非请求范围Bean中的@ManagedProperty（value ="＃{param.id}"）

问题描述

我需要将一个参数（POST）传递给@managedBean，我使用了这样的托管属性：

  @ManagedProperty （value =＃{param.id}）
 private int id; 
  

Bean的范围是ViewScope

我该怎么办？

arjan看看：

我的页面：




Facelet标题

 < form method =postaction =faces / index.xhtml> 
< input name =idvalue =4/> 
< input type =submitvalue =submit/> 
< / form> 
 
< h：form> 
< h：commandLink value =clickaction =index> 
< f：param id =idname =idvalue =20/> 
< / h：commandLink> 
< / h：form> 
  

解决方案

两种方式：

1. 使bean请求作用域并将视图范围注入另一个 @ManagedProperty 。

     @ManagedBean 
    @RequestScoped 
    public class RequestBean {
    
    @ManagedProperty（value =＃{param.id}）
    private Integer id; 
    
    @ManagedProperty（value =＃{viewBean}）
    private ViewBean viewBean; 
   } 
     

   视图范围bean在 @PostConstruct 和请求范围bean的操作方法。您只需要记住，在没有参数的情况下回发到同一视图时， id 可能会丢失。




2. 或者，在bean初始化期间从请求参数映射中手动获取它。

     @ManagedBean 
    @ViewScoped 
   公共类ViewBean {
    
    private Integer id; 
    
    @PostConstruct 
    public void init（）{
    id = Integer.valueOf（FacesContext.getCurrentInstance（）。getExternalContext（）。getRequestParameterMap（）。get（id） ）; 
   } 
   } 
     

   这样初始 id 在整个视图范围内可用。




I need to pass a parameter (POST) to a @managedBean, I used managed properties like this:

@ManagedProperty(value = "#{param.id}")
private int id;

And the scope of the Bean is ViewScope

I end up with this error:

What can I do?

arjan take a look:

My page: Facelet Title

<form method="post" action="faces/index.xhtml">
  <input name="id" value="4" />
  <input type="submit" value="submit" />
</form>

<h:form>
  <h:commandLink value="click" action="index">
    <f:param id="id" name="id" value="20"/>
  </h:commandLink>
</h:form>

解决方案

Two ways:

1. Make the bean request scoped and inject the view scoped one as another @ManagedProperty.

   @ManagedBean
   @RequestScoped
   public class RequestBean {
   
       @ManagedProperty(value="#{param.id}")
       private Integer id;
   
       @ManagedProperty(value="#{viewBean}")
       private ViewBean viewBean;
   }
   

   The view scoped bean is available during @PostConstruct and action methods of request scoped bean. You only need to keep in mind that the id can get lost when you do a postback to the same view without the parameter.

2. Or, grab it manually from the request parameter map during bean's initialization.

   @ManagedBean
   @ViewScoped
   public class ViewBean {
   
       private Integer id;
   
       @PostConstruct
       public void init() {
           id = Integer.valueOf(FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("id"));
       }
   }
   

   This way the initial id is available during the entire view scope.

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