页面无限跳转间如何保存页面状态 (3)

在页面上的使用，定义好了以上这些之后，在页面中该怎样用呢？

首先，在List页面中实现IPageInfo接口：

     public class RoleList : System.Web.UI.Page,IPageInfo

然后针对每一个DataGrid实例化一个DataInfo对象：

protected DataInfo dataInfo = new DataInfo("Role");

接着写一些处理DataGrid状态的代码，我是使用的属性：

#region 数据网格状态信息

         private System.Collections.Hashtable SearchParams

         {

              get

              {

                   if (ViewState["SearchParams"] != null)

                   {

                       return (Hashtable)ViewState["SearchParams"];

                   }

                   else

                       return null;

              }

              set

              {

                   ViewState["SearchParams"] = value;

              }

         }

 

         private System.Collections.Hashtable OtherDataParams

         {

              get

              {

                   if (ViewState["OtherDataParams"] != null)

                   {

                       return (Hashtable)ViewState["OtherDataParams"];

                   }

                   else

                       return null;

              }

              set

              {

                   ViewState["OtherDataParams"] = value;

              }

         }

 

         private int CurrentPage

         {

              get

              {

                   return MyDataGrid.CurrentPageIndex;

              }

              set

              {

                   MyDataGrid.CurrentPageIndex = value;

                   MyDataGrid.DataBind();

                   navigateRole.CurrentPage = MyDataGrid.CurrentPageIndex + 1;

                   navigateRole.TotalPages = MyDataGrid.PageCount;

              }

         }

 

         private string SortExpression

         {

              get

              {

                   return dsSystem.Role.DefaultView.Sort;

              }

              set

              {

                   dsSystem.Role.DefaultView.Sort = value;

                   MyDataGrid.DataBind();

                   navigateRole.TotalPages = MyDataGrid.PageCount;

              }

         }

 

         private string ItemID

         {

              get

              {

                   if (MyDataGrid.SelectedIndex >= 0)

                   {

                       return MyDataGrid.DataKeys[MyDataGrid.SelectedIndex].ToString();

                   }

                   else

                       return null;

              }

              set

              {

                   int pageIndex = MyDataGrid.CurrentPageIndex;

                   bool find = false;

                   for( int j = 0; j < MyDataGrid.PageCount && find == false; j++)

                   {

                       MyDataGrid.CurrentPageIndex = j;

                       MyDataGrid.DataBind();

                        for(int i = 0; i < MyDataGrid.Items.Count; i++)

                       {

                            if (MyDataGrid.DataKeys[i].ToString() == value)

                            {

                                 find = true;

                                 break;

                            }

                       }

                   }

                   if (find == false)

                   {

                       MyDataGrid.CurrentPageIndex = pageIndex;

                       MyDataGrid.DataBind();

                   }

                   navigateRole.CurrentPage = MyDataGrid.CurrentPageIndex + 1;

                   navigateRole.TotalPages = MyDataGrid.PageCount;

              }

         }

         #endregion

 

在PageLoad中取出前一页面的数据，进行处理，注意，从前一页面过来用的是Server.Transfer方法：

IPageInfo pageInfo = null;

                   //取出前一页面的信息并保存数据网格状态的信息

                   try

                   {

                       pageInfo = (IPageInfo)Context.Handler;

                   }

                   catch {}

                   if (pageInfo != null)

                   {

                       if (pageInfo.OtherParams != null)

                            OtherParams = pageInfo.OtherParams;

                       if (pageInfo.DataInfos != null)

                       {

                            //保存全部DataGrid信息

                            DataInfos = pageInfo.DataInfos;

                            //取出当前DataGrid的信息

                            if (pageInfo.DataInfos[dataInfo.DataName] != null)

                            {

                                 dataInfo = pageInfo.DataInfos[dataInfo.DataName];

                            }

                       }

              }

把数据取出来了然后自然就是处理了，我是设置前面那些属性的值的，实际上方法有很多种，这里就不详述了。

IPageInfo的实现，其中处理DataInfos属性时要更新页面上每一个DataGrid对应的DataInfo的信息，以反映最近的更改：

public string PageName

         {

              get

              {

                   return "RoleList";

              }

         }

 

         public Hashtable OtherParams

         {

              get

              {

                   if (ViewState["OtherParams"] != null)

                   {

                       return (Hashtable)ViewState["OtherParams"];

                   }

                   else

                       return null;

              }

              set

              {

                   ViewState["OtherParams"] = value;

              }

         }

 

         public DataInfoList DataInfos

         {

              get

              {

                   //更新数据网格状态信息

                   DataInfoList dataInfoList;

                   if (ViewState["DataInfos"] != null)

                       dataInfoList = (DataInfoList)ViewState["DataInfos"];

                   else

                       dataInfoList = new DataInfoList();

                   dataInfo.CurrentPage = CurrentPage;

                   dataInfo.ItemID = ItemID;

                   dataInfo.OtherParams = OtherDataParams;

                  dataInfo.SearchParams = SearchParams;

                   dataInfo.SortExpression = SortExpression;

                   dataInfoList[dataInfo.DataName] = dataInfo;

                   return dataInfoList;

              }

              set

              {

                   ViewState["DataInfos"] = value;

              }

         }

 

跳转到其他页面（如详细页面）：

Server.Transfer("RoleDetail.aspx");

 

对于Detail页面，会比较简单一些，因为基本上没有DatInfo更新的问题，旨在删除和新增时需要修改ItemID：

也是先实现接口：

public class RoleDetail : System.Web.UI.Page,IPageInfo

接着定义两个变量，一个保存前页来的数据，一个定义当前的数据类别，也就是要对哪一个DataInfo实例进行操作：

protected IPageInfo pageInfo;

protected string dataName = "Role";

 

PageLoad取出前页数据并处理当前项数据：

try

         {

              pageInfo = (IPageInfo)Context.Handler;

         }

         catch

         {

         }

         //取出当前项的ID

         if (pageInfo != null && pageInfo.DataInfos != null)

         {

              DataInfos = pageInfo.DataInfos;

         }

         //取详细数据

         if (DataInfos != null && DataInfos[dataName].ItemID != null)

              GetItemData();

         else

          GetNullData();

 

接口的实现：

public string PageName

         {

              get

              {

                   return "RoleDetail";

              }

         }

 

         public DataInfoList DataInfos

         {

              get

              {

                   if (ViewState["DataInfos"] != null)

                   {

                       return (DataInfoList)ViewState["DataInfos"];

                   }

                   else

                       return null;

              }

              set

              {

                   ViewState["DataInfos"] = value;

              }

         }

 

         public Hashtable OtherParams

         {

              get

              {

                   if (ViewState["OtherParams"] != null)

                   {

                       return (Hashtable)ViewState["OtherParams"];

                   }

                   else

                       return null;

              }

              set

              {

                   ViewState["OtherParams"] = value;

              }

         }

 

         #endregion

 

跳转到其他页面（如返回List）：

Server.Transfer("RoleList.aspx");

 

这样我们需要的功能便实现了。