public class ValuesController : ApiController { // GET api/values [HttpGet] public List Get(int page,int count) { using (Models.School_TestEntities entites = new Models.School_TestEntities()) { var date= entites.ContextTable.OrderBy(c => c.ID).Skip((page - 1) * count).Take(count).ToList(); return date; } } // PUT api/values/5public bool UpdateDate(Models.ContextTable datemodel) { // var date = JsonConvert.DeserializeObject(value);using (Models.School_TestEntities entites = new Models.School_TestEntities()) { var model = entites.ContextTable.Where(a => a.ID == datemodel.ID).FirstOrDefault(); model.Title = datemodel.Title; model.AddTime = datemodel.AddTime; model.Context = datemodel.Context; if (entites.SaveChanges() > 0) { return true; } return false; } } public bool AddDate(Models.ContextTable model) { var date = model; using (Models.School_TestEntities entites = new Models.School_TestEntities()) { entites.ContextTable.Add(date); if (entites.SaveChanges() >0) { return true; } } return false; } // DELETE api/values/5public bool Delete(int id) { using (Models.School_TestEntities entites = new Models.School_TestEntities()) { var date = entites.ContextTable.Where(a => a.ID == id).FirstOrDefault(); entites.ContextTable.Remove(date); if (entites.SaveChanges() > 0) { return true; } return false; } } }
3.編寫服務倉儲
就是編寫一個訪問WebAPI用的倉儲.代碼如下:
public class ContextDataStore { HttpClient client; string RestUrl = "http://192.168.3.74:53470/api/values"; public ContextDataStore() { client = new HttpClient(); client.MaxResponseContentBufferSize = 256000; } public async Task AddItemAsync(ContextModel item) { var uri = new Uri(RestUrl+ "/AddDate/"); var json = JsonConvert.SerializeObject(item);var content = new StringContent(json); content.Headers.ContentType = new MediaTypeHeaderValue("application/json"); var response = await client.PostAsync(uri, content); if (response.IsSuccessStatusCode) { var date = await response.Content.ReadAsStringAsync(); return Convert.ToBoolean(date); } return false; } public async Task UpdateItemAsync(ContextModel item) { var uri = new Uri(RestUrl + "/UpdateDate/"); var json = JsonConvert.SerializeObject(item);var content = new StringContent(json); content.Headers.ContentType = new MediaTypeHeaderValue("application/json"); var response = await client.PostAsync(uri, content); if (response.IsSuccessStatusCode) { var date = await response.Content.ReadAsStringAsync(); return Convert.ToBoolean(date); } return false; } public async Task DeleteItemAsync(int id) { var uri = new Uri(string.Format(RestUrl + "/Delete/?id=" + id, string.Empty)); var response = await client.DeleteAsync(uri); if (response.IsSuccessStatusCode) { var content = await response.Content.ReadAsStringAsync(); return Convert.ToBoolean(content); } return false; } public async Task> GetItemsAsync(int page,int rows) { var uri = new Uri(string.Format(RestUrl+"/Get/?page="+page+ "&count=" + rows, string.Empty)); var response = await client.GetAsync(uri); List Items = new List(); if (response.IsSuccessStatusCode) { var content = await response.Content.ReadAsStringAsync(); try { Items = JsonConvert.DeserializeObject>(content); } catch (Exception ex) { } } return Items; } }
4.編寫ViewModel來與介面進行綁定交互
詳解請查看系列目錄中的MVVM篇
代碼如下(注釋中有解釋):
public class ContextViewModel: INotifyPropertyChanged { //初始化倉儲public ContextDataStore DataStore =new ContextDataStore(); //設置綁定對象public ObservableCollection Items { get; set; } //設置刷新命令public Command LoadItemsCommand { get; set; } public event PropertyChangedEventHandler PropertyChanged; private int page = 1; private int rows = 10; /// /// 初始化各種資料與監聽 /// public ContextViewModel() { Items = new ObservableCollection(); LoadItemsCommand = new Command(async () => await ExecuteLoadItemsCommand()); //監聽添加的消息MessagingCenter.Subscribe(this, "AddItem", async (obj, item) => { var _item = item as ContextModel; var date = await DataStore.AddItemAsync(_item); if (date) { LoadDate(); await obj.DisplayAlert("提示", "添加成功!", "關閉"); await obj.Navigation.PopAsync(); } else { await obj.DisplayAlert("提示", "添加失敗!", "關閉"); } }); //監聽更新的消息MessagingCenter.Subscribe(this, "UpdateItem", async (obj, item) => { var date = await DataStore.UpdateItemAsync(item); if (date) { LoadDate(); await obj.DisplayAlert("提示", "修改成功!", "關閉"); await obj.Navigation.PopAsync(); } else { await obj.DisplayAlert("提示", "修改失敗!", "關閉"); } }); ExecuteLoadItemsCommand(); } /// /// 刪除的方法 /// /// /// public async Task DeleteItem(int id) { var date = await DataStore.DeleteItemAsync(id); if (date) { var item = Items.Where(a => a.ID == id).FirstOrDefault(); Items.Remove(item); OnPropertyChanged("Items"); } return date; } /// /// 載入資料的命令 /// /// async Task ExecuteLoadItemsCommand() { try { //Items.Clear();var items = await DataStore.GetItemsAsync(page,rows); foreach (var item in items) { Items.Add(item); } OnPropertyChanged("Items"); page++; } catch (Exception ex) { } } /// /// 重新刷新資料 /// private async void LoadDate() { Items.Clear(); page = 1; var items = await DataStore.GetItemsAsync(page, rows); foreach (var item in items) { Items.Add(item); } OnPropertyChanged("Items"); page++; } protected virtual void OnPropertyChanged(string propertyName) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } }
