C# 实现FTP上传下载文件

C# 实现FTP下载文件

初学C# 需要用到FTP下载文件，在这里记录一下。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.IO;
using System.Threading;

namespace FtpUtils
{
    class FtpHelper
    {
        // 默认常量定义
        private static readonly string rootPath = "/";
        private static readonly int defaultReadWriteTimeout = 300000;
        private static readonly int defaultFtpPort = 21;

        #region 设置初始化参数
        private string host = string.Empty;
        public string Host
        {
            get
            {
                return this.host ?? string.Empty;
            }
        }

        private string username = string.Empty;
        public string Username
        {
            get
            {
                return this.username;
            }
        }

        private string password = string.Empty;
        public string Password
        {
            get
            {
                return this.password;
            }
        }

        IWebProxy proxy = null;
        public IWebProxy Proxy
        {
            get
            {
                return this.proxy;
            }
            set
            {
                this.proxy = value;
            }
        }

        private int port = defaultFtpPort;
        public int Port
        {
            get
            {
                return port;
            }
            set
            {
                this.port = value;
            }
        }

        private bool enableSsl = false;
        public bool EnableSsl
        {
            get
            {
                return enableSsl;
            }
        }

        private bool usePassive =