如何发送参数以用于支持bean的@PostConstruct方法? [英] How can i send a parameter to be used in the @PostConstruct method of a backing bean?

问题描述

我需要预加载一些数据，以便在页面加载时显示.初始化步骤是在@PostConstruct注释的方法上执行的，但是现在我需要使用参数才能获取数据.

I need to preload some data to be displayed when the page loads. The initialization steps are performed on a @PostConstruct-annotated method but now i need to use a parameter in order to get the data.

我要做什么:

@PostConstruct
public void init()
{
   List data = getDataFromDB(parameter) /*Need to read a parameter created somewhere else*/
}

有没有办法做到这一点?

Is there a way to achieve this?

预先感谢

推荐答案

很难说出在其他地方设置的参数"的含义.我将假设其他地方"的意思是通过HTTP从浏览器发送".在这种情况下，您应该在托管bean中创建一个标准属性，并:

It's kind of hard to say what you mean by "a parameter set somewhere else". I will assume that "somewhere else" means "sent from browser by HTTP". In such case you should create a standard property in your managed bean and:

• 在JSF 2.0中，您可以使用@ManagedProperty(#{param.nameOfParameterToRead}"))对其进行注释
• 在JSF 1.2及更低版本中-在bean描述(faces-config.xml)中使用托管属性元素.

赞:

    @ManagedBean
    @RequestScoped
    class MyManagedBean {

   @ManagedProperty("#{param.id}")
   public Integer id;

   @PostConstruct
   public void init(){
     data = getDataFromDB(id)
   }



// setters and getters (mandatory, even though annotation is on an attribute!!!)


}

小心:注入属性不使用JSF转换器，因此最好注入字符串并在自己的代码中进行转换.

Careful: injecting properties does not use JSF converters, so it is best to inject strings and take care of conversion in your own code.

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