问题
When I set required="true" in a <h:inputText>, it still allows blank spaces. I have been trying to modify the jsf-api.jar but I could not understand how to generate new a JAR, so I tried to modify the isEmpty() method from UIInput class and compile it, open the jsf-api.jar and replace it with the new one, but it did not work.
What I need is to do trim() when the user writes in a <h:inputText> to do not allow blank spaces. How can I achieve this?
If you want to download the jsf-api.jar resource, you can do it, just read how to at: http://javaserverfaces.java.net/checkout.html.
回答1:
That's normal and natural behaviour and not JSF specific. A blank space may be perfectly valid input. The required="true" only kicks in on empty inputs, not in filled inputs. In JSF you can however just create a Converter for String class to automatically trim the whitespace.
@FacesConverter(forClass=String.class)
public class StringTrimmer implements Converter {
@Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
return value != null ? value.trim() : null;
}
@Override
public String getAsString(FacesContext context, UIComponent component, Object value) {
return (String) value;
}
}
Put this class somewhere in your project. It'll be registered automatically thanks to @FacesConverter and invoked automatically for every String entry thanks to forClass=String.class.
No need to hack the JSF API/impl. This makes no sense.
回答2:
If you want to turn off the behavior that BalusC notes as one of the answers as standard JSF behavior, you can modify the web.xml and include the following.
<context-param>
<param-name>javax.faces.INTERPRET_EMPTY_STRING_SUBMITTED_VALUES_AS_NULL</param-name>
<param-value>true</param-value>
<context-param>
This will trigger the JSF framework to consider the values null which may be preferable, or an alternative to the answer from BalusC.
来源：https://stackoverflow.com/questions/8326398/why-does-hinputtext-required-true-allow-blank-spaces