Quản lý trạng thái trong ASP.NET

Cng ngh .NET.NET Technology

Lng Trn Hy HinB mn Cng ngh Phn mm

Khoa Cng Ngh Thng Tin

Trng HSP TP. H Ch Minh

Chng 3:

ASP.NET Application & State Management

Cng ngh NET 3 HIENLTH

Ni dung

Request

Response

Server

Qun l trng thi

o View state

o Session state

o Cookie

Cross-page Postback

Application


Tng quan


Request Object

Request l mt th hin ca lp HttpRequest, Browserdng Request object gi thng tin cn thit tiServer

Dng c thng tin t client gi ln (header, querystring, cookies, )

Data


Request Object (tt)

Cc thuc tnh

RequestType: tr v phng thc truyn d liu tclient n server gm 2 phng thc POST v GET

C php

valMethod=Request.RequestType


Ly d liu gi i

Request.Form("Phn_t_cn_c"): c gi tr ca mt phn t c gi theo phng thc POST.

Request.QueryString("Phn_t_cn_c"): c gi tr ca mt phn t c gi theo phng thc GET.


Request Object - POST

V d: thit k giao din nh hnh


M giao din

trang 1

username

password


Request Object - POST

V d (tt):Ly gi tr ca UserName v Password trn form

string sUser, sPass;sUser = Request.Form["txtUser"];sPass = Request.Form["txtPass"];//Xut ra mn hnh


Request Object - GET

Ly d liu t cc phn t ca form:

C php:

Nu tham s khng c gi tr th gi tr tr v ca tham s khi s dng Request.QueryString l null.

Request.QueryString[varName]



UserName:



Ti Server (file CheckUser.aspx), ly gi tr ca UserName v Password

string strUser, strPws;

strUser = Request.QueryString["txtUser"];

strPws = Request.QueryString["txtPass"];



Hoc

Tin Gio dc

Var1=Request.QueryString[CatID];//Var1=eduVar2=Request.QueryString[NewsID];//Var2=98708

Ti ReadNews.aspx mun ly gi catID and NewsID, s dng c php:


Demo Query String

To mt ng dng truy cp CSDL GameList gm:

oGameList.aspx: hin th tn tt c cc game c trong database, vi mi game to url dng querystring vi id ca game , user kch vo s m ra trang GameDetail.aspx cho php xem chi tit thng tin ca game

oGameDetail.aspx: ly id t querystring, c CSDL GameList v tr v chi tit tt c thng tin ca game.


Query String


Query String

To trang GameList.aspx

o Trang ny c control l label s hin th danh sch cc tn game.

Label: c id l lblGameList


Query String

Trang GameList.aspx khi thc thi

Danh sch cc tn game ly trong database

Hyperlink xem chi tit ca Thun Thin Kim


Query String

To trang GameDetail.aspx

o Trang ny c 4 label cha cc thng tin chi tit ca game:

Tn game: lblTenGame, nh sn xut: lblNSX, nh pht hnh: lblNPH, th loi: lblTheLoai


Query String

Phn x l ca GameDetail.aspxprotected void Page_Load(object sender, EventArgs e)

{// ly query stringstring sid = Request.QueryString["id"]; // tham s idif (sid != null) // kim tra xem tham s ny c tn ti hay khng{

// truy cap database de lay du lieustring sConn = @"server=.; database=gamelist; trusted_connection=true";SqlConnection conn = new SqlConnection(sConn); // to i tng kt nitry{

conn.Open(); // m kt nistring query = string.Format("select * from DanhMuc where ID={0}",sid);SqlCommand cmd = new SqlCommand(query, conn);SqlDataReader reader;reader = cmd.ExecuteReader(); // thc thi cu truy vn

// phn tip theo trong slide k


Query String

// tip theo ca silde trcif (reader.HasRows) // nu c d liu

{reader.Read(); // c 1 dng d liulblTenGame.Text = reader["TenGame"].ToString();lblNSX.Text = reader["NhaSanXuat"].ToString();lblNPH.Text = reader["NhaPhatHanh"].ToString();lblTheLoai.Text = reader["TheLoai"].ToString();

}reader.Close(); conn.Close(); // ng kt ni

}catch (Exception ex){

Response.Write(ex.Message); // hin th thng bo li}

} // end if (sid !=null)} // end method Page_Load


Query String

Chy demo

id = 5 l m game C Long


Response Object

Response: i tng ny c dng gi ni dung (mt xu) bt k v cho trnh duyt

Phng thc:o Response.Write() dng gi gi tr biu

thc truyn vo cho pha trnh duyt.

o Response.Redirect(a ch URL): Chuyn ti mt trang khc.

Data


Response Object (tt)

Cc phng thc

Response.Clear(): Xa vng tm

C php:

Response.Flush() dng a d liu cn trong b m pha server v cho pha trnh duyt.

Response.End(): Kt thc tin trnh x l trn Server v y d liu ti Client

Response.Clear()


Response Object

Cc thuc tnh

Buffer: c 2 gi tr true v false quy nh cch

truyn ti d liu:

o True: Hon tt cng vic v gi mt ln

o False: Thc hin xong n u th gi n


Server Object

i tng Server cung cp thng tin ca Web server chong dng, bao gm cc phng thc gip chuyn iu khingia cc trang vi nhau, ly thng tin v m li, encode,

Cc thuc tnh

o MachineName: tn server

o ScriptTimeout: thit lp thi gian x l ti a 1 file

V d:

Server.ScriptTimeout = 100s //thit lp thi gian mc nh


Server Object

Cc phng thc

MapPath(URL): nh x ng dn o thnh ng

dn vt l cho mt tp tin trn Server

o C php:

o Path l chui thc hin ng dn tng i ca tp tintrn ng dng Web

o Phng thc s tr v chui hin thc ng dn vt lca tp tin .

Server.MapPath(path)


Server Object

Transfer: gi tt c thng tin m n x l t trang

ASPX hin hnh sang trang ASPX khc. C php:

Trong , tham s path l ng dn ca tp tin ASPX

cn chuyn iu khin.

Lu :

o s dng k hiu ~ ch n ng dn tng i

o s dng k hiu .. ch n ng dn tuyt i

Server.Transfer(path)

Phn bit Server.Tranfer vs Reponse.Redirect


Server Object

HtmlEncode(str): dng m ho HTML thnhchui

C php:

Server.HTMLEncode(str)


Server Object

Khi m ho chui HTML sang chui bnh

thng nu gp cc k t nh sau s chuyn

sang k t tng ng:

o K t chuyn thnh >

o K t & chuyn thnh &

o Du i chuyn thnh "


Server Object

HtmlDecode(strcontent):gii m cc th HTML

V d:

Str = n>5

Str = Server.HtmlDecode(str); // kt qu n>5


Server Object

Phng thc URLEncode: Tng t nhphng thc HTMLEncode, phng thcURLEcode dng m ho URL thnh chui

C php:

Quy tc chuyn:

o K t khong trng chuyn thnh du +

o K t khng thuc k t ch v s s chuyn thnh s hexadecimal

Server.URLEncode(str)


Qun l trng thi


Qun l trng thi

Mi ng dng cn chia s thng tin gia cc request

ASP.NET cung cp cc c ch cho php chia s thng tin gia cc Request:

o Cc i tng qun l trng thi (State) pha client v server.

o C ch Cache


Cc i tng qun l trng thi

Client-based State

o c lu tr my Client

o Gm: ViewStates, Hidden Fields, QueryStrings, Cookies

Server-based State

o c lu tr my Server

o Gm: Session, Application


View state

Cho php lu cc kiu d liu ca .NET

Lu tr client side, trong hidden field ca trang web

Lu tr trong cc ln post back ca trang. Mt d liu khi user nhp vo URL mi

Phm vi gii hn trong mt trang web

Bo mt: mc nh trng thi insecure. Tuy nhin ta c th thit lp page directive m ha

Hn ch: lu tr s lng ln thng tin trong viewstate s lm chm thi gian response v request

