C#中常用的方法

1.绑定DropDownList下拉框数据。

        /// <summary>
        /// DropDownList绑定
        /// </summary>
        /// <param name="Drop">DropDownList的名称</param>
        /// <param name="dt">数据源 DataTable类型</param>
        /// <param name="TextField">绑定显示字段</param>
        /// <param name="ValueField">绑定隐藏字段</param>
        /// <param name="LastStrText">option显示字段</param>
        /// <param name="LastStrValue">option隐藏字段</param>
        public static void DropListBind(DropDownList Drop, DataTable dt, string TextField, string ValueField, string LastStrText, string LastStrValue)
        {
            BLL.t_JDKSB b_JDK = new LFMISPlat.BLL.t_JDKSB();
            Drop.DataSource = dt;
            Drop.DataTextField = TextField;
            Drop.DataValueField = ValueField;
            Drop.DataBind();
            if (LastStrText != "")
            {
                ListItem itemAll = new ListItem();
                itemAll.Text = LastStrText;
                itemAll.Value = LastStrValue;
                Drop.Items.Insert(0, itemAll);
            }
        }

当LastStrText为空字符串时，为标准绑定。有值的时候，将值追加到DropDownList最后一个Option中。

2.替换过多的文本为"......"来代替；

        /// <summary>
        /// 替换过多的文本为“。。。。。。”
        /// </summary>
        /// <returns></returns>
        public static String ReplaceSign(string str)
        {
            if (str.Length > 10)
            {
                return str.Replace(str.Substring(10, (str.Length - (10))), "........");
            }
            else
            {
                return str;
            }
        }

例如：string str="abcdefghijklmnop"; 替换后 str="abcdefghij......";

3.替换代表的数字为文字

        /// <summary>
        /// 替换数字为正常或者异常
        /// </summary>
        /// <param name="strStatus"></param>
        /// <returns></returns>

        public static string GetStrChangeValue(string strStatus)
        {
            string strValue = "";

            switch (strStatus)
            {
                case "0":
                    strValue = "<font size='2'>正常</font>";
                    break;
                case "1":
                    strValue = "<font color='red' size='2'>异常</font>";
                    break;
                default:
                    break;
            }
            return strValue;
        }

4.计算本年有多少天
       /// <summary>
        /// 计算当前年有多少天
        /// </summary>
        /// <returns></returns>
        public int DayOfYear()
        {
            DateTime firstDay = new DateTime(System.DateTime.Now.Year, 1, 1);
            DateTime lastDay = new DateTime(System.DateTime.Now.Year + 1, 1, 1);
            lastDay = lastDay.AddDays(-1);
            int dayofYear = Math.Abs(((TimeSpan)(lastDay - firstDay)).Days);
            return dayofYear;
        }

5.检查字符串，看有没有非法字符，不允许输入已|分割

#region 检查字符串，看有没有非法字符不允许输入已|分割

        /// <summary>
        /// 检查字符串，看有没有非发字符不允许输入已|分割
        /// </summary>
        /// <param name="str"></param>
        public static void check_str(string str)
        {
            string Illegal_Str = ",|&|+|'|\"|or|";
            string[] newstr = Illegal_Str.Split('|');
            for (int i = 0; i < (newstr.Length - 1); i++)
            {
                if (str.IndexOf(newstr[i]) != -1)
                {

System.Web.HttpContext.Current.Response.Write("<script>alert('含有非法字符！');history.back()</script>");

                }
            }
        }
        #endregion

一般是在登陆的时候，验证用户名或密码的时候使用。

6.检查字符串，过滤or,and ',&,+,,,'',

/// <summary>
        /// 字符串处理过滤or,and ',&,+,,,'',
        /// </summary>
        /// <returns></returns>
        public static string newstr(string str)
        {

            //过滤or,and ',&,+,,,'',
            String nstr = str.Replace("'", "").Replace("&", "").Replace(",", "").Replace("''", "");
            return nstr;
        }

7.获取客户端IP地址

#region 获取IP地址

/// <summary>
/// 获访问者的IP地址
/// xujh2 20140902
/// </summary>
[WebMethod]
public void getUserIp()
{
try
{
string result = System.Web.HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
//可能有代理
if (!string.IsNullOrWhiteSpace(result))
{
//没有"." 肯定是非IP格式
if (result.IndexOf(".") == -1)
{
HttpContextRequestEnd(failedEntity.retJsonError(reErrJson.error29));
return;
}
else
{
//有","，估计多个代理。取第一个不是内网的IP。
if (result.IndexOf(",") != -1)
{
result = result.Replace(" ", string.Empty).Replace("\"", string.Empty);
string[] temparyip = result.Split(",;".ToCharArray());
if (temparyip != null && temparyip.Length > 0)
{
for (int i = 0; i < temparyip.Length; i++)
{
//找到不是内网的地址
if (IsIPAddress(temparyip[i]) && temparyip[i].Substring(0, 3) != "10." && temparyip[i].Substring(0, 7) != "192.168" && temparyip[i].Substring(0, 7) != "172.16.")
{
HttpContextRequestEnd(temparyip[i].ToString().Trim());
return;
}
}
}
}
//代理即是IP格式
else if (IsIPAddress(result))
{
result = System.Web.HttpContext.Current.Request.UserHostAddress;
HttpContextRequestEnd(result.ToString().Trim());
return;
}
//代理中的内容非IP
else
{
HttpContextRequestEnd(result.ToString().Trim());
return;
}
}
}
//如果非代理IP则获取真正的IP
if (string.IsNullOrWhiteSpace(result))
{
result = System.Web.HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
HttpContextRequestEnd(result.ToString().Trim());
return;
}
//如果前面两者都不是则获取近似的IP地址
if (string.IsNullOrWhiteSpace(result))
{
result = System.Web.HttpContext.Current.Request.UserHostAddress;
HttpContextRequestEnd(result.ToString().Trim());
return;
}
}
catch (Exception)
{
HttpContextRequestEnd(failedEntity.retJsonError(reErrJson.error0));
return;
}
//return "Hello World";
}

#endregion

原文地址：https://www.cnblogs.com/xulang/p/5506207.html

C#中 常用的方法

C#中常用的方法