JSF 浮点转换
我在此处的项目中使用 JSF 1.2 和 IceFaces 1.8。
我有一个页面基本上是一大堆浮点数字段的大编辑网格。这是通过页面上的 inputText 字段指向具有原始 float 类型的值对象来实现的。
现在，由于新要求看到某些字段可为空，我想更改值对象使用Float对象而不是基本类型。我认为我不需要对页面做任何事情来适应这一点。
但是，当我进行更改时，出现以下错误：
/pages/page.xhtml @79,14 value="#{row.targetValue}": java.lang.IllegalArgumentException: 参数类型不匹配
并且
/pages/page.xhtml @79,14 value="#{row.targetValue}": java.lang.IllegalArgumentException: java.lang.ClassCastException@1449aa1
页面如下所示：
<ice:inputText value="#{row.targetValue}" size="4">
<f:convertNumber pattern="###.#" />
</ice:inputText>
我也尝试添加
我确信我可能错过了一些非常简单的东西，但我已经盯着这个有一段时间了，没有立即明显的答案！
I'm using JSF 1.2 with IceFaces 1.8 in a project here.
I have a page which is basically a big edit grid for a whole bunch of floating-point number fields. This is implemented with inputText fields on the page pointing at a value object with primitive float types
Now, as a new requirement sees some of the fields be nullable, I wanted to change the value object to use Float objects rather than primitive types. I didn't think I'd need to do anything to the page to accomodate this.
However, when I make the change I get the following error:
/pages/page.xhtml @79,14 value="#{row.targetValue}": java.lang.IllegalArgumentException: argument type mismatch
And
/pages/page.xhtml @79,14 value="#{row.targetValue}": java.lang.IllegalArgumentException: java.lang.ClassCastException@1449aa1
The page looks like this:
<ice:inputText value="#{row.targetValue}" size="4">
<f:convertNumber pattern="###.#" />
</ice:inputText>
I've also tried adding in <f:convert convertId="javax.faces.Float" /> in there as well but that doesn't seem to work either! Neither does changing the value object types to Double.
I'm sure I'm probably missing something really simple but I've been staring at this for a while now and no answers are immediately obvious!
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经过一番调查（参见此处，此处以及此处）
似乎有三种解决方案：
不幸的是，由于其他原因，#1 不适合我，而且我现在不想编写自己的转换器。但是，如果我更改代码以删除 ConvertNumber，一切似乎都可以正常工作。 （我还将值对象类型更新为 Double，这是我查看的链接之一中建议的）。
这可以防止出现异常，而且看起来 JSF 仍在做我希望它做的事情。只是令人烦恼的是，您似乎无法在同一实例中指定
convertNumber和转换类型。After some investigation (see e.g. here, here and here) that
<f:convertNumber>is the problem. It seems that the number it converts to is dependent on the input you give it - it could be an integer or a floating point number. In other words, it doesn't look at the target type - it just generates an instance of java.lang.Number. Which is hardly ideal, although I can't determine whether this is because somewhere I'm using an old version of JSF or EL or something like that.There seem to be three solutions:
java.lang.Numberas your value object type;<f:convertNumber>.Unfortunately #1 isn't an option for me for other reasons, and I don't want to write my own converter at the moment. However if I change the code to remove the convertNumber, everything seems to work OK. (I've also updated the value object type to
Doublewhich was suggested in one of the links I looked at).That prevents the exceptions, and it looks like JSF is still doing what I want it to do. Just annoying that it seems you can't specify
convertNumberand the convert type in the same instance.