Repeater和GridView支持DataPager分页做法

时间：2022-06-25 03:07:14 编辑：袖梨来源：一聚教程网

改造办法是自己写一个控件，让它继承GridView或Repeater，并实现IPageableItemContainer 接口。下面要发的是国外某高手写的代码，测试有效。具体使用的时候，要建一个类库项目，把代码编译成dll后，就可以添加到VS的工具箱里了！

一、自定义Repeater

代码如下

复制代码

using System.Web.UI;
using System.Web.UI.WebControls;

namespace WYJ.Web.Controls
{
///

/// Repeater with support for DataPager
///

[ToolboxData("{0}:DataPagerRepeater>")]
public class DataPagerRepeater : Repeater, System.Web.UI.WebControls.IPageableItemContainer, INamingContainer
{
///

/// Number of rows to show
///

public int MaximumRows { get { return ViewState["MaximumRows"] != null ? (int)ViewState["MaximumRows"] : -1; } }

///

/// First row to show
///

public int StartRowIndex { get { return ViewState["StartRowIndex"] != null ? (int)ViewState["StartRowIndex"] : -1; } }

///

/// Total rows. When PagingInDataSource is set to true you must get the total records from the datasource (without paging) at the FetchingData event
/// When PagingInDataSource is set to true you also need to set this when you load the data the first time.
///

public int TotalRows { get { return ViewState["TotalRows"] != null ? (int)ViewState["TotalRows"] : -1; } set { ViewState["TotalRows"] = value; } }

///

/// If repeater should store data source in view state. If false you need to get and bind data at post back. When using a connected data source this is handled by the data source.
///

public bool PersistentDataSource
{
get { return ViewState["PersistentDataSource"] != null ? (bool)ViewState["PersistentDataSource"] : true; }
set { ViewState["PersistentDataSource"] = value; }
}
///

/// Set to true if you want to handle paging in the data source.
/// Ex if you are selecting data from the database and only select the current rows
/// you must set this property to true and get and rebind data at the FetchingData event.
/// If this is true you must also set the TotalRecords property at the FetchingData event.
///

///
///
public bool PagingInDataSource
{
get { return ViewState["PageingInDataSource"] != null ? (bool)ViewState["PageingInDataSource"] : false; }
set { ViewState["PageingInDataSource"] = value; }
}
///

/// Checks if you need to rebind data source at postback
///

public bool NeedsDataSource
{
get
{
if (PagingInDataSource)
return true;
if (IsBoundUsingDataSourceID == false && !Page.IsPostBack)
return true;
if (IsBoundUsingDataSourceID == false && PersistentDataSource == false && Page.IsPostBack)
return true;
else
return false;
}
}

///

/// Loading ViewState
///

///
protected override void LoadViewState(object savedState)
{
base.LoadViewState(savedState);

//if (Page.IsPostBack)
//{

// if (!IsBoundUsingDataSourceID && PersistentDataSource && ViewState["DataSource"] != null)
// {
// this.DataSource = ViewState["DataSource"];
// this.DataBind(true);
// }
// if (IsBoundUsingDataSourceID)
// {
// this.DataBind();
// }
//}
}

protected override void OnLoad(System.EventArgs e)
{
if (Page.IsPostBack)
{
if (NeedsDataSource && FetchingData != null)
{
if (PagingInDataSource)
{
SetPageProperties(StartRowIndex, MaximumRows, true);
}
FetchingData(this, null);
}

if (!IsBoundUsingDataSourceID && PersistentDataSource && ViewState["DataSource"] != null)
{
this.DataSource = ViewState["DataSource"];
this.DataBind();
}
if (IsBoundUsingDataSourceID)
{
this.DataBind();
}

}

base.OnLoad(e);

}

///

/// Method used by pager to set totalrecords
///

/// startRowIndex
/// maximumRows
/// databind
public void SetPageProperties(int startRowIndex, int maximumRows, bool databind)
{
ViewState["StartRowIndex"] = startRowIndex;
ViewState["MaximumRows"] = maximumRows;

if (TotalRows > -1)
{
if (TotalRowCountAvailable != null)
{
TotalRowCountAvailable(this, new PageEventArgs((int)ViewState["StartRowIndex"], (int)ViewState["MaximumRows"], TotalRows));
}
}
}
///

/// OnDataPropertyChanged
///

protected override void OnDataPropertyChanged()
{
if (MaximumRows != -1 || IsBoundUsingDataSourceID)
{
this.RequiresDataBinding = true;

}

base.OnDataPropertyChanged();
}

///

/// Renders only current items selected by pager
///

///
protected override void RenderChildren(HtmlTextWriter writer)
{
if (!PagingInDataSource && MaximumRows != -1)
{
foreach (RepeaterItem item in this.Items)
{
if (item.ItemType == ListItemType.Item || item.ItemType == ListItemType.AlternatingItem)
{
item.Visible = false;
if (item.ItemIndex >= (int)ViewState["StartRowIndex"] && item.ItemIndex {
item.Visible = true;
}
}
else
{
item.Visible = true;
}
}
}
base.RenderChildren(writer);
}

