扩展方法集合类在C#中是一种特别的语法糖，可以在开发中极大简化代码的编写。主要功能是在系统类中创建自定义方法。比如字符串转数字，每次都得Convert.ToInt32 (str)，从语法上来说就太不简洁了。下面我一步一步讲解扩展方法集合类的编写。首先创建一个静态类，类名必须为ExtensionMethods。示例代码如下
1 2 3 | public static class ExtensionMethods { //... } |
所有扩展方法都需要放在此类中进行实现。首先创建一个静态函数，第一个参数使用this描述符，表示基于哪个类提供扩展方法
1 2 3 | public static Int32 toInt32 (this object o) { return Convert.ToInt32 (o); } |
此函数代表在object这个类基础上新增一个扩展方法，无参数，返回值为Int32类型。示例调用代码如下：
1 | int t = "123".toInt32(); |
下面我提供一个我自用的扩展方法集合类供参阅
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 | //////////////////////////////////////////////////////////////////////////////// // // Class Name: ExtensionMethods // Description: C#扩展方法集合类 // Class URI: https://www.fawdlstty.com/archives/411.html // Author: Fawdlstty // Author URI: https://www.fawdlstty.com/ // Version: 0.1 // License: MIT // Last Update: Jun 25, 2017 // //////////////////////////////////////////////////////////////////////////////// using System; using System.Text; namespace docx_to_xlsx { public static class ExtensionMethods { /// <summary> /// 返回元素在数组中的索引 /// </summary> /// <param name="a">数组</param> /// <param name="o">元素</param> /// <returns>索引</returns> public static int inArray (this object [] a, object o) { for (int i = 0; i < a.Length; i++) { if (a [i] == o) return i; } return -1; } /// <summary> /// 返回元素在数组中的索引 /// </summary> /// <param name="o">元素</param> /// <param name="a">数组</param> /// <returns>索引</returns> public static int inArray (this object o, object [] a) { return a.inArray (o); } /// <summary> /// URL转码 /// </summary> /// <param name="s">原始URL</param> /// <returns>新URL</returns> public static string encodeUrl (this string s) { if (s.isNullOrEmpty ()) return ""; return s.Replace (":", "%3a").Replace ("/", "%2f").Replace (" ", "+").Replace ("\\", "%2c").Replace ("=", "%3d").Replace ("?", "%3f").Replace ("%", "%25").Replace ("&", "%26"); } /// <summary> /// 简化string.Format函数的调用 /// </summary> /// <param name="s">格式化字符串</param> /// <param name="args">参数列表</param> /// <returns>格式化后的字符串</returns> public static string format (this string s, params object [] args) { return string.Format (s, args); } /// <summary> /// 简化Convert.ToInt32函数的调用 /// </summary> /// <param name="o">需要转为数字的对象</param> /// <returns>数字</returns> public static Int32 toInt32 (this object o) { try { return Convert.ToInt32 (o); } catch (Exception ex) { throw ex; } } /// <summary> /// 简化Convert.ToInt64函数的调用 /// </summary> /// <param name="o">需要转为数字的对象</param> /// <returns>数字</returns> public static Int64 toInt64 (this object o) { try { return Convert.ToInt64 (o); } catch (Exception ex) { throw ex; } } /// <summary> /// 简化Convert.ToDouble函数的调用 /// </summary> /// <param name="o">需要转为数字的对象</param> /// <returns>数字</returns> public static double toDouble (this object o) { try { return Convert.ToDouble (o); } catch (Exception ex) { throw ex; } } public static int hex_to_dec (this String s) { try { return Convert.ToInt32 (s, 16); } catch (Exception ex) { throw ex; } } ///// <summary> ///// MD5加密 ///// </summary> ///// <param name="s">需要加密的数据</param> ///// <param name="loop">加密次数</param> ///// <returns>加密后的数据</returns> //public static string md5Encrypt (this string s, int loop = 3) { // MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider (); // for (; loop > 0; loop--) { // s = BitConverter.ToString (md5.ComputeHash (UTF8Encoding.Default.GetBytes (s))).Replace ("-", ""); // } // return "{0}-{1}-{2}-{3}-{4}".format (s.Substring (0, 8), s.Substring (8, 4), s.Substring (12, 4), s.Substring (16, 4), s.Substring (20, 12)); //} /// <summary> /// 简化string.Join函数调用 /// </summary> /// <param name="s">数组对象</param> /// <param name="separator">分隔符</param> /// <returns>字符串</returns> public static string join (this string [] s, string separator = ";") { if (s == null) return ""; return string.Join (separator, s); } /// <summary> /// 二维数组垂直string.Join函数调用 /// </summary> /// <param name="ss">数组对象</param> /// <param name="col">垂直第几列</param> /// <param name="separator">分隔符</param> /// <returns>字符串</returns> public static string join (this string [] [] ss, int col, string separator = ";") { if (ss == null || ss.Length == 0) return ""; StringBuilder sb = new StringBuilder (); for (int i = 0; i < ss.Length; i++) { sb.Append (ss [i] [col]).Append (separator); } return sb.Remove (sb.Length - separator.Length, separator.Length).toString (); } /// <summary> /// 简化string.IsNullOrEmpty函数调用 /// </summary> /// <param name="s">字符串</param> /// <returns>是否为空</returns> public static bool isNullOrEmpty (this string s) { return string.IsNullOrEmpty (s); } /// <summary> /// 