form1.cs

《c#技术内幕代码》

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Security;
using System.IO;
using System.Security.Permissions;

namespace CH14_3
{
	/// <summary>
	/// Summary description for Form1.
	/// </summary>
	public class Form1 : System.Windows.Forms.Form
	{
		private System.Windows.Forms.Button button1;
		private System.Windows.Forms.RadioButton radioButton1;
		private System.Windows.Forms.RadioButton radioButton2;
		private System.Windows.Forms.Button button2;
		/// <summary>
		/// Required designer variable.
		/// </summary>
		private System.ComponentModel.Container components = null;
		private Boolean fAllowWrite = true;

		public Form1()
		{
			//
			// Required for Windows Form Designer support
			//
			InitializeComponent();

			//
			// TODO: Add any constructor code after InitializeComponent call
			//
		}

		/// <summary>
		/// Clean up any resources being used.
		/// </summary>
		protected override void Dispose( bool disposing )
		{
			if( disposing )
			{
				if (components != null) 
				{
					components.Dispose();
				}
			}
			base.Dispose( disposing );
		}

		#region Windows Form Designer generated code
		/// <summary>
		/// Required method for Designer support - do not modify
		/// the contents of this method with the code editor.
		/// </summary>
		private void InitializeComponent()
		{
			this.button1 = new System.Windows.Forms.Button();
			this.radioButton1 = new System.Windows.Forms.RadioButton();
			this.radioButton2 = new System.Windows.Forms.RadioButton();
			this.button2 = new System.Windows.Forms.Button();
			this.SuspendLayout();
			// 
			// button1
			// 
			this.button1.Location = new System.Drawing.Point(48, 96);
			this.button1.Name = "button1";
			this.button1.Size = new System.Drawing.Size(192, 24);
			this.button1.TabIndex = 0;
			this.button1.Text = "Open a File";
			this.button1.Click += new System.EventHandler(this.button1_Click);
			// 
			// radioButton1
			// 
			this.radioButton1.Location = new System.Drawing.Point(40, 16);
			this.radioButton1.Name = "radioButton1";
			this.radioButton1.Size = new System.Drawing.Size(184, 24);
			this.radioButton1.TabIndex = 1;
			this.radioButton1.Text = "Allow Permission to Temp";
			this.radioButton1.CheckedChanged += new System.EventHandler(this.radioButton1_CheckedChanged);
			// 
			// radioButton2
			// 
			this.radioButton2.Location = new System.Drawing.Point(40, 56);
			this.radioButton2.Name = "radioButton2";
			this.radioButton2.Size = new System.Drawing.Size(176, 24);
			this.radioButton2.TabIndex = 2;
			this.radioButton2.Text = "Deny Permission to Temp";
			this.radioButton2.CheckedChanged += new System.EventHandler(this.radioButton2_CheckedChanged);
			// 
			// button2
			// 
			this.button2.Location = new System.Drawing.Point(96, 136);
			this.button2.Name = "button2";
			this.button2.TabIndex = 3;
			this.button2.Text = "&Close";
			this.button2.Click += new System.EventHandler(this.button2_Click);
			// 
			// Form1
			// 
			this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
			this.ClientSize = new System.Drawing.Size(292, 181);
			this.Controls.AddRange(new System.Windows.Forms.Control[] {
																		  this.button2,
																		  this.radioButton2,
																		  this.radioButton1,
																		  this.button1});
			this.Name = "Form1";
			this.Text = "Form1";
			this.ResumeLayout(false);

		}
		#endregion

		/// <summary>
		/// The main entry point for the application.
		/// </summary>
		[STAThread]
		static void Main() 
		{
			Application.Run(new Form1());
		}

		private void radioButton1_CheckedChanged(object sender, System.EventArgs e)
		{
			fAllowWrite = true;
		}

		private void radioButton2_CheckedChanged(object sender, System.EventArgs e)
		{
			fAllowWrite = false;
		}

		private void button2_Click(object sender, System.EventArgs e)
		{
			Close();
		}

		private void button1_Click(object sender, System.EventArgs e)
		{
			PermissionSet ps = new PermissionSet(System.Security.Permissions.PermissionState.None);

			ps.AddPermission(

				new FileIOPermission(FileIOPermissionAccess.Read | 

				FileIOPermissionAccess.Write | FileIOPermissionAccess.Append, 

				"c:\\temp\\temp.txt"));

			if ( fAllowWrite == false  )
			    ps.Deny();
			else
				ps.Assert();

			FileStream fs = new FileStream(@"c:\temp\temp.txt" , FileMode.OpenOrCreate, FileAccess.Write); 
			StreamWriter m_streamWriter = new StreamWriter(fs); 
  
			// Write to the file using StreamWriter class 
			m_streamWriter.BaseStream.Seek(0, SeekOrigin.End); 
			m_streamWriter.Write("Test"); 
		}
	}
}