| h1. Serialization |
| |
| With wicket everything is serialized. Remember this. This great framework provides support for stateful elements but there is a price - we can not use not serializable objects. Don't be afraid - we still might read them but we have to follow few rules. |
| |
| # First of all, do not assign not serializable objects to fields |
| # Do not create final variables to use in anonymous classes, it will work, but you'll get mess in logs. Look at code below |
| {code:java} |
| final Entity en = dao.find(id); # broken! |
| add(new Form<Entity>() { |
| public void onSubmit() { |
| dao.save(getModelObject()); |
| } |
| }); |
| {code} |
| As you see in marked line of this code we declared *en* variable as a final. This means that JVM will try to write reference to this variable in ObjectOutputStream, and as you might expect - you will get NotSerializableException |
| # For list views and repeaters use LoadableDetachableModels, in IDataProvider implementations/extensions remember to return LoadableDetachableModel. |
| |
| As long as you follow there rules you might sleep peacefully. In any case, when you will meet mr. NotSerializable, make own life easier and use -Dsun.io.serialization.extendedDebugInfo=true parameter to add path to not serializable element in stack trace. With these you'll get message like this: |
| |
| {code} |
| Caused by: java.io.NotSerializableException: org.apache.felix.framework.ServiceRegistrationImpl$ServiceReferenceImpl |
| - field (class "org.apache.karaf.webconsole.osgi.internal.bundle.DetailsPage$4$1", name: "val$reference", type: "interface org.osgi.framework.ServiceReference") |
| - object (class "org.apache.karaf.webconsole.osgi.internal.bundle.DetailsPage$4$1", [MarkupContainer [Component id = serviceInUseProperty]]) |
| - element of array (index: 1) |
| - array (class "[Ljava.lang.Object;", size: 2) |
| - field (class "org.apache.wicket.MarkupContainer", name: "children", type: "class java.lang.Object") |
| - object (class "org.apache.wicket.markup.html.list.ListItem", [MarkupContainer [Component id = 0]]) |
| - element of array (index: 0) |
| - array (class "[Ljava.lang.Object;", size: 7) |
| - field (class "org.apache.wicket.MarkupContainer", name: "children", type: "class java.lang.Object") |
| - object (class "org.apache.karaf.webconsole.osgi.internal.bundle.DetailsPage$4", [MarkupContainer [Component id = servicesInUse]]) |
| - element of array (index: 8) |
| - array (class "[Ljava.lang.Object;", size: 9) |
| - field (class "org.apache.wicket.MarkupContainer", name: "children", type: "class java.lang.Object") |
| - root object (class "org.apache.karaf.webconsole.osgi.internal.bundle.DetailsPage", [Page class = org.apache.karaf.webconsole.osgi.internal.bundle.DetailsPage, id = 14, version = 0]) |
| {code} |
| instead of |
| {code} |
| Caused by: java.io.NotSerializableException: org.apache.felix.framework.ServiceRegistrationImpl$ServiceReferenceImpl |
| {code} |
