asp.net状态保持相关知识总结

注意网站与项目的区别
多了命名空间 预编译
编码格式已响应报文为主 response.Charset="gb2312";

无状态（对象销毁 连接断开）
///////////////////////////////
viewstate 客户端 使用 一个页面使用 隐藏域自动保存值 有run="server"
禁用viewstate状态(位置可以选择 页头page指令夹为全部) EnableViewState=“false” 可以用（）工具进行状态检测
保存非单值元素 非表单元素状态
ViewState["num"] = num;（保存值）
----图片的序列和反序列化
----using System.IO;
using System.Runtime.Serialization.Formatters.Binary;
--- //定义一个变量向页面传值
protected string str="" ;
//页面加载
protected void Page_Load(object sender, EventArgs e)
{
//首次加载
if (!IsPostBack)
{
//图片保存到隐藏域中调用序列化方法
str = ImgToString();
}
//提交时
else
{
string s = Request.Form["hd"];
//调用反序列化方法形成图片
System.Drawing.Image img = StrToImg(s);
Response.ContentType = "image/jpeg";
//保存图片
img.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
}
}

private System.Drawing.Image StrToImg(string s)
{
//base64解码
byte[] buffer = Convert.FromBase64String(s);
//反序列化
using (MemoryStream ms = new MemoryStream(buffer))
{
BinaryFormatter bf = new BinaryFormatter();
System.Drawing.Image img = bf.Deserialize(ms) as System.Drawing.Image;
return img;
}
}

private string ImgToString()
{
//获取对象的路径
string path = Request.MapPath("img/IMG_4692.jpg");
//创建图片
System.Drawing.Image img = System.Drawing.Image.FromFile(path);
using (MemoryStream ms = new MemoryStream())
{
BinaryFormatter bf = new BinaryFormatter();
//把图片转化为流
bf.Serialize(ms, img);
//序列化后的对象 写入字节数组
byte[] buffer = ms.ToArray();
//把字节数组，base64编码转换成字符串
return Convert.ToBase64String(buffer);
}
}
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cookie也是保存客户端 和域名相关 和浏览器相关 数据最好加密
把少量数据保存在客户端的内存或硬盘并读取出来的一种技术 cookie位置C:\user\admin\cookie
存在硬盘时会设置cookie的时间 反之在内存上
1、普通get请求无cookie 可以通过监视观察报文
2、服务器通过响应报文头里的set-cookie向浏览器设置cookie信息
3、浏览器通过请求报文里头的cookie传递浏览器存储的cookie信息
常用于登录和保存最近浏览的商品 cookie.Expires=datetime.now.addminutes(5) 设置cookie的保存时间
1、cookie的读写
//在内存中创建对象
HttpCookie hc = new HttpCookie("test");
hc.Value = DateTime.Now.ToString();
//设置过期时间
hc.Expires = DateTime.Now.AddDays(5);
//输出 (并没有真正输出)
Response.Cookies.Add(hc);
//读cookie
HttpCookie hc=Request.Cookies["test"];
if (hc != null)
{
Response.Write(hc.Value);
}
2、cookie的删除
context.Response.ContentType = "text/plain";
//所有的cookie
int count = context.Request.Cookies.Count;
//遍历cookie
for (int i = 0; i < count; i++)
{
HttpCookie hc=context.Request.Cookies[i];
//设置过期
hc.Expires = DateTime.Now.AddDays(-1);
context.Response.Cookies.Add(hc);
}
//页面跳转
context.Response.Redirect("Login.aspx");
}
页面登录使用cookie
<登陆页>if (IsPostBack)
{
//接收传值
string name = Request.Form["txtName"];
string pwd = Request.Form["txtPwd"];
//判断
if (name == "user" && pwd == "user")
{
//创建cookie对象
HttpCookie hc = new HttpCookie("name");
hc.Value = name;//赋值 设置销毁时间
hc.Expires = DateTime.Now.AddDays(7);
//添加到集合
Response.Cookies.Add(hc);
//页面跳转
Response.Redirect("06-LoginOver.aspx");
}
}
else
{
//页面第一次加载
if (Request.Cookies["name"] != null)
{
s = Request.Cookies["name"].Value;
}
}
<登陆跳转页>
if (Request.Cookies["test"] != null)
{
Response.Write("欢迎" + Request.Cookies["test"].Value.ToString());
}
问题： 输出同名cookie浏览器会重新赋值 反之添加
设置cookie的路径hc.Path="/文件"（根目录下的文件）
cookie.Domain(域/域名)
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session服务端保存客户端的数据
在一般处理程序中必须实现接口IRequiresSessionState 添加system.web.sessionstate空间
session["name"]="";赋值 string str=session["name"].tostring();取值
销毁session.Abandon(); 对象并没有从池里销毁 Session.Clear();清空对象里的键值对
页面登录使用session sessionId 用cookie保存在浏览器的缓存内了
<页面登录>
//点击提交
if (IsPostBack)
{
string code = Request.Form["txtCode"].ToLower();
//判断验证码是否正确
//因为session有过期机制，所以先判断是否为null
if (Session["code"] !=null && code == Session["code"].ToString().ToLower())
{
//当验证码正确，移除
Session.Remove("code");

