@FacesComponent中的@Inject-ed值为null [英] @Inject-ed value null in @FacesComponent

问题描述

我的印象是CDI不支持具有 @javax.faces.component.FacesComponent 的类。这是真的？

I have the impression that CDI is not working with classes that have a @javax.faces.component.FacesComponent. Is this true?

这是我的例子，不起作用。 MyInjectableClass 用于代码中注入不成问题的其他位置，因此它必须是 @FacesComponent 我认为是注释。

Here's my example, that doesn't work. The MyInjectableClass is used at other points in the code where injection is not a problem, so it must be about the @FacesComponent annotation I think.

我要注入的课程：

@Named
@Stateful
public class MyInjectableClass implements Serializable {

    private static final long serialVersionUID = 4556482219775071397L;
}

使用该类的组件;

@FacesComponent(value = "mycomponents.mytag")
public class MyComponent extends UIComponentBase implements Serializable {

    private static final long serialVersionUID = -5656806814384095309L;

    @Inject
    protected MyInjectableClass injectedInstance;


    @Override
    public void encodeBegin(FacesContext context) throws IOException {
        /* injectedInstance is null here */
    }
}

推荐答案

不幸的是，即使对于JSF 2.2 @FacesComponent ， @FacesValidator 和 @FacesConverter 不是有效的注射目标（读取< a href =http://jdevelopment.nl/jsf-22/ =nofollow noreferrer>在JSF 2.2中有什么新功能？？由Arjan Tijms提供更多细节）。正如Arjan所指出的那样：

Unfortunately, even for JSF 2.2 @FacesComponent, @FacesValidator and @FacesConverter are not valid injection targets (read What's new in JSF 2.2? by Arjan Tijms for more details). As Arjan points out:

尽管如此，JSF 2.3可能会考虑这些因素。

It’s likely that those will be taken into consideration for JSF 2.3 though.

你现在可以做些什么？好吧，你基本上有两个选择：

What can you do for now? Well, you've got basically two choices:

1. 处理通过查找进行CDI注入，或切换到EJB并执行更简单的EJB查找;


2. 使用 @Named 而不是 @FacesComponent ， @Inject 组件的方式与在faces-config.xml中注册您的组件。由于UI组件实例是通过JSF Application＃createComponent（）创建的，而不是通过CDI创建的，因此您也需要一个自定义的应用程序实现（就像OmniFaces对那些转换器/验证器一样）。

1. Handle CDI injection via lookup, or switch to EJB and do the simpler EJB lookup;
2. Annotate tour class with @Named instead of @FacesComponent, @Inject the component the way you did and register your component in faces-config.xml. As the UI component instance is created via JSF Application#createComponent(), not via CDI you will also need a custom Application implementation as well (exactly like OmniFaces has for those converters/validators).

顺便说一下，你有两个问题就是你到目前为止所得到的：（1）的意思@Named @状态当前者来自CDI世界而后者来自EJB世界时（2）你确定你打算将状态保存在基本上每次请求都重新创建的faces组件中吗？

And, by the way, you've got two issues with what you've got this far: (1) what is meant by @Named @Stateful when the former is from a CDI world and the latter is from EJB world and (2) are you sure you intend to keep state in a faces component that's basically recreated on every request?

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