jsf - @FacesConverter forClass-Attribute 不起作用

Question

我只想测试 @FacesConverter 功能并卡在 forClass-atrribute 上 - 它不起作用 - 这是我的示例:

转换器类:

@FacesConverter(forClass = Double.class)
public class TextToDoubleConverter implements Converter {

    @Override
    public Double getAsObject(FacesContext context, UIComponent component, String value) throws ConverterException {
        Double doubledValue = null;
        try {
            doubledValue = new Double(value);
        } catch (NumberFormatException e) {
            FacesMessage facesMessage = new FacesMessage("Fehler: ...");
            facesMessage.setSeverity(FacesMessage.SEVERITY_ERROR);
            throw new ConverterException(facesMessage);
        }

        return doubledValue;
    }

    @Override
    public String getAsString(FacesContext context, UIComponent component, Object value) {
        return value.toString();
    }

}

托管Bean:

@Model
public class SomeBean {


    private Double someCommvertDouble;


    public Double getSomeCommvertDouble() {
        return someCommvertDouble;
    }

    public void setSomeCommvertDouble(Double someCommvertDouble) {
        this.someCommvertDouble = someCommvertDouble;
    }
}

index.xhtml:

    <h:form>
    <h:inputText value="#{someBean.someCommvertDouble}">
<!--        <f:converter converterId="com.java.ee.jsf.TextToIntConverter"/>  -->    
 </h:inputText>

    </h:form>

这里出了什么问题？

Answer 1

@FacesConverter(forClass) 仅适用于还没有 built-in converter 的自定义类型。存在。 Double 类型已经有一个内置转换器， DoubleConverter 。 faces-config.xml 中已定义的任何转换器(例如内置转换器)始终比使用 @FacesConverter 注释的转换器具有更高的优先级。

只有在 web 应用的 faces-config.xml 中显式注册转换器(而不是进行注释)时，转换器才会工作。

<converter>
    <converter-for-class>java.lang.Double</converter-for-class>
    <converter-class>com.example.YourDoubleConverter</converter-class>
</converter>

顺便说一句，请考虑从 DoubleConverter 或 NumberConverter 扩展并委托(delegate)给它。您可以在下面的链接中找到一些与密切相关的问题的具体示例。

另请参阅:

• validating decimals inputs in JSF
• Need <f:convertNumber> to throw error when fractions or separator characters are used
• convertNumber shows 0,00 as a negative value
• How to standardize convertnumber usage in JSF for various components?