Thng dng ci t thng tin c bit no ca page


View state

View state l u tin chn la u tin khi cn lu tr thng tin trong phm vi ca mt trang web

View state cng c s dng bi ASP.NET Web control, cho php cc control ny duy tr nhng thuc tnh gia cc ln postback

C th add d liu vo

view state collection

thng qua thuc tnh

Page.ViewState

int count;if (ViewState["Count"] == null)

count = 0;else

count = (int) ViewState["Count"];count += 1;

ViewState["Count"] = count;

Label1.Text = string.Format("S ln postback {0}", count);


View state

Thun li:

View state khng s dng memory trn server

View state cng khng b rng buc no (nh time out)

Tnh hung hn ch khi s dng view state

Cn thit lu tr d liu c mc nhy cm cao. View state cng c th m ha, nhng session la chn tt hn

Cn thit lu tr thng tin c s dng trong nhiu trang. Trong tnh hung ny ta s dng session, cookie hoc query string.

Cn thit lu tr thng tin ln v khng mun lm chm thi gian truyn ti, nn s dng database, cache hoc session.


Session l g?

User 1

User 2

User 3

Session: user 1Session: user 2Session: user 3


Session l g?

Khi nim phin lm vic Mi khi user request mt trang web ln u tin th

phin lm vic c to ra. Mt nhn dng phin lm vic c cp bi server Phin lm vic kt thc khi

Ngi lp trnh hy Kt thc cycle life (quy nh bi Timeout) User ng trnh duyt

Phin lm vic l cch thc trao i/chia s d liu gia cc trang web trong Web app.


Session

Cho php lu tr d liu kiu .NET

Lu tr trn b nh ca server

Thi gian sng kt thc sau mt khong thi gian nh ngha trc (thng l 20 pht, c th thay i, hoc lp trnh hy)

Phm vi ton b ng dng .NET

Tnh bo mt cao, do d liu lu tr trn server, khng bao gi chuyn cho client v mi client c client session id ring

Lu tr session vi d liu ln cng c th lm chm server, c bit nu nhiu ngi truy cp ng thi, do mi user s c bn copy session ring!


Session

Mi user s c gn mt gi tr gi l Session id, gi tr ny l duy nht

c lu tr trong non-persistent cookie cho n khi trnh duyt ng.

Session state s dng c php collection nh l view state

int count;if (Session["Count"] == null)

count = 0;else

count = (int)Session["Count"];count++;Session["Count"] = count;

int count;if (Session["Count"] == null)

count = 0;else

count = (int)Session["Count"];count++;Session["Count"] = count;


Session cu hnh

Thi gian sng ca session c th thit lp thng qua web.config (n v l pht)

Session c th lm vic m khng cn cookie

Trong trng ny Session ID lu tr trong URL

http://server/(h44a1e55c0breu552yrecobl)/page.aspxhttp://server/(h44a1e55c0breu552yrecobl)/page.aspx


Session

Phng thc

Abandon(): gii phng vng nh c dng duy tri tng Session trn Web Server ngay khi c githc hin. Nhng yu cu sau c Web server coinh l mt ngi dng mi.

Remove(SessionName): xo d liu trn bin VarSession

RemoveAll(): Xo d liu, nhng sessionID vn tn ti


Session

V d: To trang (Page) hoc User Control l Login.aspx

Thit k giao din nh sau:


Session

Khi to v Hu thng tin ng nhp ca ngi dng trong Session

void Session_Start(object sender, EventArgs e)

{

// Tng s khch ving khi c 1 phin lm vic ca user

Application["SoKhachVieng"] = (int)Application["SoKhachVieng"] + 1;

// Thit lp thi gian TimeOut cho mi phin l 30 pht

Session.Timeout = 30;

// t trng thi ban u ca user l cha ng nhp

Session["LOGIN_OK"] = false;

