Built-in objects (Session, application, ViewState)

Built-in objects: for cross-page values and state retention. →http of the non-state of the

"4,"Session:
Each computer accesses the server, it will be a separate set of Session,key values are the same, but the content is not the same

All of the above is the same as cookies.

Not the same:
1, the session save location is saved on the server
2, the session does not have a lasting, its preservation period is 20 minutes

Focus: Do not abuse the session, do not use, misuse may cause server content overflow, do not cause waste of resources, because in-memory data extraction and interaction is the fastest

Assignment: session["key"] = value;
Value: String a = session["key"];
Clear: session["key"]=null;

Denglu.aspx Interface:

 protected voidPage_Load (Objectsender, EventArgs e) {Button1.Click+=button1_click; }    voidButton1_Click (Objectsender, EventArgs e) {        stringUname =TextBox1.Text; session["User"] = Uname;//Assign Valuesession["Zhi1"] = TextBox3.Text;//send a value again .Response.Redirect ("xianshi.aspx"); }

Xianshi.aspx Interface:

 protected voidPage_Load (Objectsender, EventArgs e) {        if(session["User"] ==NULL)//Take value{Response.Redirect ("denglu.aspx"); }        Else{Label1.Text="Hello,"+session["User"]; //When you pass the second value, the display is finished. Closelabel1.text+=session["Zhi1"]; session["Zhi1"]=NULL;//do not need to hold when        }    }

"5,"Application:

Global objects
application["Key"] is all the user gets the value of this key is the same
Without a save cycle, it will always be saved
Where it's usually used, the version number

Assignment value: application["key"]= value;
Value: Application.get ("key");

Denglu.aspx interface: application["Banben"] = "V1.3";

Xianshi.aspx Interface: Response.Write ("Current version number:" +application.get("Banben"));

"6,"ViewState:

Understand the case and record the content information of the previous page.

1) The session value is stored in the server memory, then, it is certain that a large number of use of the session will result in a heavier server burden. Instead of ViewState server resources by simply depositing data into a page-hidden control, we can save variables and objects that require the server to "remember" into viewstate. Sesson should only be applied to variables and object stores that require cross-pages and are related to each access user.

ViewState is not able to store all of the. NET type data, it only supports string, Integer, Boolean, Array, ArrayList, Hashtable, and some types of customizations.

Everything has two sides, using ViewState will increase the output of the page HTML, the use of more bandwidth, which we need to consider carefully. In addition, since all viewstate are stored in a hidden domain, the user can easily view the source code to see this base64 encoded value. Then you can get the object and variable values that you store in the conversion.

Built-in objects (Session, application, ViewState)