string name = Request.Form["txtName"];
string pwd = Request.Form["txtPwd"];
if (name == "admin" && pwd == "admin")
{
//记录登录成功的状态
Session["user"] = name;
Response.Redirect("08-LoginOver.aspx");
}
}
else
{
Response.Write("验证码错误");
}
}
<登陆跳转页>
//判断是否登录
if (Session["user"] == null)
{

Response.Write("<script>alert('请登录');location.href='08-Login.aspx'</script>");
}
else
{
Response.Write(Session.SessionID);
Response.Write("欢迎"+Session["user"].ToString());
}
-------验证码
<%@ WebHandler Language="C#" class="ValidateCode" %>

using System;
using System.Web;
using System.Drawing;
using System.Web.SessionState;
public class ValidateCode : IHttpHandler,IRequiresSessionState {

public void ProcessRequest(HttpContext context)
{
context.Response.ContentType = "image/jpeg";

string code = GetRndStr();
//保存在session上
context.Session["code"] = code;
using (Bitmap img = CreateImages(code, "ch"))
{
img.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
}
}

public bool IsReusable
{
get
{
return false;
}
}
/// <summary>
/// 数字随机数
/// </summary>
/// <returns></returns>
private string GetRndNum()
{
string code = string.Empty;
Random random = new Random();
for (int i = 0; i < 4; i++)
{
code += random.Next(9);
}
return code;
}
/// <summary>
/// 英文随机
/// </summary>
/// <returns></returns>
private string GetRndStr()
{
string Vchar = "A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
string[] VcArray = Vchar.Split(',');
string checkCode = string.Empty;
Random rand = new Random();
for (int i = 0; i < 4; i++)
{
int t = rand.Next(VcArray.Length);
checkCode += VcArray[t];
}
return checkCode;
}
/// <summary>
/// 中文随机
/// </summary>
/// <returns></returns>
private string GetRndCh()
{
System.Text.Encoding gb = System.Text.Encoding.Default;//获取GB2312编码页（表）
object[] bytes = CreateRegionCode(4);//生4个随机中文汉字编码
string[] str = new string[4];
System.Text.StringBuilder sb = new System.Text.StringBuilder();
for (int i = 0; i < 4; i++)
{
//根据汉字编码的字节数组解码出中文汉字
str[i] = gb.GetString((byte[])Convert.ChangeType(bytes[i], typeof(byte[])));
sb.Append(str[i].ToString());
}
return sb.ToString();
}
/// <summary>
/// 产生随机中文字符
/// </summary>
/// <param name="strlength"></param>
/// <returns></returns>
private static object[] CreateRegionCode(int strlength)
{
//定义一个字符串数组储存汉字编码的组成元素
string[] rBase = new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };
Random rnd = new Random();
object[] bytes = new object[strlength];

for (int i = 0; i < strlength; i++)
{
//区位码第1位
int r1 = rnd.Next(11, 14);
string str_r1 = rBase[r1].Trim();
//区位码第2位
rnd = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i);
int r2;
if (r1 == 13)
{
r2 = rnd.Next(0, 7);
}
else
{
r2 = rnd.Next(0, 16);
}
string str_r2 = rBase[r2].Trim();