}


protected void btnLogin_Click(object sender, EventArgs e) {

if (Authority(txtUserName.Text, txtPassword.Text)) {

// Lu thng tin ng nhp thnh cng vo SessionSession["LOGIN_OK"] = true; // n chc nng LoginpanelLogin.Visible = false; // Hin th chc nng logout v li cho mng LblGreeting.Text = "Cho mng bn " +

txtUserName.Text + " ng nhp website!"; } else

{ // Lu thng tin ng nhp tht bi vo Session Session["LOGIN_OK"] = false;

} }


Session

protected bool Authority(string user, string pwd)

{

if (user == "admin" && pwd == "12345")

{

return true;

}

return false;

}


Cookie

L mu tin nh (dng chui) dng lu tr thng tin ngi dng trn my ca client (trong b nh hoc file text nh).

Lifetime c thit lp bi ngi lp trnh, c s dng trong nhiu trang v trong cc ln visit site

Phm vi ton b ng dng .NET

Khng bo mt, do ton b d liu c gi cho client. Cookie c th modify d dng.

Tng t nh view state, hn ch ch s dng d liu nh

Thng lu tr thng tin c nhn custom cho website.


Cookie

thit lp mt cookie: To i tng System.Net.HttpCookie To d liu dng chui Add i tng cookie vo i tng Response ca

trang web hin ti

HttpCookie cookie = new HttpCookie(Account");cookie[Username"] = Nguyen Mai Chi";Response.Cookies.Add(cookie);

HttpCookie cookie = new HttpCookie(Account");cookie[Username"] = Nguyen Mai Chi";Response.Cookies.Add(cookie);


Cookie

truy cp cookie S dng i tng Request ly cookie Kim tra xem cookie khc null? Truy cp gi tr cookie qua thuc tnh key

string str = "";HttpCookie cookie = Request.Cookies["Account"];if (cookie != null)

str = cookie["Username"];

string str = "";HttpCookie cookie = Request.Cookies["Account"];if (cookie != null)

str = cookie["Username"];


Cookie

Cookie c phn lm 2 loi Persistent cookies/permanent cookie

Lu tr trong a cng ca client cho n khi ht hn, dng cookie ny c thit lp ngy ht hn (expiration date)

Non persistent cookie/temporary cookie Khng nh ngha thi gian ht hn, cookie c lu tr

trong browser memory, kt thc khi ng trnh duyt!

Khng c s khc nhau khi s dng persistent v non persistent cookie


Cookie

Khai bo Persistent cookie

HttpCookie cookie = new HttpCookie("Account");cookie["Username"] = "Nguyen Mai Chi";cookie["email"] = [email protected]";// khai bo thi gian ht hn cho cookiecookie.Expires = DateTime.Now.AddDays(5);// add cookie vo response ca trang webResponse.Cookies.Add(cookie);

HttpCookie cookie = new HttpCookie("Account");cookie["Username"] = "Nguyen Mai Chi";cookie["email"] = [email protected]";// khai bo thi gian ht hn cho cookiecookie.Expires = DateTime.Now.AddDays(5);// add cookie vo response ca trang webResponse.Cookies.Add(cookie);


Cross-page Postback

Cross page postback l dng postback gi ti trang khc

Cc button control nh Button, ImageButton v LinkButton u c thuc tnh PostBackUrl

s dng Cross-page postback Thit lp PostBackUrl cho web form cn chuyn

n Khi user click vo button Page s c gi ti URL mi vi tt c cc gi tr

ca cc control trong trang hin thi.


