小窗口依赖注入与实现IComponentInstantiationListener的类一起工作。每当组件被实例化时调用这些应用程序级别的监听器。这是用于依赖注入组件的钩子。

模型类没有这样的机制。任何模型都可以直接实现IModel，所以没有抽象的基类可以调用监听器，不像Component。

我为我注入的模型使用了以下基类（Wicket 1.5 ）：

  public abstract class InjectedDetachableModel< T>扩展LoadableDetachableModel< T> {

 public InjectedDetachableModel（）{
 Injector.get（）。inject（this）; 
} 

 public InjectedDetachableModel（T a_entity）{
 super（a_entity）; 
 Injector.get（）。inject（this）; 
} 
} 
 

修改：
从 Wicket 1.5迁移指南获取的1.4和1.5之间的相关差异摘要：

Wicket 1.4

  @Override 
 protected void init （）
 {
 //初始化Spring 
 addComponentInstantiationListener（new SpringComponentInjector（this，applicationContext））; 
} 
 

和

  InjectorHolder.getInjector（）。inject（Object object）
 

Wicket 1.5：

  @Override 
 protected void init（）
 {
 // initialize Spring 
 getComponentInstantiationListeners（）。add（new SpringComponentInjector（this，applicationContext））
} 
 

和

  Injector.get（）。inject（Object object）
 / pre> 
In a custom Wicket class, not unlike the following, I'm using a service bean which should be injected by Spring, as defined with the SpringBean annotation (from the wicket-spring project).
public class ReportExportFileModel extends AbstractReadOnlyModel<File> {

    @SpringBean(name = "reportService")
    ReportService reportService;

    ReportDto reportDto;

    ReportExportFileModel(ReportDto reportDto) {
        this.reportDto = reportDto;
    }

    @Override
    public File getObject() {
        try {
            return reportService.generatePentahoReport(reportDto);
        } catch (ReportGenerationException e) {
           // ...
        }
    }
}
However, this doesn't work: reportService.generatePentahoReport() fails with NullPointerException, because the bean has not been injected by Spring for some reason. 

Curiously, I've used the exact same Model code as anonymous inner class on a Wicket Page, and there was no problem there.

How can I fix this?
The wicket dependency-injection works with classes implementing IComponentInstantiationListener. These application-level listeners are called whenever a Component is instantiated. This is the hook used for dependency injection of components.

The model classes do not have such a mechanism in place. Any model can directly implement IModel so there is no abstract base class which can call the listeners, unlike Component.

I use the following base class for my injected models (Wicket 1.5):
public abstract class InjectedDetachableModel<T> extends LoadableDetachableModel<T> {

    public InjectedDetachableModel() {
        Injector.get().inject(this);
    }

    public InjectedDetachableModel(T a_entity) {
        super(a_entity);
        Injector.get().inject(this);
    }
}
Edit:
Summary of relevant differences between 1.4 and 1.5, taken from Wicket 1.5 migration guide:

Wicket 1.4

@Override
protected void init()
{
    // initialize Spring
    addComponentInstantiationListener(new SpringComponentInjector(this, applicationContext));
}
and
InjectorHolder.getInjector().inject(Object object)


Wicket 1.5:

@Override
protected void init()
{
    // initialize Spring
    getComponentInstantiationListeners().add(new SpringComponentInjector(this, applicationContext))
}
and
Injector.get().inject(Object object)