WPF分页写法（MVVM实现）

TODO：萌新劝退，以下正文（举例，具体参照代码）

1. 新建一个基类，实现双向通知（绑定）

2. public class PropertyChangedBase : INotifyPropertyChanged
       {
           public event PropertyChangedEventHandler PropertyChanged;
           protected void NotifyPropertyChanged([CallerMemberName]string propertyName = null)
           {
               PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
           }
           protected bool SetProperty(ref T backingStore, T value, [CallerMemberName]string propertyName = "", Action onChanged = null)
           {
               if (EqualityComparer.Default.Equals(backingStore, value))
                   return false;
   
               backingStore = value;
               onChanged?.Invoke();
               NotifyPropertyChanged(propertyName);
               return true;
           }
       }

    

3. 建立SSviewModel继承PropertyChangedBase

4. public class SSViewModel : PropertyChangedBase
   {
           /// 
   
           /// 历史数据列表（选中的设备）
           /// 
           public ObservableCollection CheckHisDataList { get; set; }
   
           private int selectHisCurrentIndex;
           /// 
   
           /// 页码变更事件
           /// 
           public int SelectHisCurrentIndex
           {
               get => selectHisCurrentIndex; set => SetProperty(ref selectHisCurrentIndex, value, "", () =>
               {
                   GetHisData(SelectHisStartTime, SelectHisEndTime, selectHisCurrentIndex, SelectHisInterval, SelectHisStandard);
               });
           }
           
           /// 
   
           /// 获取历史数据函数
           /// 委托（将函数委托） 以方便在SSviewModel中调用
           /// 
           public Action GetHisData { get; set; }
   }
   

   TODO：逻辑实现

5.   //Todo：以下业务实现
   
           /// 
   
           /// 全局变量
           /// 
           SSViewModel sSView = null;
   
           /// 
   
           /// 获取服务器数据
           /// 
           /// 开始时间
           /// 结束时间
           /// 页码
           /// 间隔
           /// 只显示超标 默认false
           private async void GetHisData(DateTime start, DateTime end, int page, int interval, bool standard)
           {
               #region 判断是否跨月，并是否支持跨月查询
               if (start > end)
               {
                   MessageBoxX.Show("开始时间不能大于结束时间。", "警 告", MessageBoxIcon.Warning);
                   return;
               }
               var handler = PendingBoxX.Show("加载服务器数据，请稍等（1/2）...", "Processing", false, Application.Current.MainWindow);
               await Task.Run(() =>
               {
                   #region 业务执行
                   var authenticationHeaderValue = new AuthenticationHeaderValue("bearer", CacheExt.GetCache("AccessToken"));
                   _client.DefaultRequestHeaders.Authorization = authenticationHeaderValue;
                   List> param = new List>();
                   param.Add(new KeyValuePair("tabName", $"datalog{start.ToString("yyyyMM")}"));
                   var res = Client.Post("/api/system/GetCanRequest", _client, new FormUrlEncodedContent(param));
                   if (int.Parse(res["data"].ToString()) != 1)
                   {
                       //不支持跨月。判断时间是否跨月
                       if (start.Month != end.Month && start.Year != end.Year)
                       {
                           MessageBoxX.Show("当前用户不支持跨月查询", "警 告", MessageBoxIcon.Warning);
                           return;
                       }
                       else
                       {
                           param = new List>();
                           param.Add(new KeyValuePair("tabName", $"datalog{start.ToString("yyyyMM")}"));
                           param.Add(new KeyValuePair("deviceNo", $"{sSView.SelectedDeviceNo.ToString()}"));
                           param.Add(new KeyValuePair("startTime", $"{start.ToString("yyyy-MM-dd HH:mm:ss")}"));
                           param.Add(new KeyValuePair("endTime", $"{end.ToString("yyyy-MM-dd HH:mm:ss")}"));
                           param.Add(new KeyValuePair("interVal", $"{interval}"));
                           param.Add(new KeyValuePair("standArd", $"{standard}"));
                           var hisList = Client.Post("/api/data/PostHisDataList", _client, new FormUrlEncodedContent(param));
                           curveList.Clear();
                           curveList = hisList.HisDatas;
                           curveCount = hisList.HisDataCount;
                           if (hisList.HisDatas.Any())
                               SetList(hisList.HisDatas, hisList.HisDataCount, page);
                           else
                           {
                               MessageBoxX.Show("没有数据或查询失败", "警 告", MessageBoxIcon.Warning);
                               return;
                           }
                       }
                   }
                   else
                   {
                       //直接请求数据
                       param = new List>();
                       param.Add(new KeyValuePair("tabName", $"datalog{start.ToString("yyyyMM")}"));
                       param.Add(new KeyValuePair("deviceNo", $"{sSView.SelectedDeviceNo.ToString()}"));
                       param.Add(new KeyValuePair("startTime", $"{start.ToString("yyyy-MM-dd HH:mm:ss")}"));
                       param.Add(new KeyValuePair("endTime", $"{end.ToString("yyyy-MM-dd HH:mm:ss")}"));
                       param.Add(new KeyValuePair("interVal", $"{interval}"));
                       param.Add(new KeyValuePair("standArd", $"{standard}"));
                       var hisList = Client.Post("/api/data/PostHisDataList", _client, new FormUrlEncodedContent(param));
                       curveList.Clear();
                       curveList = hisList.HisDatas;
                       curveCount = hisList.HisDataCount;
                       if (hisList.HisDatas.Any())
                           SetList(hisList.HisDatas, hisList.HisDataCount, page);
                       else
                       {
                           MessageBoxX.Show("没有数据或查询失败", "警 告", MessageBoxIcon.Warning);
                           return;
                       }
                   }
                   #endregion
               });
               handler.UpdateMessage("正在完成，后续数据即将推送（2/2）。");
               handler.Close();
               #endregion
           }
   