字符串或其他类型转为日期时间对象 /// </summary> /// <param name="o">需要转换的对象</param> /// <returns>日期时间类型</returns> public static DateTime toDateTime (this object o) { try { return Convert.ToDateTime (o); } catch (Exception ex) { throw ex; } } /// <summary> /// 格式化小数 /// </summary> /// <param name="o">需要格式化小数的对象</param> /// <param name="afterPoint">保留小数点后几位</param> /// <returns>字符串型数据</returns> public static string formatDecimal (this object o, int afterPoint = 2) { try { return string.Format (string.Format ("{{0:F{0}}}", afterPoint), o); } catch (Exception ex) { throw ex; } } /// <summary> /// 格式化日期 /// </summary> /// <param name="o">需要格式化的日期</param> /// <param name="sDate">日期分隔符</param> /// <returns>字符串</returns> public static string formatDate (this DateTime o, char sDate = '-') { if (o == null) return ""; return o.ToString (string.Format ("yyyy{0}MM{0}dd", sDate)); } /// <summary> /// 格式化日期（汉字） /// </summary> /// <param name="o">需要格式化的日期</param> /// <returns>字符串</returns> public static string formatDateLong (this DateTime o) { if (o == null) return ""; return o.ToString ("yyyy年MM月dd日"); } /// <summary> /// 格式化时间 /// </summary> /// <param name="o">需要被格式化的时间</param> /// <param name="sTime">分隔符，默认冒号</param> /// <returns>格式化后的时间</returns> public static string formatTime (this DateTime o, char sTime = ':') { if (o == null) return ""; return o.ToString (string.Format ("HH{0}mm{0}ss", sTime)); } /// <summary> /// 格式化时间（汉字） /// </summary> /// <param name="o">需要被格式化的时间</param> /// <returns>格式化后的时间</returns> public static string formatTimeLong (this DateTime o) { if (o == null) return ""; return o.ToString ("HH时mm分ss秒"); } /// <summary> /// 格式化日期时间 /// </summary> /// <param name="o">需要格式化的日期时间</param> /// <param name="sDate">日期分隔符</param> /// <param name="sTime">时间分隔符</param> /// <returns>字符串</returns> public static string formatDateTime (this DateTime o, char sDate = '-', char sTime = ':') { if (o == null) return ""; return string.Format ("{0} {1}", o.formatDate (sDate), o.formatTime (sTime)); } /// <summary> /// 格式化日期时间（汉字） /// </summary> /// <param name="o">需要格式化的日期时间</param> /// <returns>字符串</returns> public static string formatDateTimeLong (this DateTime o) { if (o == null) return ""; return string.Format ("{0} {1}", o.formatDateLong (), o.formatTimeLong ()); } /// <summary> /// 将布尔值转为字符串 /// </summary> /// <param name="b">布尔值</param> /// <returns>字符串</returns> public static string boolToString (this bool b) { try { return b ? "ok" : "fealure"; } catch (Exception ex) { return ex.Message; } } ///// <summary> ///// 将一个对象序列化为json字符串 ///// </summary> ///// <param name="o">可序列化对象</param> ///// <returns>json字符串</returns> //public static string toJson (this object o) { // try { // if (o == null) return "[]"; // return new JavaScriptSerializer ().Serialize (o); // } catch (Exception ex) { // return ex.Message; // } //} ///// <summary> ///// 将json字符串反序列化为一个对象 ///// </summary> ///// <typeparam name="T">返回值类型</typeparam> ///// <param name="s">json字符串</param> ///// <returns>反序列化后的对象</returns> //public static T fromJson<T> (this string s) { // try { // if (s.isNullOrEmpty ()) return default (T); // return new JavaScriptSerializer ().Deserialize<T> (s); // } catch (Exception ex) { // throw ex; // } //} /// <summary> /// 用于可能为空的对象转字符串，避免对象为空引发的错误 /// </summary> /// <param name="o">object对象</param> /// <returns>字符串</returns> public static string toString (this object o) { if (o == null) return ""; return o.ToString (); } /// <summary> /// 向上取整 /// </summary> /// <param name="n">浮点数</param> /// <returns>计算结果</returns> public static int cell (this double d) { int i = (int) d; if (d > i) return i + 1; return i; } /// <summary> /// 向下取整 /// </summary> /// <param name="n">浮点数</param> /// <returns>计算结果</returns> public static int floor (this double d) { return (int) d; } //供ID检查用 private static Func<char, bool> isSign = c => (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F'); /// <summary> /// 检查是否为标准32位ID格式 /// </summary> /// <param name="s">ID</param> /// <returns>是否标准</returns> public static bool isId32 (this string s) { if (s.isNullOrEmpty () || s.Length != 32) return false; for (int i = 0; i < s.Length; i++) { if (!isSign (s [i])) return false; } return true; } /// <summary> /// 检查是否为标准36位ID格式 /// </summary> /// <param name="s">ID</param> /// <returns>是否标准</returns> public static bool isId36 (this string s) { if (s.isNullOrEmpty () || s.Length != 36) return false; for (int i = 0; i < s.Length; i++) { if (i == 8 || i == 13 || i == 18 || i == 23) { if (s [i] != '-') return false; } else { if (!isSign (s [i])) return false; } } return true; } } } |
