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Most people do not understand the knowledge points of this article "session object and method instance Analysis in java", so the editor summarizes the following contents, detailed contents, clear steps, and has a certain reference value. I hope you can get something after reading this article. Let's take a look at this "session object and method instance Analysis in java" article.

The session object is used to record the access status of each client within the scope of the session, so as to track the operational status of each client, and the information stored in the session can obtain valid data for these sessions when the browser makes subsequent requests.

You can use the session object (the built-in object of jsp) directly in the jsp page, or you can go back to the session object through pageContext.getSession () or request.getSession.

Session can save users' information and implement functions such as shopping carts.

HTTP protocol is a stateless protocol, the client sends the request request to the server, and then the server returns the response response, the connection is closed, and the server does not save the information about the connection, so the server has no previous connection information in the next connection, so it is impossible to judge that this connection and the last connection are the same customer information. Therefore, the session must be used to record the connection information.

From the time the client opens the browser to connect to the server, to the time the client closes the browser and leaves the server, it is called a session. When a client accesses the server, it may repeatedly connect to several pages on the server, refresh a page repeatedly, or constantly submit information to a page, etc., the server should know in some way that this is the same customer, and a session object is needed.

Session works as follows:

1. When a client visits a page of the server for the first time, the server assigns a session object to the user, assigns a unique ID to the session, and sends the ID to the client and writes it to the cookie, which enables the client to establish an one-to-one corresponding relationship with the server's session.

2. When the client continues to access other resources on the server side, the server will no longer assign a new session object to the client until the client browser closes, times out, or calls the invalidate () method of session to invalidate it, and the session between the client and the server ends.

3. When the customer reopens the browser to access the website, the server will reassign a session object to the customer and reassign the sessionID.

The session object is mainly used for property manipulation and session management. The common methods are as follows:

1. Public void setAttribute (String name,String value) sets the value of the property with the specified name and adds it to the scope of the session session, and if the property exists within the session scope, change the value of the property.

2. Public Object getAttribute (String name) gets the value of the property with the specified name within the scope of the session, returns the value type object, and returns null if the attribute does not exist.

3. Public void removeAttribute (String name), delete the session attribute with the specified name. If the attribute does not exist, an exception occurs.

4. Public void invalidate () to invalidate session. The current session can be invalidated immediately, and all objects stored in the original session can no longer be accessed.

5. Public String getId () to get the current session ID. Each session has a unique label on the server side that indicates that the only data sent to the browser by the sessionID,session object is sessionID, which is typically stored in cookie.

6. Public void setMaxInactiveInterval (int interval) sets the maximum duration of the session in seconds, and a negative number indicates that the session never expires.

7. Public int getMaxInActiveInterval () to get the maximum duration of the session.

8. You can use the getCreationTime () and getLastAccessedTime () methods of the session object to get the time when the session was created and the last time it was accessed, but the return value is milliseconds. You generally need to use the following conversion to get the specific date and time.

Date creationTime = new Date (session.getCreationTime ()); Date accessedTime = new Date (session.getLastAccessedTime ()); session object method session ID:

Whether it is a new session:

Set and get property object: user name =

Session creation time:

Last visit time:

Session duration (s):

Modified session duration (s):

Several methods commonly used to get session HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes ()). GetRequest () in 1.spring mvc

(1)

ActionContext context = ActionContext.getContext (); Map request = (Map) context.get ("request"); Map session = context.getSession (); Map application = context.getApplication ()

(2)

ActionContext actionContext = ActionContext.getContext (); HttpServletRequest request = (HttpServletRequest) actionContext.get (ServletActionContext.HTTP_REQUEST); HttpSession session = request.getSession (); ServletContext context = (ServletContext) actionContext.get (ServletActionContext.SERVLET_CONTEXT); 3. Get HttpServletRequest request = ServletActionContext.getRequest (); HttpSession session = request.getSession () through ServletActionContext; the above is about "instance analysis of session objects and methods in java". I believe you all have some understanding. I hope the content shared by the editor will be helpful to you. If you want to know more about the relevant knowledge, please pay attention to the industry information channel.

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