f:convertDateTime support for Java8 LocalDate / LocalDateTime? [duplicate]

Answer 1

Just write your own Converter and extend the javax.faces.convert.DateTimeConverter - that way you can Reuse all the attributes that supports. Also it will take care of Localization too. Unfortunately it's a bit more complicated to write a Converter with Attributes.

Create component
First write your own Converter that extends javax.faces.convert.DateTimeConverter - just let the super-calls do all the work (including locale-stuff) and convert the result from/to LocalDate.

@FacesConverter(value = LocalDateConverter.ID)
public class LocalDateConverter extends DateTimeConverter {
    public static final String ID = "com.example.LocalDateConverter";

    @Override
    public Object getAsObject(FacesContext facesContext, UIComponent uiComponent, String value) {
        Object o = super.getAsObject(facesContext, uiComponent, value);

        if (o == null) {
            return null;
        }

        if (o instanceof Date) {
            Instant instant = Instant.ofEpochMilli(((Date) o).getTime());
            return LocalDateTime.ofInstant(instant, ZoneId.systemDefault()).toLocalDate();
        } else {
            throw new IllegalArgumentException(String.format("value=%s could not be converted to a LocalDate, result super.getAsObject=%s", value, o));
        }
    }

    @Override
    public String getAsString(FacesContext facesContext, UIComponent uiComponent, Object value) {
        if (value == null) {
            return super.getAsString(facesContext, uiComponent,value);
        }

        if (value instanceof LocalDate) {
            LocalDate lDate = (LocalDate) value;
            Instant instant = lDate.atStartOfDay().atZone(ZoneId.systemDefault()).toInstant();
            Date date = Date.from(instant);
            return super.getAsString(facesContext, uiComponent, date);
        } else {
            throw new IllegalArgumentException(String.format("value=%s is not a instanceof LocalDate", value));
        }
    }
}

Then create a file LocalDateConverter-taglib.xml in META-INF:

    http://example.com/LocalDateConverter
    
        convertLocalDate
        
            com.example.LocalDateConverter
        
    

And lastly, register the taglib in web.xml:

    javax.faces.FACELETS_LIBRARIES
    /META-INF/LocalDateConverter-taglib.xml

Usage
To use the new Tag in your JSF-Page add the new Taglib xmlns:ldc="http://example.com/LocalDateConverter" and use the tag: