C# 扩展方法实际应用整理
由于在项目中经常要针对基本的类型进行处理，因此写了如下的扩展类进行类的扩展。
using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Collections;using System.Text;using System.Text.RegularExpressions;using System.Data;/// <summary>///StringExtender 的摘要说明/// </summary>public static class StringExtender{ #region Hashtable 扩展 /// <summary> /// 尝试将键和值添加到字典中：如果不存在，才添加；存在，不添加也不抛导常 /// </summary> public static Hashtable TryAdd<TKey, TValue>(this Hashtable dict, TKey key, TValue value) { if (dict.ContainsKey(key) == false) dict.Add(key, value); return dict; } /// <summary> /// 将键和值添加或替换到字典中：如果不存在，则添加；存在，则替换 /// </summary> public static Hashtable AddOrReplace<TKey, TValue>(this Hashtable dict, TKey key, TValue value) { dict[key] = value; return dict; } /// <summary> /// 获取与指定的键相关联的值，如果没有则返回输入的默认值 /// </summary> public static TValue GetValue<TKey, TValue>(this Hashtable dict, TKey key, TValue defaultValue = default(TValue)) { return dict.ContainsKey(key) ? (TValue)dict[key] : defaultValue; } /// <summary> /// 向字典中批量添加键值对 /// </summary> /// <param name="replaceExisted">如果已存在，是否替换</param> public static Hashtable AddRange<TKey, TValue>(this Hashtable dict, IEnumerable<KeyValuePair<TKey, TValue>> values, bool replaceExisted) { foreach (var item in values) { if (dict.ContainsKey(item.Key) == false || replaceExisted) dict[item.Key] = item.Value; } return dict; } #endregion #region Dictionary<TKey, TValue>扩展 /// <summary> /// 尝试将键和值添加到字典中：如果不存在，才添加；存在，不添加也不抛导常 /// </summary> public static Dictionary<TKey, TValue> TryAdd<TKey, TValue>(this Dictionary<TKey, TValue> dict, TKey key, TValue value) { if (dict.ContainsKey(key) == false) dict.Add(key, value); return dict; } /// <summary> /// 将键和值添加或替换到字典中：如果不存在，则添加；存在，则替换 /// </summary> public static Dictionary<TKey, TValue> AddOrReplace<TKey, TValue>(this Dictionary<TKey, TValue> dict, TKey key, TValue value) { dict[key] = value; return dict; } /// <summary> /// 获取与指定的键相关联的值，如果没有则返回输入的默认值 /// </summary> public static TValue GetValue<TKey, TValue>(this Dictionary<TKey, TValue> dict, TKey key, TValue defaultValue = default(TValue)) { return dict.ContainsKey(key) ? dict[key] : defaultValue; } /// <summary> /// 向字典中批量添加键值对 /// </summary> /// <param name="replaceExisted">如果已存在，是否替换</param> public static Dictionary<TKey, TValue> AddRange<TKey, TValue>(this Dictionary<TKey, TValue> dict, IEnumerable<KeyValuePair<TKey, TValue>> values, bool replaceExisted) { foreach (var item in values) { if (dict.ContainsKey(item.Key) == false || replaceExisted) dict[item.Key] = item.Value; } return dict; } #endregion /// <summary> /// 将给定的对象转化为string[] ，ArrayList，List<string>，object[] /// </summary> /// <param name="obj"></param> /// <returns></returns> public static string[] ToArrayStr(this object obj) { string[] arrStr = null; if (IsNullOrEmpty(obj)) { return arrStr; } if (obj.GetType() == typeof(ArrayList)) { ArrayList arr = obj as ArrayList; arrStr = arr.ToArray(typeof(string)) as string[]; } else if (obj.GetType() == typeof(List<string>)) { List<string> list = obj as List<string>; arrStr = list.ToArray(); } else if (obj.GetType() == typeof(object[])) { object[] list = obj as object[]; arrStr = (string[])ArrayList.Adapter((Array)list).ToArray(typeof(string)); } return arrStr; } /// <summary> /// 给定的数组转化为ArrayList /// </summary> /// <param name="array"></param> /// <returns></returns> public static ArrayList ToArrayList(this string[] array) { if (array == null) return null; ArrayList list = new ArrayList(); foreach (string str in