Re: Serialization

[Ronald Klop]

What does ddm2 look like? Does it have a reference to the jsp object?

Ronald.


Op maandag, 4 oktober 2010 15:10 schreef Wolfgang Orthuber 
<orthu...@kfo-zmk.uni-kiel.de>:

Hello,

my tomcat version is 5.5.17, my question concerns serialization of objects, 
below is a code section for writing and reading an object. If I call write 
immediately before read:
d5.write();
d5.read();

then all works fine, but if I use only read (on an formerly written file) with 
the same code included in another program module, I got the exceptions like 
this:
java.lang.ClassCastException: org.apache.jsp.w.w4a_jsp$1ddm2 cannot be cast to 
org.apache.jsp.w.w4b_jsp$1ddm2

in which w4a.jsp and w4b.jsp are two different modules which include the same 
code for read and write. The name of the program module is stored in the 
serialized object, but the name of the program module does not matter, because 
both modules include the same code.

Do you know a simple solution which avoids the exception?

Wolfgang



The code section with read and write:


class dm5t implements Serializable {
     public ArrayList<ddm2>    v5;

     public dm5t () {  v5 = new ArrayList<ddm2> (); }

     public String topicpath(){return 
getServletContext().getRealPath("")+"/tp/";}

     public synchronized boolean write () {
         String fn=fntopics;
         boolean ok=true;
         try {
             String spath = topicpath();

             FileOutputStream    fs = new FileOutputStream (spath+fn);
             ObjectOutputStream    os = new ObjectOutputStream    (fs);
             os.writeObject (v5);
             os.close ();}
         catch (IOException e) {ok=false;} return ok;}

     public synchronized boolean    read () {
         String fn=fntopics;
         boolean ok=true;
         ArrayList<ddm2>    v5tmp=null;
         try {
             String spath = topicpath();

             FileInputStream        fs = new FileInputStream (spath+fn);
             ObjectInputStream    os = new ObjectInputStream    (fs);

             v5tmp = (ArrayList<ddm2>) os.readObject ();
             os.close ();

         } catch (IOException e) {ok=false;}
         catch (ClassNotFoundException e) {ok=false;}
         if (ok)    if (v5tmp != null) v5=v5tmp;
         return ok;}
}


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