C#根据指定url下载文件并读取.csv数据转为json格式

从一个地址中下载Excel表格，然后读取这个Excel表格数据

注：表格是.csv格式的，我试了一下其他格式的这个程序不支持，晚点续更using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Net;
using System.Data;
using System.Data.OleDb;
using System.Text.RegularExpressions;

namespace DownLoadExcel
{
public class DownLoadRead
{
private static string directory = System.Configuration.ConfigurationManager.AppSettings["Download_Dic"];//存放地址
private static string url = System.Configuration.ConfigurationManager.AppSettings["url"];//下载地址

/// <summary>
/// 从指定url下载csv数据，然后给文件根据下载时间命名，返回文件名
/// </summary>
/// <param name="url">下载地址</param>
/// <returns>文件名称</returns>
public string DownloadFile()
{
try
{
string fileName = CreateFileName(url);
if (!Directory.Exists(directory))//判断指定路径下是否存在指定的文件夹或文件
{
Directory.CreateDirectory(directory);//创建路径下的文件夹
}
WebClient client = new WebClient();
client.DownloadFile(url, directory + fileName);
string datajson=CsvRead(0, directory + fileName);//读取excel表中数据
//另一种方法，将文件地址封装
Dictionary<string, string> dic = new Dictionary<string, string>();
dic.Add("DownExcellocation", directory + fileName);
//csvRead(0, dic["DownExcellocation"]);

return fileName;
}
catch
{
return "";
}
}

/// <summary>
/// 创建文件名称
/// </summary>
public static string CreateFileName(string url)
{
string fileName = "";
string fileExt = url.Substring(url.LastIndexOf(".")).Trim().ToLower();
//Random rnd = new Random();
//fileName = DateTime.Now.ToString("yyyyMMddHHmmssfff") + rnd.Next(10, 99).ToString() + fileExt;//获取随机数
fileName = DateTime.Now.ToString("yyyyMMddHHmmssfff") + System.Guid.NewGuid().ToString().Replace("-", "") + fileExt;
return fileName;

}

/// <summary>
/// 将Csv读入DataTable 及返回json数据
/// </summary>
/// <param name="filePath">csv文件路径</param>
/// <param name="n">表示第n行是字段title,第n+1行是记录开始</param>
/// <param name="k">可选参数表示最后K行不算记录默认0</param>
public string CsvRead(int n, string filePath)
{
DataTable dt = new DataTable();
String csvSplitBy = "(?<=^|,)(\"(?:[^\"]|\"\")*\"|[^,]*)";
StreamReader reader = new StreamReader(filePath, System.Text.Encoding.Default, false);
int i = 0, m = 0;
reader.Peek();
while (reader.Peek() > 0)
{
m = m + 1;
string str = reader.ReadLine();
if (m >= n + 1)
{
if (m == n + 1) //如果是字段行，则自动加入字段。
{
MatchCollection mcs = Regex.Matches(str, csvSplitBy);
foreach (Match mc in mcs)
{
dt.Columns.Add(mc.Value); //增加列标题
}

}
else
{
MatchCollection mcs = Regex.Matches(str, "(?<=^|,)(\"(?:[^\"]|\"\")*\"|[^,]*)");
i = 0;
System.Data.DataRow dr = dt.NewRow();
foreach (Match mc in mcs)
{
dr[i] = mc.Value;
i++;
}
dt.Rows.Add(dr); //DataTable 增加一行
}

}
}
string excelJson = DataTableToJson(dt);
Console.WriteLine(excelJson);
return excelJson;
}

#region 帮助类DataSet转换为Json
/// <summary>
/// DataSet转换为Json
/// </summary>
/// <param name="dataSet">DataSet对象</param>
/// <returns>Json字符串</returns>
public static string DataSetToJson(DataSet dataSet)
{
string jsonString = "{";
foreach (DataTable tab
aac6
le in dataSet.Tables)
{
jsonString += "\"" + table.TableName + "\":" + DataTableToJson(table) + ",";
}
jsonString = jsonString.TrimEnd(',');
return jsonString + "}";
}
#endregion
#region 帮助类Datatable转换为Json
/// <summary>
/// Datatable转换为Json
/// </summary>
/// <param name="table">Datatable对象</param>
/// <returns>Json字符串</returns>
public static string DataTableToJson(DataTable dt)
{
StringBuilder jsonString = new StringBuilder();
jsonString.Append("[");
DataRowCollection drc = dt.Rows;
for (int i = 0; i < drc.Count; i++)
{
jsonString.Append("{");
for (int j = 0; j < dt.Columns.Count; j++)
{
string strKey = dt.Columns[j].ColumnName;
string strValue = drc[i][j].ToString();
Type type = dt.Columns[j].DataType;
jsonString.Append("\"" + strKey + "\":");
strValue = StringFormat(strValue, type);
if (j < dt.Columns.Count - 1)
{
jsonString.Append(strValue + ",");
}
else
{
jsonString.Append(strValue);
}
}
jsonString.Append("},");
}
jsonString.Remove(jsonString.Length - 1, 1);
jsonString.Append("]");
return jsonString.ToString();
}
#endregion

#region 帮助类格式化字符型、日期型、布尔型StringFormat
/// <summary>
/// 格式化字符型、日期型、布尔型
/// </summary>
/// <param name="str"></param>
/// <param name="type"></param>
/// <returns></returns>
private static string StringFormat(string str, Type type)
{
if (type == typeof(string))
{
str = String2Json(str);
str = "\"" + str + "\"";
}
else if (type == typeof(DateTime))
{
str = "\"" + str + "\"";
}
else if (type == typeof(bool))
{
str = str.ToLower();
}
else if (type != typeof(string) && string.IsNullOrEmpty(str))
{
str = "\"" + str + "\"";
}
return str;
}
#endregion

#region 过滤特殊字符String2Json(String s)

/// <summary>
/// 过滤特殊字符
/// </summary>
/// <param name="s">字符串</param>
/// <returns>json字符串</returns>
private static string String2Json(String s)
{
StringBuilder sb = new StringBuilder();
for (int i = 0; i < s.Length; i++)
{
char c = s.ToCharArray()[i];
switch (c)
{
case '\"':
sb.Append("\\\""); break;
case '\\':
sb.Append("\\\\"); break;
case '/':
sb.Append("\\/"); break;
case '\b':
sb.Append("\\b"); break;
case '\f':
sb.Append("\\f"); break;
case '\n':
sb.Append("\\n"); break;
case '\r':
sb.Append("\\r"); break;
case '\t':
sb.Append("\\t"); break;
default:
sb.Append(c); break;
}
}
return sb.ToString();
}
#endregion
}
}

以上是主要方法，下面提供main方法

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

namespace DownLoadTest
{
class Program
{
static void Main(string[] args)
{
DownLoadExcel.DownLoadRead dr = new DownLoadExcel.DownLoadRead();
string filename = dr.DownloadFile();
if (!string.IsNullOrEmpty(filename))
{
Console.WriteLine("文件下载成功，文件名称：" + filename);
}
else
{
Console.WriteLine("文件下载失败");
}
Console.ReadLine();

}

}
}

运行结果：