C# 超简单的入门级示例<实例学习>

【实例截图】

【核心代码】

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Net.Mail;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
	public partial class Form1 : Form
	{
		public Form1()
		{
			InitializeComponent();
		}
		/// <summary>  
		/// 生成缩略图  
		/// </summary>  
		/// <param name="maxWidth">生成的缩略图最大宽度</param>  
		/// <param name="maxHeight">生成的缩略图最大高度</param>  
		/// <param name="imgFileStream">图片文件流对象</param>  
		/// <param name="savePath">文件保存路径</param>  
		/// <param name="imgFormat">生成图片的格式</param>  
		public void GenerateThumbnail(int maxWidth, int maxHeight, System.IO.Stream imgFileStream, string savePath,
																		 System.Drawing.Imaging.ImageFormat imgFormat)
		{
			using (var img = System.Drawing.Image.FromStream(imgFileStream))
			{
				var sourceWidth = img.Width;
				var sourceHeight = img.Height;

				var thumbWidth = sourceWidth; //要生成的缩略图的宽度  
				var thumbHeight = sourceHeight; //要生成的缩略图的高度  

				//计算生成图片的高度和宽度  
				if (sourceWidth > maxWidth || sourceHeight > maxHeight)
				{
					var rateWidth = (double)sourceWidth / maxWidth;
					var rateHeight = (double)sourceHeight / maxHeight;

					if (rateWidth > rateHeight)
					{
						thumbWidth = maxWidth;
						thumbHeight = (int)Math.Round(sourceHeight / rateWidth);
					}
					else
					{
						thumbWidth = (int)Math.Round(sourceWidth / rateHeight);
						thumbHeight = maxHeight;
					}
				}

				using (var bmp = new System.Drawing.Bitmap(thumbWidth, thumbHeight))
				{
					//从Bitmap创建一个System.Drawing.Graphics对象，用来绘制高质量的缩小图。  
					using (var gr = System.Drawing.Graphics.FromImage(bmp))
					{
						//设置 System.Drawing.Graphics对象的SmoothingMode属性为HighQuality  
						gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
						//下面这个也设成高质量  
						gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
						//下面这个设成High  
						gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

						//把原始图像绘制成上面所设置宽高的缩小图  
						var rectDestination = new System.Drawing.Rectangle(0, 0, thumbWidth, thumbHeight);
						gr.DrawImage(img, rectDestination, 0, 0, sourceWidth, sourceHeight,
												 System.Drawing.GraphicsUnit.Pixel);
						//保存图像  
						bmp.Save(savePath, imgFormat);
					}
				}
			}
		}

		private void button1_Click(object sender, EventArgs e)
		{
			//SendMailUseZj();
		SendSMTPEMail("smtp.qq.com", "2644783865@qq.com", "362524199005045535a3370501", "542860275@qq.com", "3625", "用asp.net发送邮件，用qq的smtp.qq.com服务器，测试成功");
		}
		//public void SendMailUseZj()
		//{
		//		System.Net.Mail.MailMessage msg = new System.Net.Mail.MailMessage();

		//		//msg.To.Add("lcvfb@qq.com");
		//		msg.To.Add("这里填发给地址如WQER@qq.com");
        
		//		// msg.To.Add("b@b.com");
		//		//可以发送给多人 
       
		//		//msg.CC.Add("c@c.com");
		//		//可以抄送给多人 
        
		//		msg.From = new MailAddress("asdasd@126.com", "SFADSXCVXXV", System.Text.Encoding.UTF8);/* 上面3个参数分别是发件人地址（可以随便写），发件人姓名，编码*/
		//		msg.Subject = "aaaaa" ;//邮件标题 
		//		msg.SubjectEncoding = System.Text.Encoding.UTF8;//邮件标题编码 
		//		msg.Body = "adsssssssss";//邮件内容 
		//		msg.BodyEncoding = System.Text.Encoding.UTF8;//邮件内容编码 
		//		msg.IsBodyHtml =true;//是否是HTML邮件 
		//		//msg.Priority = MailPriority.High;//邮件优先级 

		//		SmtpClient client = new SmtpClient();
		//		client.Credentials = new System.Net.NetworkCredential("AAAAAAAA@126.com", "77777777"); //发送的邮箱账号密码。这肯定得写你自己的,我用的126
		//		client.Host = "smtp.126.com";
		//		object userState = msg;
		//		try
		//		{
		//				//client.SendAsync(msg, userState);
		//				client.Send(msg);
		//				Label1.Text = "发送成功！！";
		//		}
		//		catch (System.Net.Mail.SmtpException ex)
		//		{
		//			 Label1.Text = "发送失败!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!";//前台的标签，不用说了吧
		//		}
		//}
		public void SendSMTPEMail(string strSmtpServer, string strFrom, string strFromPass, string strto, string strSubject, string strBody)
		{
			try
			{
				System.Net.Mail.SmtpClient client = new SmtpClient(strSmtpServer);
				client.UseDefaultCredentials = false;
				client.Credentials = new System.Net.NetworkCredential(strFrom, strFromPass);
				client.DeliveryMethod = SmtpDeliveryMethod.Network;
				System.Net.Mail.MailMessage message = new MailMessage(strFrom, strto, strSubject, strBody);
				message.BodyEncoding = System.Text.Encoding.UTF8;
				message.IsBodyHtml = true;
				client.Send(message);
			}
				catch (Exception ex)
			{
				throw ex;
				}
			finally
			{

			}
			
		}
		//第一个参数是邮箱服务器
		//第二个参数发件人的帐号
		//第三个参数发件人密码
		//第四个参数收件人帐号
		//第五个参数主题
		//第六个参数内容.
	}
}