CODEWITHSUNDEEP
javasessionservletsthread-safety
Vishal Zanzrukia
Vishal Zanzrukia

Reputation: 4973

Is it thread safety, if I pass my HttpServletRequest, HttpServletResponse, HttpSession objects in Util methods?

Suppose I have one repeated task which is going to process HttpSession or HttpServletRequest or HttpServletResponse object. This processing may be abstract some data from HttpSession or set/get some attributes in HttpServletRequest/HttpServletResponse.

Here I am giving one example for idea. I want my current logged in UserId from session. for that I am making one Util method in one of Util classes.

public static Integer getCurrentLoggedInUserId(HttpSession session)
{
    // here I will process session object and get first User object and
    //after that I will get id from that User Object. This is one repeated task in my app.
}

second example for download file.

public static void downloadFile(HttpSrvletResponse response)
{
    // here I will set some attribues/parameters in response for download file.
}

Now my question is it thread safety to doing this? I mean is it recommended to pass session/request/response objects from controller/servlets to Util classes? If not, what is solution for these kind of repeated tasks?

Thanks in advance.

Upvotes: 1

Views: 4489

Answers (2)

GerritCap
GerritCap

Reputation: 1626

Thread safety concerns data that is shared amongst threads. For example in your case if you obtained the current user and want to store it in a set of todaysUsers, then you must protect data access to that set:

private static Set<Integer> todaysUsers = new HashSet<Integer>();

public static Integer getCurrentLoggedInUserId(HttpSession session)
{
    Integer currentUser = ......
    synchronized(todaysUsers) {
         todaysUsers.add(currentUser);
    }
    return currentUser;
}

because each thread will call the method with it's own session, this is not data sharing and thus no issue for thread safety

Upvotes: 1

Boris the Spider
Boris the Spider

Reputation: 61158

Yes. This would be thread safe if the Util class has no state.

Usually this isn't done because ideally only the Servlet should know about the request/response objects.

If you are writing a utility class that exclusively acts on the request/response objects consider writing a wrapper class that wraps, say, the request object and then acts on it.

This way you don't have thread safety concerns as you create new wrappers for each request.

Upvotes: 0

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