从JSF传递枚举值作为参数（重新访问）

问题描述

限时删除！！

这个问题已经解决了这个问题，但是提出的解决方案对我来说没有效果。我在支持bean中定义了以下枚举：

  public enum QueryScope {
 SUBMITTED（由我提交） ，ASSIGNED（分配给我），ALL（所有项目）; 
 
 private final String description; 
 
 public String getDescription（）{
 return description; 
} 
 
 QueryScope（String description）{
 this.description = description; 
} 
} 
  

然后我将其用作方法参数

  public void test（QueryScope scope）{
 // do something 
} 
  

通过EL在我的JSF页面中使用它

 < h：commandButton 
 id =commandButton_test
 value =测试枚举
 action =＃{backingBean.test（'SUBMITTED'）}/> 
  

迄今为止，与原始问题提出的问题相同。但是我必须处理一个 javax.servlet.ServletException：找不到方法：％fully_qualified_pa​​ckage_name％.BackingBean.test（java.lang.String）。

所以似乎JSF正在解释方法调用，就像我想调用一个String作为参数类型（当然不存在）的方法 - 因此不会发生隐式转换。

在这个例子中，与上述相关的行为有什么不同的因素？

解决方案您可以在 backingBean 中编写一个方法，其中包含枚举参数：

 <！ - 这不行，EL不支持枚举： - > 
< h：commandButton ... action =＃{backingBean.test（QueryScope.SUBMITTED）}/> 
 
 // backingBean：
 public void test（QueryScope queryScope）{
 // your impl 
} 
  

但是，提出的解决方案不使用枚举，它使用 String 。这是因为EL根本不支持枚举：

 <！ - 这将工作，EL支持String： - > 
< h：commandButton ... action =＃{backingBean.test（'SUBMITTED'）}/> 
 
 // backingBean：
 public void test（String queryScopeString）{
 QueryScope queryScope = QueryScope.valueOf（queryScopeString）; 
 // your impl 
} 
  




Passing a Enum value as a parameter from JSF

This question already deals with this issue, however the proposed solution has not worked for me. I define the following enumeration in my backing bean:

public enum QueryScope {
  SUBMITTED("Submitted by me"), ASSIGNED("Assigned to me"), ALL("All items");

  private final String description;

  public String getDescription() {
    return description;
  }

  QueryScope(String description) {
    this.description = description;
  }
}

Then I use it as a method parameter

public void test(QueryScope scope) {
  // do something
}

And use it via EL in my JSF page

<h:commandButton
      id        = "commandButton_test"
      value     = "Testing enumerations"
      action    = "#{backingBean.test('SUBMITTED')}" />

So far so good - identical to the problem posed in the original question. However I have to deal with a javax.servlet.ServletException: Method not found: %fully_qualified_package_name%.BackingBean.test(java.lang.String).

So it seems that JSF is interpreting the method call as if I would like to call a method with String as parameter type (which of course does not exist) - therefore no implicit conversion takes place.

What could be the factor that makes the behavior differ in this example from the aforelinked?

解决方案

In your backingBean, you may have written a method with the enum parameter:

<!-- This won't work, EL doesn't support Enum: -->
<h:commandButton ... action="#{backingBean.test(QueryScope.SUBMITTED)}" />

// backingBean:
public void test(QueryScope queryScope) {
    // your impl
}

But, the proposed solution does not use enum, it uses String. That's because EL doesn't support enum at all:

<!-- This will work, EL does support String: -->
<h:commandButton ... action="#{backingBean.test('SUBMITTED')}" />

// backingBean:
public void test(String queryScopeString) {
    QueryScope queryScope = QueryScope.valueOf(queryScopeString);
    // your impl
}

这篇关于从JSF传递枚举值作为参数（重新访问）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！

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