         //TODO:调用了SetList函数（此处函数更新UI）
   
           /// 
   
           /// 设置数据列表
           /// 
           /// 
           /// 
           private ObservableCollection SetList(List hisDatas, HisDataCount count, int page)
           {
               #region 统计
               sSView.CheckHiss = new SSViewModel.CheckHis()
               {
                   HisCount = count.Counts.ToString(),
                   HisTemp = $"{(count.MaxTemp / 10.0).ToString("f1")} / {(count.MinTemp / 10.0).ToString("f1")}",
                   HisHumi = $"{(count.MaxHumi / 10.0).ToString("f1")} / {(count.MinHumi / 10.0).ToString("f1")}",
                   HisAvg = $"{(count.AvgTemp / 10.0).ToString("f1")} / {(count.AvgHumi / 10.0).ToString("f1")}"
               };
               //总页数
               sSView.SelectHisTotalIndex = (hisDatas.Count + 500 - 1) / 500;
               #endregion
               hisDatas = hisDatas.Skip((page - 1) * 500).Take(500).ToList();
               //清空
               Dispatcher.Invoke(() =>
               {
                   sSView.CheckHisDataList.Clear();
               });
               foreach (var item in hisDatas)
               {
                   SSViewModel.CheckHisData viewModel = new SSViewModel.CheckHisData()
                   {
                       Deviceno = item.DeviceNO,
                       DataTime = item.DataTime.ToString("yyyy-MM-dd HH:mm:ss"),
                       Humi = item.Humidity / 10.0,
                       Temp = item.Temperature / 10.0,
                       Standard = item.alarmstatus == 1 ? "超标" : ""
                   };
                   Dispatcher.Invoke(() =>
                   {
                       sSView.CheckHisDataList.Add(viewModel);
                   });
               }
               return sSView.CheckHisDataList;
           }
   
   
         //在此页面构造函数中将函数委托给SSviewModel
         sSView.GetHisData = GetHisData;  //此处

   思路逻辑如下：

6. 要通过MVVM实现分页，关键在页码变更的时候通知后台变更数据
7. 页码变更事件在SSviewModel里面，我们不能跨页面调用函数。所以此处用到了委托
8. 实现效果图