//区位码第3位
rnd = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i);//更换随机种子
int r3 = rnd.Next(10, 16);
string str_r3 = rBase[r3].Trim();

//区位码第4位
rnd = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i);
int r4;
if (r3 == 10)
{
r4 = rnd.Next(1, 16);
}
else if (r3 == 15)
{
r4 = rnd.Next(0, 15);
}
else
{
r4 = rnd.Next(0, 16);
}
string str_r4 = rBase[r4].Trim();
//定义两个字节变量存储产生的随机汉字区位码
byte byte1 = Convert.ToByte(str_r1 + str_r2, 16);
byte byte2 = Convert.ToByte(str_r3 + str_r4, 16);

//将两个字节变量存储在字节数组中
byte[] str_r = new byte[] { byte1, byte2 };

//将产生的一个汉字的字节数组放入object数组中
bytes.SetValue(str_r, i);
}
return bytes;
}
/// <summary>
/// 画图片的背景图+干扰线
/// </summary>
/// <param name="checkCode"></param>
/// <returns></returns>
private Bitmap CreateImages(string checkCode, string type)
{
int step = 0;
if (type == "ch")
{
step = 5;//中文字符，边界值做大
}
int iwidth = (int)(checkCode.Length * (13 + step));
System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 22);
Graphics g = Graphics.FromImage(image);
g.Clear(Color.White);//清除背景色
Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };//定义随机颜色
string[] font = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };
Random rand = new Random();

for (int i = 0; i < 50; i++)
{
int x1 = rand.Next(image.Width);
int x2 = rand.Next(image.Width);
int y1 = rand.Next(image.Height);
int y2 = rand.Next(image.Height);
g.DrawLine(new Pen(Color.LightGray, 1), x1, y1, x2, y2);//根据坐标画线
}

for (int i = 0; i < checkCode.Length; i++)
{
int cindex = rand.Next(7);
int findex = rand.Next(5);

Font f = new System.Drawing.Font(font[findex], 10, System.Drawing.FontStyle.Bold);
Brush b = new System.Drawing.SolidBrush(c[cindex]);
int ii = 4;
if ((i + 1) % 2 == 0)
{
ii = 2;
}
g.DrawString(checkCode.Substring(i, 1), f, b, 3 + (i * (12 + step)), ii);

}
g.DrawRectangle(new Pen(Color.Black, 0), 0, 0, image.Width - 1, image.Height - 1);
System.IO.MemoryStream ms = new System.IO.MemoryStream();
return image;
}
<img onclick="this.src='ValidateCode.ashx?_='+Math.random()" title="看不清？" style="cursor:pointer" src="ValidateCode.ashx" /><input type="text" name="txtCode" /><br />
onclick="this.src='ValidateCode.ashx?_='+Math.random()"鼠标点击随机生成
------------------------------------------------------------------------------------
application服务端保存共享数据
应用--当前在线人数
session时间设定 <sessionState timeout="1"></sessionState>web.config
新建一个全局处理程序
protected void Application_Start(object sender, EventArgs e)
{
Application.Lock();
Application["count"] = 0;
Application.UnLock();
}

protected void Session_Start(object sender, EventArgs e)
{
Application.Lock();
Application["count"] = Convert.ToInt32(Application["count"]) + 1;
Application.UnLock();
}

protected void Application_BeginRequest(object sender, EventArgs e)
{

}

protected void Application_AuthenticateRequest(object sender, EventArgs e)
{

}

protected void Application_Error(object sender, EventArgs e)
{

}

protected void Session_End(object sender, EventArgs e)
{
Application.Lock();
Application["count"] = Convert.ToInt32(Application["count"]) - 1;
Application.UnLock();
}

protected void Application_End(object sender, EventArgs e)
{

}