c#简单实现生成csv文件

最近项目中用到Sql Server的DtS数据导入功能。其中dtsx模板的制作和csv的生成是重中之中。在这方面，自己完全是个菜鸟，尤其是dtsx，那玩意让我栽了很多次，幸亏在同事的热心帮助下最终让我得偿所愿，哈哈，真不容易。好了，闲言少叙，下面就记录下自己实现的一个简单的生成csv文件的方式。代码如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using System.IO;

namespace DotNet.Common.Util
{
    public static class CsvHelper
    {
        /// <summary>
        /// 保存csv文件
        /// </summary>
        /// <param name="fileName"></param>
        /// <param name="content"></param>
        public static bool SaveAsCSV<T>(string fileName, IList<T> listModel) where T : class, new()
        {
            bool flag = false;
            try
            {
                StringBuilder sb = new StringBuilder();
                //通过反射 显示要显示的列
                BindingFlags bf = BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static;//反射标识
                Type objType = typeof(T);
                PropertyInfo[] propInfoArr = objType.GetProperties(bf);
                string header = string.Empty;
                List<string> listPropertys = new List<string>();
                foreach (PropertyInfo info in propInfoArr)
                {
                    if (string.Compare(info.Name.ToUpper(), "ID") != 0) //不考虑自增长的id或者自动生成的guid等
                    {
                        if (!listPropertys.Contains(info.Name))
                        {
                            listPropertys.Add(info.Name);
                        }
                        header += info.Name + ",";
                    }
                }
                sb.AppendLine(header.Trim(',')); //csv头

                foreach (T model in listModel)
                {
                    string strModel = string.Empty;
                    foreach (string strProp in listPropertys)
                    {
                        foreach (PropertyInfo propInfo in propInfoArr)
                        {
                            if (string.Compare(propInfo.Name.ToUpper(), strProp.ToUpper()) == 0)
                            {
                                PropertyInfo modelProperty = model.GetType().GetProperty(propInfo.Name);
                                if (modelProperty != null)
                                {
                                    object objResult = modelProperty.GetValue(model, null);
                                    string result = ((objResult == null) ? string.Empty : objResult).ToString().Trim();
                                    if (result.IndexOf(',') != -1)
                                    {
                                        result = "\"" + result.Replace("\"", "\"\"") + "\""; //特殊字符处理 ？
                                        //result = result.Replace("\"", "“").Replace(',', '，') + "\"";
                                    }
                                    if (!string.IsNullOrEmpty(result))
                                    {
                                        Type valueType = modelProperty.PropertyType;
                                        if (valueType.Equals(typeof(Nullable<decimal>)))
                                        {
                                            result = decimal.Parse(result).ToString("#.#");
                                        }
                                        else if (valueType.Equals(typeof(decimal)))
                                        {
                                            result = decimal.Parse(result).ToString("#.#");
                                        }
                                        else if (valueType.Equals(typeof(Nullable<double>)))
                                        {
                                            result = double.Parse(result).ToString("#.#");
                                        }
                                        else if (valueType.Equals(typeof(double)))
                                        {
                                            result = double.Parse(result).ToString("#.#");
                                        }
                                        else if (valueType.Equals(typeof(Nullable<float>)))
                                        {
                                            result = float.Parse(result).ToString("#.#");
                                        }
                                        else if (valueType.Equals(typeof(float)))
                                        {
                                            result = float.Parse(result).ToString("#.#");
                                        }
                                    }
                                    strModel += result + ",";
                                }
                                else
                                {
                                    strModel += ",";
                                }
　　　　　　　　　　　　　　　　　　break;
                            }
                        }
                    }
                    strModel = strModel.Substring(0, strModel.Length - 1);
                    sb.AppendLine(strModel);
                }
                string content = sb.ToString();
                string dir = Directory.GetCurrentDirectory();
                string fullName = Path.Combine(dir, fileName);
                if (File.Exists(fullName)) File.Delete(fullName);
                using (FileStream fs = new FileStream(fullName, FileMode.CreateNew, FileAccess.Write))
                {
                    StreamWriter sw = new StreamWriter(fs, Encoding.Default);
                    sw.Flush();
                    sw.Write(content);
                    sw.Flush();
                    sw.Close();
                }
                flag = true;
            }
            catch
            {
                flag = false;
            }
            return flag;
        }
    }
}

需要说明的是：
1、生成csv的时候，我们没有考虑实体类和数据库字段的顺序，只是通过反射遍历属性而已。如果要更加直观地看到dtsx模板导出列和csv导入列之间的关系，建议实体类和数据库的字段顺序一致。
2、对于海量数据，这个方法的StringBuilder在保存字符串的时候会有明显的性能问题。这个地方还可以改进，改进的方法请关注老赵的这一篇和即将出现的下一篇。
3、这个生成csv文件的方式不是很灵活，您可以改进成自己需要的方式，比如列名，写入列顺序等自己来配置。
ps：有小数点的数值型保留几位小数看实际项目需要，本文统一保存为1位小数（ToString("#.#")的形式）。