非请求范围Bean中的@ManagedProperty（value ="＃{param.id}"） [英] @ManagedProperty(value = "#{param.id}") in a non-request Scope Bean

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

<我最终得到了这个错误：

无法创建托管bean收据。发现了以下问题： - 表达式＃{param.id}，request引用的对象的范围比引用的托管bean视图范围短

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 <期间可用/ code>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:

Unable to create managed bean receipt. The following problems were found: - The scope of the object referenced by expression #{param.id}, request, is shorter than the referring managed beans scope of view

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.

这篇关于非请求范围Bean中的@ManagedProperty（value =&quot;＃{param.id}&quot;）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！