array) { list.Add(str); } return list; } public static string _ToString(this string[] array, string Separated) { string Result = ""; if (array == null) { return Result; } foreach (string a in array) { Result += a + Separated; } Result = Result.Substring(0, Result.Length - Separated.Length); return Result; } /// <summary> /// 转换为枚举，忽略大小写 /// </summary> /// <param name="EnumVal"></param> /// <param name="EnumType"></param> /// <returns></returns> public static object ToEnum(this string EnumVal, Type EnumType, bool ignoreCase) { object oEnum = Enum.Parse(EnumType, EnumVal, ignoreCase); return oEnum; } /// <summary> /// 转换为枚举，忽略大小写 /// </summary> /// <param name="EnumVal"></param> /// <param name="EnumType"></param> /// <returns></returns> public static object ToEnum(this string EnumVal, Type EnumType) { return ToEnum(EnumVal, EnumType, true); } public static int IndexOf(this string[] array, string Value) { int Result = -1; for (int i = 0; i < array.Length; i++) { if (array[i] == Value) { Result = i; break; } } return Result; } /// <summary> /// 将 ▓A▓▓NA▓ 转化为 'A','NA' 格式 /// </summary> /// <param name="str"></param> /// <returns></returns> public static string GetSqlIn(this object obj) { return obj.ReplaceX(TBCSysConst.SPLIT_STR + TBCSysConst.SPLIT_STR, "','").ReplaceX(TBCSysConst.SPLIT_STR, "'"); } /// <summary> /// ArrayList,string[],Array,string, 把以","分隔的字符串，转变为在SQL中可直接运行的字符串 /// 111,www,rrrr 变成 '111','www','rrr' /// </summary> /// <param name="str"></param> /// <param name="Separated"></param> /// <returns></returns> public static string GetStringSqlFilter(this object str) { StringBuilder builder = new StringBuilder(); if (str.GetType() == typeof(ArrayList)) { ArrayList list = str as ArrayList; foreach (string temp in list) { builder.AppendFormat(",'{0}'", temp.Replace("'", string.Empty)); } } else if (str.GetType() == typeof(string[])) { string[] list = str as string[]; foreach (string temp in list) { builder.AppendFormat(",'{0}'", temp.Replace("'", string.Empty)); } } else if (str.GetType() == typeof(Array)) { Array list = str as Array; foreach (string temp in list) { builder.AppendFormat(",'{0}'", temp.Replace("'", string.Empty)); } } else if (str.GetType() == typeof(string)) { string[] arrStr = str.ToList(","); foreach (string temp in arrStr) { builder.AppendFormat(",'{0}'", temp.Replace("'", string.Empty)); } } if (builder.Length > 0) return builder.ToStringX().Substring(1); else return string.Empty; } /// <summary> /// 去除空格 /// </summary> /// <param name="str"></param> /// <param name="flag">是否去除内部的空格</param> /// <returns></returns> public static string Trim(this string str, bool flag) { if (!str.IsNullOrEmpty()) { str = (flag) ? Regex.Replace(str, @"\s+", string.Empty) : str.Trim(); } return str; } /// <summary> /// 将字符串转化为数字 /// </summary> /// <param name="item">转化失败返回0</param> /// <returns></returns> public static int ToInt(this object item) { int IntResult = 0; if (!item.IsNullOrEmpty()) { int.TryParse(item.ToStringX(), out IntResult); } return IntResult; } /// <summary> /// 将字符串转化为金额 /// </summary> /// <param name="item">转化失败返回0</param> /// <returns></returns> public static double ToMoney(this object item) { double IntResult = 0.00; if (!item.IsNullOrEmpty()) { double.TryParse(item.ToString(), out IntResult); } return IntResult; } /// <summary> /// 将字符串转化为金额 /// </summary> /// <param name="item">转化失败返回0</param> /// <returns></returns> public static decimal ToMoney(this object item, int Num) { decimal DecResult = decimal.Zero; if (!item.IsNullOrEmpty()) { decimal.TryParse(item.ToString(), out DecResult); DecResult = decimal.Round(DecResult, Num); } return DecResult; } /// <summary> /// 查看字符串是否匹配指定的正则表达式 如 "12345".IsMatch(@"\d+"); /// </summary> /// <param name="s"></param> /// <param name="pattern"></param> /// <returns></returns> public static bool IsMatch(this string s, string pattern) { if (s == null) return false; else return Regex.IsMatch(s, pattern); } /// <summary> /// 将匹配的字符串过滤返回 如 "ljn615".Match("[a-zA-Z]+"); /// </summary> /// <param name="s"></param> /// <param name="pattern"></param> /// <returns></returns> public static string Match(this string s, string pattern) { if (s == null) return string.Empty; return Regex.Match(s, pattern).Value; } /// <summary> /// 判断字符是否为空或者NULL,true则为空,false不为空 /// </summary> /// <param name="value"></param> /// <returns></returns> public static bool IsNullOrEmpty(this object value) { if (value != null && value != DBNull.Value) { Type objType = value.GetType(); if (objType == typeof(DataSet)) { DataSet ds = value as DataSet; //没有表 if (ds.Tables.Count == 0) return true; //只有一个表，但是表里没有数据 if (ds.Tables.Count == 1 && ds.Tables[0].Rows.Count == 0) return true; if (ds.Tables.Count > 1) { foreach (DataTable dt in ds.Tables) { //只要有大于0的就不为空 if (dt.Rows.Count > 0) { return false; } } } } if (objType == typeof(DataTable)) { DataTable dt = value as DataTable; if (dt.Rows.Count == 0) return true; } string val = value.ToString().Trim().ToUpper(); if (val == "NULL" || val == "UNDEFINED" || val == "{}") return true; return (val.Length == 0); } return true; } /// <summary> /// 格式化字符串 /// </summary> /// <param name="format">要格式化的字符串,如 "今天是：{0:yyyy年MM月dd日 星期ddd}".FormatWith(DateTime.Today);</param> /// <param name="args">可选的</param> /// <returns></returns> public static string FormatWith(this string format, params object[] args) { return string.Format(format, args); } /// <summary> /// 将对象内指定的字符串(不区分大小写)替换为新的字符串,如果为null则返回空字符串 /// </summary> /// <param name="item"></param> /// <param name="OldStr">被替换的字符串</param> /// <param name="NewStr">新的字符串</param> /// <returns></returns> public static string ReplaceX(this object item, string OldStr, string NewStr) { string StrResult = string.Empty; if (!item.IsNullOrEmpty()) { StrResult = item.ToString().Trim().Replace(OldStr, NewStr).Replace(OldStr.ToLower(), NewStr).Replace(OldStr.ToUpper(), NewStr); } return StrResult; } /// <summary> /// 将对象转化为字符串后并截取字符 /// </summary> /// <param name="item"></param> /// <param name="start">开始截取的索引</param> /// <returns></returns> public static string ToStringX(this object item, int start) { string StrResult = string.Empty; if (!item.IsNullOrEmpty()) { StrResult = item.ToString().Trim(); if (start < StrResult.Length) { StrResult = StrResult.Substring(start); } } return StrResult; } /// <summary> /// 将对象转化为字符串后并截取字符 /// </summary> /// <param name="item"></param> /// <param name="start">开始截取的索引</param> /// <param name="length">要截取的长度</param> /// <returns></returns> public static string ToStringX(this object item, int start, int length) { string StrResult = string.Empty; if (!item.IsNullOrEmpty()) { StrResult = item.ToString().Trim(); if (length <= StrResult.Length - start) { StrResult = StrResult.Substring(start, length); } } return StrResult; } /// <summary> /// 将对象转化为字符串,如果为null则返回空字符串 /// </summary> /// <param name="item"></param> /// <param name="flag">可选的,是否去掉空格</param> /// <returns></returns> public static string ToStringX(this object item) { string StrResult = string.Empty; if (!item.IsNullOrEmpty()) { if (item.GetType() == typeof(byte[])) { byte[] b = item as byte[]; StrResult = Encoding.Default.GetString(b); } else { StrResult = item.ToString().Trim(); } } return StrResult; } /// <summary> /// 将对象转化为字符串,如果为null则返回空字符串 /// </summary> /// <param name="item"></param> /// <param name="flag">可选的,是否转换成大写，否则false小写</param> /// <returns></returns> public static string ToStringX(this object item, bool flag) { string StrResult = string.Empty; if (!item.IsNullOrEmpty()) { if (flag) StrResult = item.ToString().Trim().ToUpper(); else StrResult = item.ToString().Trim().ToLower(); } return StrResult; } /// <summary> /// 将字符串以指定的分隔符转换成数组 /// </summary> /// <param name="item"></param> /// <param name="Separated">分隔符</param> /// <returns></returns> public static string[] ToList(this object item, char Separated) { return ToList(item, Separated.ToString()); } /// <summary> /// 将字符串以指定的分隔符转换成数组 /// </summary> /// <param name="item"></param> /// <param name="Separated">分隔符</param> /// <returns></returns> public static string[] ToList(this object item, string Separated) { string StrResult = item.ToStringX(); string[] arrResult = null; if (!Separated.IsNullOrEmpty() && StrResult.Contains(Separated)) { StrResult = StrResult.Replace(Separated, TBCSysConst.REPLACE_SPLIT_CHAR.ToString()); arrResult = StrResult.Split(TBCSysConst.REPLACE_SPLIT_CHAR); } else { arrResult = new string[] { StrResult }; } return arrResult; } /// <summary> /// 转全角(SBC case) /// </summary> /// <param name="input">任意字符串</param> /// <returns>全角字符串</returns> public static string ToSBC(this string input) { char[] c = input.ToCharArray(); for (int i = 0; i < c.Length; i++) { if (c[i] == 32) { c[i] = (char)12288; continue; } if (c[i] < 127) { c[i] = (char)(c[i] + 65248); } } return new string(c); } /// <summary> /// 转半角(DBC case) /// </summary> /// <param name="input">任意字符串</param> /// <returns>半角字符串</returns> public static string ToDBC(this string input) { char[] c = input.ToCharArray(); for (int i = 0; i < c.Length; i++) { if (c[i] == 12288) { c[i] = (char)32; continue; } if (c[i] > 65280 && c[i] < 65375) { c[i] = (char)(c[i] - 65248); } } return new string(c); } /// <summary> /// 将对象转化为字符串,如果为null则返回空字符串 /// </summary> /// <param name="item"></param> /// <param name="flag">可选的,是否去掉空格</param> /// <returns></returns> public static string ToStringX(this object item, FormatEnum format) { string StrResult = string.Empty; if (!item.IsNullOrEmpty()) { if (!format.IsNullOrEmpty()) { try { switch (format) { case FormatEnum.SmallDate: DateTime SmallDate = Convert.ToDateTime(item); StrResult = SmallDate.ToString("yyyy-MM-dd"); break; case FormatEnum.FullDate: DateTime FullDate = Convert.ToDateTime(item); StrResult = FullDate.ToString("yyyy-MM-dd HH:mm:ss"); break; case FormatEnum.FileReName: DateTime FileReName = Convert.ToDateTime(item); StrResult = FileReName.ToString("yyyyMMddHHmmss"); break; case FormatEnum.SmallYear: DateTime SmallYear = Convert.ToDateTime(item); StrResult = SmallYear.ToString("yyyyMMdd"); break; default: break; } } catch (Exception) { StrResult = item.ToString().Trim(); } } else StrResult = item.ToString().Trim(); } return StrResult; }}/// <summary>/// 格式化的枚举/// </summary>public enum FormatEnum{ /// <summary> /// yyyy-MM-dd /// </summary> SmallDate = 0, /// <summary> /// yyyyMMdd /// </summary> SmallYear, /// <summary> /// yyyy-MM-dd HH:mm:ss /// </summary> FullDate, /// <summary> /// yyyyMMddHHmmss /// </summary> FileReName}