JavaSerializer - 序列化对象时出错 -> wicket

Question

我有一个带有选项卡的主页 (BasePage)，一切正常，我的代码功能没有任何问题。但是这个异常让我很烦，我想摆脱它。我看了这个

Error serializing object class - when running Wicket and GAE

还有这个

Wicket: how to get rid of WicketNotSerializableException?

但我没能解决我的问题。谁能帮帮我？

public class BasePage extends WebPage {
    public static final String PATH = "base";

    public BasePage() {
        final List tabs = new ArrayList<>();

        //add Search Item Tab
        tabs.add(new AbstractTab(new Model<>("Search Item")) {
            @Override
            public WebMarkupContainer getPanel(String s) {
                return new SearchItem(s);
            }
        });

        //add Search Domain Tab
        tabs.add(new AbstractTab(new Model<>("Search Domain")) {
            @Override
            public WebMarkupContainer getPanel(String s) {
                return new SearchDomain(s);
            }
        });

        AjaxTabbedPanel ajaxTabbedPanel = new AjaxTabbedPanel("tabs", tabs);

        add(new AjaxTabbedPanel("tabs", tabs));
    }
}

堆栈跟踪：

2015-08-28 11:39:48,456 [http-bio-8080-exec-12] ERROR org.apache.wicket.serialize.java.JavaSerializer - Error serializing object class com.ui.homepage.BasePage [object=[Page class = com.ui.homepage.BasePage, id = 0, render count = 1]]
org.apache.wicket.core.util.objects.checker.CheckingObjectOutputStream$ObjectCheckException: The object type is not Serializable!
A problem occurred while checking object with type: com.persistence.RequestEntityDAOExtra
Field hierarchy is:
  0 [class=com.ui.homepage.BasePage, path=0]
    private java.lang.Object org.apache.wicket.MarkupContainer.children [class=org.apache.wicket.extensions.ajax.markup.html.tabs.AjaxTabbedPanel, path=0:tabs]
      private java.lang.Object org.apache.wicket.MarkupContainer.children [class=[Ljava.lang.Object;]
        private org.apache.wicket.markup.html.link.PopupSettings org.apache.wicket.markup.html.link.Link.popupSettings[1] [class=com.searchpages.SearchItem, path=0:tabs:panel]
          private java.lang.Object org.apache.wicket.MarkupContainer.children [class=[Ljava.lang.Object;]
            private java.lang.Object org.apache.wicket.MarkupContainer.children[1] [class=org.apache.wicket.markup.html.form.Form, path=0:tabs:panel:searchForm]
              private java.lang.Object org.apache.wicket.MarkupContainer.children [class=[Ljava.lang.Object;]
                private java.lang.Object org.apache.wicket.MarkupContainer.children[0] [class=org.apache.wicket.markup.html.WebMarkupContainer, path=0:tabs:panel:searchForm:searchInput]
                  private java.lang.Object org.apache.wicket.MarkupContainer.children [class=[Ljava.lang.Object;]
                    private java.lang.Object org.apache.wicket.MarkupContainer.children[0] [class=org.apache.wicket.extensions.ajax.markup.html.autocomplete.AutoCompleteTextField, path=0:tabs:panel:searchForm:searchInput:callerId]
                      final com.persistence.RequestEntityDAOExtra com.ui.searchpages.SearchItem.val$requestEntityDAOExtra [class=com.persistence.RequestEntityDAOExtra] <----- field that is causing the problem

更新：我发现了问题，但我不明白为什么会这样

之前：

final RequestEntityDAOExtra requestEntityDAOExtra =
        ((MyApp) getApplication()).getRequestEntityDAOExtra();

//callerId input
final AutoCompleteTextField<String> callerInput = new AutoCompleteTextField<String>("callerId", new Model<String>(),
        autoCompleteSettings) {
    @Override
    protected Iterator getChoices(String callerId) {
        return requestEntityDAOExtra.getEntitiesByCallerId(callerId).iterator();
    }
};

之后：

final AutoCompleteTextField<String> callerInput = new AutoCompleteTextField<String>("callerId", new Model<String>(),
        autoCompleteSettings) {
    @Override
    protected Iterator getChoices(String callerId) {
        final RequestEntityDAOExtra requestEntityDAOExtra =
                ((MyApp) getApplication()).getRequestEntityDAOExtra();
        return requestEntityDAOExtra.getEntitiesByCallerId(callerId).iterator();
    }
};

如果我在方法中声明我的 dao 对象，异常将不再存在。但是为什么？

Answer 1

嗯，好像 RequestEntityDAOExtra 不是 Serializable。我真的不能说为什么不或者是否应该 Serializable 因为它在很大程度上取决于您的应用程序。

在您的第一个案例中，您声明：

final RequestEntityDAOExtra requestEntityDAOExtra =
    ((MyApp) getApplication()).getRequestEntityDAOExtra();

在序列化期间，这将被视为与任何成员变量相同，因为每当执行匿名内部 class 时都需要恢复它。我的建议是在 Wicket 上下文中将变量声明为 final 时要非常小心。对于我的项目，我只允许将 IModel 的实现声明为最终的（显然加上任何 Wicket 组件）。

您的第二种方法有效，因为 RequestEntityDAOExtra 不会与 Panel 序列化，而是每次从您的 Application 重新请求。

JavaSerializer - 序列化对象时出错 -> wicket

JavaSerializer - Error serializing object -> wicket

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