/// <summary>
 /// 清除所有数据
 /// </summary>
 /// <returns></returns>
 public Task <int> ClearAllData()
 {
     return(LocalDatabaseHelper <SearchedItem> .ClearDatabase());
 }
 /// <summary>
 /// 查找所有搜索历史
 /// </summary>
 /// <returns></returns>
 public Task <List <SearchedItem> > GetAllSearchedItem()
 {
     return(LocalDatabaseHelper <SearchedItem> .GetAllItems());
 }
 /// <summary>
 /// 删除所有搜索历史
 /// </summary>
 /// <returns></returns>
 public Task <int> DeleteAllSearchedItem()
 {
     return(LocalDatabaseHelper <SearchedItem> .DeleteAllItems());
 }
 /// <summary>
 /// 插入搜索历史
 /// </summary>
 /// <param name="searchedItem"></param>
 /// <returns></returns>
 public Task <int> InsertSearchedItem(SearchedItem searchedItem)
 {
     //Database.DeleteAllAsync<SearchedItem>();   //先清空
     return(LocalDatabaseHelper <SearchedItem> .InsertOrReplaceAsync(searchedItem));
 }