Thanks.
But in my example , I cannot modify BufferedImage (to add a no-arg
constructor)
What should I do if I want to output a BufferedImage (and make back button
work) ?
2013/5/14 Jonas <barney...@gmail.com>
> This could only work if BufferedImage itself had a no-arg constructor.
> It is it the first non-serializable class in the hierarchy that needs to
> have it,
> not the first serializable one, like in your example.
> Besides, you would still lose all data stored in the BufferedImage's fields
> (i.e.
> the image stored in it).
>
>
> On Mon, May 13, 2013 at 7:15 PM, smallufo <small...@gmail.com> wrote:
>
> > Today I encountered one famous deserialization problem :
> > InvalidClassException : no valid constructor
> >
> > I googled and found some solution , but all are in-vain.
> > The solution says the first non-serializable super class should define a
> > no-arg constructor.
> >
> > But I try to define a no-arg constructor to EACH class of the HIERARCHY ,
> > and EACH class implements Serializable... (which is not necessary , but I
> > want to make it simple , to pinpoint the problem)
> >
> > My base class is an abstract class extends BufferedImage (java 2D)
> > while BufferedImage is not Serializable
> > So I make my abstract class implements Serializable and define a no-arg
> > default constructor.
> >
> > The total hierarchy is :
> > public abstract class AbstractChart extends BufferedImage implements
> > Serializable {
> > public AbstractChart() { // I try to remove this constructor ,
> > but in vain
> > super(0 , 0, TYPE_INT_ARGB);
> > }
> > }
> >
> > and first child class :
> >
> > public class ChildChart extends AbstractChart implements Serializable {
> > public ChildChart() {
> > super(); // or not calling super()
> > }
> > }
> >
> > and the grandson class :
> >
> > public class GrandsonChart extends ChildChart implements Serializable {
> > public GrandsonChart() {
> > super(); // or not calling super()
> > }
> > }
> >
> > No matter I calls super() in ChildChart or GrandsonChart ,
> >
> > Caused by: java.io.InvalidClassException: foobar.GrandsonChart; no valid
> > constructor
> >
> > It happens when I click a button ,use ajax to paint this GrandsonChart ,
> > and click another page , and use browser back .
> > The browser will be redirected to /context/wicket/page?xxx (The error
> page)
> > The screen shows :
> > Could not deserialize object using:
> > class
> >
> >
> org.apache.wicket.serialize.java.JavaSerializer$ClassResolverObjectInputStream
> >
> > and in the console log , I can see this InvalidClassException is thrown.
> >
> > Any way to solve this problem ?
> > (I've already added default no-arg constructor , and make each class
> > implements Serializable , but still not working )
> >
> > environment :
> > Wicket version : 6.7
> > Resin 4.0.25
> > Java HotSpot(TM) 64-Bit Server VM 20.4-b02-402, 64, mixed mode, Apple Inc
> > (It happens on Linux JDK too)
> >
>
