public class A{
    public static int a = 0;
}

public class B{
    static{
        A.a = 123;
    }
}

public class C{
    public static void main(String args[]){
        B b=new B();
        System.out.println(A.a);
    }
}

------解决方案--------------------

你应该看的是ServletContext set 和 get attribute ...