Cross-page Postback

Trang cross page c th truy cp trang trc thng qua thuc tnh PreviousPage

protected void Page_Load(object sender, EventArgs e){

if (PreviousPage != null){

lblInfo.Text = "You came from " +PreviousPage.Header.Title;

}}

protected void Page_Load(object sender, EventArgs e){

if (PreviousPage != null){

lblInfo.Text = "You came from " +PreviousPage.Header.Title;

}}


Cross-page Postback

truy cp chi tit hn, cc gi tr ca control trn form, th cn phi gn tham chiu PreviousPage cho lp page tng ng

Ta c th add thuc tnh vo trang ngun v c chng trang ch.

if (PreviousPage != null) {SourcePage prevPage = PreviousPage as

SourcePage;if (prevPage != null){

lblInfo.Text = "Welcome" + prevPage.NameEntry;}

}

if (PreviousPage != null) {SourcePage prevPage = PreviousPage as

SourcePage;if (prevPage != null){

lblInfo.Text = "Welcome" + prevPage.NameEntry;}

} Tn lp ca trang source

Thuc tnh ca lp SourcePage


Cross-page Postback

Minh ha cross-page Postback

To 2 trang SendInfo.aspx: cha form nhp thng tin user TargetPage.aspx: ly thng tin t user t

SendInfo.aspx v hin th ln trnh duyt.


Cross-page Postback

M t control ca trang SendInfo.aspx

Id control Kiu control Thuc tnh Din gii

txtUsername TextBox Nhp tn user

txtEmail TextBox Nhp a ch email

txtCompany TextBox Nhp tn cng ty

btnPostInfo Button PostBackUrl = ~/TargetPage.aspx

Button thc thi thao tc Cross Page Postback


Cross-page Postback

Khai bo thuc tnh PostBackUrl cho button btnPostInfo

Khai bo URL cho PostBackUrl


Cross-page Postback

M t trang TargetPage.aspx Ly thng tin t SendInfo.aspx v hin th ra

trnh duyt

Id control Kiu control Thuc tnh Din gii

lblUsername Label - Hin th tn user

lblEmail Label - Hin th email

lblCompany Label - Hin th cng ty


Cross-page Postback

Phn x l ca TargetPage ly thng tin t SourcPage.aspx

protected void Page_Load(object sender, EventArgs e) {// ly thng tin t previous pageif (PreviousPage != null) {

// bin i tng source tham chiu n previous pageSendInfo source = PreviousPage as SendInfo;

// ly cc control ca previous page (SourcePage.aspx)TextBox username = (TextBox) source.FindControl("txtUsername");TextBox email = (TextBox) source.FindControl("txtEmail");TextBox company = (TextBox)source.FindControl("txtCompany");

// gn thng tin cho cc labellblUsername.Text = username.Text;lblEmail.Text = email.Text;lblCompany.Text = company.Text;

} // end if} // end method Page_Load

ID ca control trong SendInfo.aspx

SendInfo l class page ca SendInfo.aspx


Application

i tng Application c s dng qun l

tt c cc thng tin ca mt ng dng web, bao

gm cc file, trang web, s kin, module v code

trong th mc web o(virtual directory) v cc th

mc con ca n.

Application chia s thng, ngha l mt Application

sau khi khi to th mi ngi s dng c th truy

cp i tng ny.


Application vs Session

Application:

o Chia s d liu cho tt c ngi dng ca mt ng dng (d liu ton cc, a ngi dng)

Session:

o Chia s d liu cho nhiu Web Form trong cng mt Session

o Ch c Session hin hnh mi c kh nng truy cp thng tin Session ca chnh n.


S kin Application v Session

Application_Start: Ngi dng u tin ving thm 1 trang web trong ng dng web c gi.

Application_End: Khi ng dng web kt thc (khng c ngi dng no m trang web ca ng dng)

Application_Error: Xy ra khi c li trong ng dng

Session_Start: Mt ngi dng mi, gh thm 1 trang web ca ng dng

Session_End: Ngi dng ng trnh duyt hoc sau mt khong thi gian timeout khng request ln ng dng


Application

Khi to:

i tng Application c to khi client yu cu bt k trang no trong ng dng

Application.Lock();

Application[TenBien] = Value ;

Application.UnLock();


Application

Ly gi tr:

= Application[tn bin];string s = (string) Application[chuoi] ;

int count = (int) Application[count] ;


V d dng Application

c s lt truy cp, s ngi online


THE END

Documents

Quản lý trạng thái trong ASP.NET