex: none;

  display: flex;

  align-items: center;

  justify-content: space-between;

  padding: 20rpx;

  background: #f4f4f4;

}

.search-wrap{

  position: relative;

  flex: auto;

  display: flex;

  align-items: center;

  height: 80rpx;

  padding: 0 20rpx;

  background: #fff;

  border-radius: 6rpx;

}

.search-wrap .icon-search{

  margin-right: 10rpx;

}

.search-wrap .search-input{

  flex: auto;

  font-size: 28rpx;

}

.search-cancel{

  padding: 0 20rpx;

  font-size: 28rpx;

}

/*搜索结果*/

.search-result{

  flex: auto;

  position: relative;

}

.search-result scroll-view{

  position: absolute;

  bottom: 0;

  left: 0;

  right: 0;

  top: 0;

}

.result-item{

  position: relative;

  display: flex;

  flex-direction: column;

  padding: 20rpx 0 20rpx 110rpx;

  overflow: hidden;

  border-bottom: 2rpx solid #e5e5e5;

}

.result-item .media{

  position: absolute;

  left: 16rpx;

  top: 16rpx;

  width: 80rpx;

  height: 80rpx;

  border-radius: 999rpx;

}

.result-item .title,

.result-item .subtitle{

  overflow: hidden;

  text-overflow: ellipsis;

  white-space: nowrap;

  line-height: 36rpx;

}

.result-item .title{

  margin-bottom: 4rpx;

  color: #000;

}

.result-item .subtitle{

  color: #808080;

  font-size: 24rpx;

}

.result-item:first-child .subtitle text{

  margin-right: 20rpx;

}

.result-item:not(:first-child) .subtitle text:not(:first-child):before{

  content: '/';

  margin: 0 8rpx;

}

.loading{

  padding: 10rpx;

  text-align: center;

}

.loading:before{

  display: inline-block;

  margin-right: 5rpx;

  vertical-align: middle;

  content: '';

  width: 40rpx;

  height: 40rpx;

  background: url(../../images/icon-loading.png) no-repeat;

  background-size: contain;

  animation: rotate 1s linear infinite;

}

.loading.complete:before{

  display: none;

}