一个使用C#语言写的FTP地址解析函数

最近写C#程序时遇到了一个场景，需要分析一个FTP地址各项要素，并将之放到一个Dictionary类中。于是我写了一个函数实现这一功能。

FTP地址语法定义在RFC-1738，格式为：ftp://[user[:password]@]host[:port]/url-path

其中，方括号围住的部分为选填项，user为用户名，password为密码，host为FTP地址，port为FTP端口号，url-path为地址后接的目录地址。

函数AnalyzerFtpUrl代码如下：

/// <summary>
/// 解析FTP地址
/// </summary>
/// <param name="ftpUrl"></param>
/// <returns></returns>
public static Dictionary<string, string> AnalyzeFtpUrl(string ftpUrl)
{
    Dictionary<string, string> dic = new Dictionary<string, string>();

    if (string.IsNullOrWhiteSpace(ftpUrl) || !ftpUrl.StartsWith("ftp://"))
    {
        throw new Exception("无效的FTP地址");
    }

    ftpUrl = ftpUrl.Substring(6); //去除最前面的 ftp://

    string userName = "";      //登录用户名
    string userPassword = "";  //登录密码
    string address = "";       //登录地址
    string port = "";          //端口号
    string directory = "";     //内部子目录

    string leftHalf = "";      //@左侧部分 用户名:密码
    string rightHalf = "";     //@右侧部分 登录地址:端口号/内部子目录

    //将FTP地址划分为左侧部分与右侧部分
    int half = ftpUrl.IndexOf('@');
    if (half == -1)
    {
        leftHalf = "";
        rightHalf = ftpUrl;
    }
    else
    {
        leftHalf = ftpUrl.Substring(0, half);
        rightHalf = ftpUrl.Substring(half + 1);
    }

    //解析 用户名:密码
    if (!string.IsNullOrWhiteSpace(leftHalf))
    {
        int half2 = leftHalf.IndexOf(':');
        if (half2 != -1)
        {
            userName = leftHalf.Substring(0, half2);
            userPassword = leftHalf.Substring(half2 + 1);
            if (string.IsNullOrWhiteSpace(userName) || string.IsNullOrWhiteSpace(userPassword))
            {
                userName = "";
                userPassword = "";
            }
        }
    }

    //解析 登录地址:端口号/内部子目录
    if (!string.IsNullOrWhiteSpace(rightHalf))
    {
        int half3 = rightHalf.IndexOf('/');
        if (half3 != -1)
        {
            directory = rightHalf.Substring(half3);
            if (directory == "/")
            {
                directory = "";
            }
            rightHalf = rightHalf.Substring(0, half3);
        }

        int half4 = rightHalf.IndexOf(':');
        if (half4 == -1)
        {
            address = rightHalf;
        }
        else
        {
            address = rightHalf.Substring(0, half4);
            port = rightHalf.Substring(half4 + 1);
        }

        if (string.IsNullOrWhiteSpace(address))
        {
            throw new Exception("无效的FTP地址");
        }
    }
    else
    {
        throw new Exception("无效的FTP地址");
    }

    //添加字典项
    dic.Add("username", userName);
    dic.Add("userPassword", userPassword);
    dic.Add("address", address);
    dic.Add("port", port);
    dic.Add("directory", directory);

    return dic;
}

建立一个C#命令行应用程序，键入如下代码，其中函数AnalyzeFtpUrl已在上面给出，在此不再赘述。

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

namespace FtpUrlAnalyzer
{
    class Program
    {
        static void Main(string[] args)
        {
            PrintItem("ftp://flora:123456@127.0.0.1:1024/hi_flora/");
            PrintItem("ftp://127.0.0.1/hi_flora");
            PrintItem("ftp://127.0.0.1:1024/hi_flora");
            PrintItem("ftp://:@127.0.0.1:1024/");
            PrintItem("");
            PrintItem("123456");
            PrintItem("ftp://tsybius2014");
            PrintItem("ftp://:1024/hi_flora");

            Console.Read();
        }

        /// <summary>
        /// 打印FTP
        /// </summary>
        /// <param name="ftpUrl"></param>
        public static void PrintItem(string ftpUrl)
        {
            try
            {
                Console.WriteLine("url [ " + ftpUrl + " ]");
                Console.WriteLine("----------------------");
                Dictionary<string, string> dic = AnalyzeFtpUrl(ftpUrl);
                foreach (KeyValuePair<string, string> pair in dic)
                {
                    Console.WriteLine("key:" + pair.Key + ", value:" + pair.Value);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
                Console.WriteLine();
            }
        }

        /// <summary>
        /// 解析FTP地址
        /// </summary>
        /// <param name="ftpUrl"></param>
        /// <returns></returns>
        public static Dictionary<string, string> AnalyzeFtpUrl(string ftpUrl)
        {
            Dictionary<string, string> dic = new Dictionary<string, string>();
            //函数实现逻辑同上，故略
            return dic;
        }

    }
}

程序运行结果输出如下：

url [ ftp://flora:123456@127.0.0.1:1024/hi_flora/ ]
----------------------
key:username, value:flora
key:userPassword, value:123456
key:address, value:127.0.0.1
key:port, value:1024
key:directory, value:/hi_flora/

url [ ftp://127.0.0.1/hi_flora ]
----------------------
key:username, value:
key:userPassword, value:
key:address, value:127.0.0.1
key:port, value:
key:directory, value:/hi_flora

url [ ftp://127.0.0.1:1024/hi_flora ]
----------------------
key:username, value:
key:userPassword, value:
key:address, value:127.0.0.1
key:port, value:1024
key:directory, value:/hi_flora

url [ ftp://:@127.0.0.1:1024/ ]
----------------------
key:username, value:
key:userPassword, value:
key:address, value:127.0.0.1
key:port, value:1024
key:directory, value:

url [  ]
----------------------
System.Exception: 无效的FTP地址
   在 FtpUrlAnalyzer.Program.AnalyzeFtpUrl(String ftpUrl) 位置 d:\MyPrograms\Ftp
UrlAnalyzer\FtpUrlAnalyzer\Program.cs:行号 61
   在 FtpUrlAnalyzer.Program.PrintItem(String ftpUrl) 位置 d:\MyPrograms\FtpUrlA
nalyzer\FtpUrlAnalyzer\Program.cs:行号 34

url [ 123456 ]
----------------------
System.Exception: 无效的FTP地址
   在 FtpUrlAnalyzer.Program.AnalyzeFtpUrl(String ftpUrl) 位置 d:\MyPrograms\Ftp
UrlAnalyzer\FtpUrlAnalyzer\Program.cs:行号 61
   在 FtpUrlAnalyzer.Program.PrintItem(String ftpUrl) 位置 d:\MyPrograms\FtpUrlA
nalyzer\FtpUrlAnalyzer\Program.cs:行号 34

url [ ftp://tsybius2014 ]
----------------------
key:username, value:
key:userPassword, value:
key:address, value:tsybius2014
key:port, value:
key:directory, value:

url [ ftp://:1024/hi_flora ]
----------------------
System.Exception: 无效的FTP地址
   在 FtpUrlAnalyzer.Program.AnalyzeFtpUrl(String ftpUrl) 位置 d:\MyPrograms\Ftp
UrlAnalyzer\FtpUrlAnalyzer\Program.cs:行号 131
   在 FtpUrlAnalyzer.Program.PrintItem(String ftpUrl) 位置 d:\MyPrograms\FtpUrlA
nalyzer\FtpUrlAnalyzer\Program.cs:行号 34

END