How do I put a Java object into a HttpSession and use it across all my packages?

Question

I am developing a Java Web Application which consists of a lot of JSPs, JSs, Servelts, while business logic is handled in POJOs.

My need is to initiate a class inside my Servlet, and set is as a global variable, and use it throughout all the packages in my application.

Now, I have defined a few global variables using

request.getSession().setAttribute("<ATTR_NAME>", <MY_OBJECT>);

But what I am lacking here is I can use the value of this attribute only inside the Servlet, or in other words, places where I have access to HttpServletRequest.

I need a solution to define a global variable, and be able to use it in all my POJOs which contain my business logic, where I may not have access to HttpServletRequest. I also do not want to pass this global variable of mine from the Servlet to all these POJOs either through Constructors or method arguments.

I have gone through a few articles which spoke about ServletContext amongst other things, but I do not get a clear picture.

Any little help is highly appreceated.

Thanks, Sriram Sridharan

possible duplicate of [How do you store Java objects in HttpSession?](http://stackoverflow.com/questions/5766521/how-do-you-store-java-objects-in-httpsession) — Abhijeet Dhumal, Jul 06 '15 at 10:09
possible duplicate of [Retrieving Web Session from a POJO Outside the Web Container](http://stackoverflow.com/questions/4764285/retrieving-web-session-from-a-pojo-outside-the-web-container) — Shekhar Khairnar, Jul 07 '15 at 04:27

score -1 · Answer 1 · answered Jul 06 '15 at 09:55

-1

Why don't you initiate a Java Bean in your base servlet and use it throughout the runtime?

public class User implements java.io.Serializable {

private String name;
private Integer age;

public String getName(){
    return this.name;
}

public void setName(String name){
    this.name = name;
}

public Integer getAge(){
    return this.age;
}

public void setAge(Integer age){
    this.age = age;
}

}

answered Jul 06 '15 at 09:55

Jeeppp

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Because they don't know how? Seems like that's the entire point of their question. – Anthony Grist Jul 06 '15 at 09:59
@AnthonyGrist I agree. The point is what do I do to make this bean visible even in places i don't have access to HttpServletRequest /HttpServletResponse? – Sriram Sridharan Jul 06 '15 at 10:02
@sriramsridharan Look out for Serialization – Jeeppp Jul 06 '15 at 10:04

score -1 · Answer 2 · edited May 23 '17 at 12:06

-1

One solution can be create a load-on-startup servlet which set the context as in the article in link access context in DAO/POJO or another solution is using filter as in link session from pojo

edited May 23 '17 at 12:06

Community

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answered Jul 06 '15 at 10:08

Shekhar Khairnar

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score -1 · Answer 3 · answered Jul 06 '15 at 10:13

If you want to use some object in application context may use some context holder (singletone) and store object in the ServletContext's attributes:

Context holder:

public class CtxHolder {
    private static ServletContext ctx;
    private static Context nCtx;

    private DSHolder() {
    }

    public static void setCtx(ServletContext ctx) {
        DSHolder.ctx = ctx;
    }

    public static ServletContext getCtx() {
        if (ctx == null) {
            throw new RuntimeException("Need to set servlet context");
        }
        return ctx;
    }
}

Then define Servlet Context Listener and invoke CtxHolder.setCtx() (from contextInitialized() method) when application starts.

Then you can get/set "global" (application's scope) attributes as:

CtxHolder.getCtx().setAttribute("key", new Object());

But remember about synchronization! Each request processes in own thread.

How do I put a Java object into a HttpSession and use it across all my packages?

3 Answers3