gridview分页

protected void lnkbtnFrist_Click(object sender, EventArgs e)
    {
        //首页
        this.GridView_username.PageIndex = ;
        this.ReadData();
    }
    protected void lnkbtnPre_Click(object sender, EventArgs e)
    {
        //上一页
        if (this.GridView_username.PageIndex > )
        {
            this.GridView_username.PageIndex = this.GridView_username.PageIndex - ;
            this.ReadData();
        }
    }
    protected void lnkbtnNext_Click(object sender, EventArgs e)
    {
        //下一页
        if (this.GridView_username.PageIndex < this.GridView_username.PageCount)
        {
            this.GridView_username.PageIndex = this.GridView_username.PageIndex + ;
            this.ReadData();
        }
    }
    protected void lnkbtnLast_Click(object sender, EventArgs e)
    {
        //最后一页
        this.GridView_username.PageIndex = this.GridView_username.PageCount;
        this.ReadData();
    }
    //选择所需要的页数
    protected void ddlCurrentPage_SelectedIndexChanged(object sender, EventArgs e)
    {
        this.GridView_username.PageIndex = this.ddlCurrentPage.SelectedIndex;
        this.ReadData();
    }