///

/// Get Data
///

///
protected override System.Collections.IEnumerable GetData()
{
System.Collections.IEnumerable dataObjects = base.GetData();

if (dataObjects == null && this.DataSource != null)
{
if (this.DataSource is System.Collections.IEnumerable)
dataObjects = (System.Collections.IEnumerable)this.DataSource;
else
dataObjects = ((System.ComponentModel.IListSource)this.DataSource).GetList();
}

if (!PagingInDataSource && MaximumRows != -1 && dataObjects != null)
{
int i = -1;

if (dataObjects != null)
{
i = 0;
foreach (object o in dataObjects)
{
i++;
}

}

ViewState["TotalRows"] = i;

if (!IsBoundUsingDataSourceID && PersistentDataSource)
ViewState["DataSource"] = this.DataSource;

SetPageProperties(StartRowIndex, MaximumRows, true);

}

if (PagingInDataSource && !Page.IsPostBack)
{
SetPageProperties(StartRowIndex, MaximumRows, true);
}

return dataObjects;
}

///

/// Event when pager/repeater have counted total rows
///

public event System.EventHandler TotalRowCountAvailable;

///

/// Event when repeater gets the data on postback
///

public event System.EventHandler FetchingData;

}

ASPX页面要做的事情（以我网站的留言板为例）：

首先得把标签注册进来

代码如下	复制代码

然后添加我们的Repeater

代码如下

复制代码

name="">

之后添加.NET自带的DataPager，并自定义一些分页样式

代码如下

复制代码

后台代码：

分页部分不需要代码。下面发的代码是切换每页显示数量的：

代码如下

复制代码

protected void lnkbtn10_Click(object sender, EventArgs e)
{
DataPager1.PageSize = 10;
lnkbtn10.CssClass = "currentpagesize";
lnkbtn20.CssClass = "";
lnkbtn30.CssClass = "";
}

protected void lnkbtn20_Click(object sender, EventArgs e)
{
DataPager1.PageSize = 20;
lnkbtn20.CssClass = "currentpagesize";
lnkbtn10.CssClass = "";
lnkbtn30.CssClass = "";
}

protected void lnkbtn30_Click(object sender, EventArgs e)
{
DataPager1.PageSize = 30;
lnkbtn30.CssClass = "currentpagesize";
lnkbtn10.CssClass = "";
lnkbtn20.CssClass = "";
}

二、自定义GridView

代码如下

复制代码

using System;
using System.Collections;
using System.Web.UI.WebControls;

namespace WYJ.Web.Controls
{
///

/// DataPagerGridView is a custom control that implements GrieView and IPageableItemContainer
///

public class DataPagerGridView : GridView, IPageableItemContainer
{
public DataPagerGridView()
: base()
{
PagerSettings.Visible = false;
}

///

/// TotalRowCountAvailable event key
///

private static readonly object EventTotalRowCountAvailable = new object();

///

/// Call base control's CreateChildControls method and determine the number of rows in the source
/// then fire off the event with the derived data and then we return the original result.
///

///
///
///
protected override int CreateChildControls(IEnumerable dataSource, bool dataBinding)
{
int rows = base.CreateChildControls(dataSource, dataBinding);

// if the paging feature is enabled, determine the total number of rows in the datasource
if (this.AllowPaging)
{
// if we are databinding, use the number of rows that were created, otherwise cast the datasource to an Collection and use that as the count
int totalRowCount = dataBinding ? rows : ((ICollection)dataSource).Count;

// raise the row count available event
IPageableItemContainer pageableItemContainer = this as IPageableItemContainer;
this.OnTotalRowCountAvailable(new PageEventArgs(pageableItemContainer.StartRowIndex, pageableItemContainer.MaximumRows, totalRowCount));

// make sure the top and bottom pager rows are not visible
if (this.TopPagerRow != null)
this.TopPagerRow.Visible = false;

if (this.BottomPagerRow != null)
this.BottomPagerRow.Visible = false;
}
return rows;
}

///

/// Set the control with appropriate parameters and bind to right chunk of data.
///

///
///
///
void IPageableItemContainer.SetPageProperties(int startRowIndex, int maximumRows, bool databind)
{
int newPageIndex = (startRowIndex / maximumRows);
this.PageSize = maximumRows;

if (this.PageIndex != newPageIndex)
{
bool isCanceled = false;
if (databind)
{
// create the event arguments and raise the event
GridViewPageEventArgs args = new GridViewPageEventArgs(newPageIndex);
this.OnPageIndexChanging(args);

isCanceled = args.Cancel;
newPageIndex = args.NewPageIndex;
}

// if the event wasn't cancelled change the paging values
if (!isCanceled)
{
this.PageIndex = newPageIndex;

if (databind)
this.OnPageIndexChanged(EventArgs.Empty);
}
if (databind)
this.RequiresDataBinding = true;
}
}

///

/// IPageableItemContainer's StartRowIndex = PageSize * PageIndex properties
///

int IPageableItemContainer.StartRowIndex
{
get { return this.PageSize * this.PageIndex; }
}

///

/// IPageableItemContainer's MaximumRows = PageSize property
///

int IPageableItemContainer.MaximumRows
{
get { return this.PageSize; }
}

///

///
///

event EventHandler IPageableItemContainer.TotalRowCountAvailable
{
add { base.Events.AddHandler(DataPagerGridView.EventTotalRowCountAvailable, value); }
remove { base.Events.RemoveHandler(DataPagerGridView.EventTotalRowCountAvailable, value); }
}

///

///
///

///
protected virtual void OnTotalRowCountAvailable(PageEventArgs e)
{
EventHandler handler = (EventHandler)base.Events[DataPagerGridView.EventTotalRowCountAvailable];
if (handler != null)
{
handler(this, e);
}
}
}
}

用法与Repeater类似，不多发了～

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Repeater和GridView支持DataPager分页做法

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