@Override
    protected void encodeMarkup(FacesContext context, DatePicker component, String value) throws IOException {
        ResponseWriter writer = context.getResponseWriter();
        String clientId = component.getClientId(context);
        String styleClass = component.getStyleClass();
        styleClass = (styleClass == null) ? UICalendar.CONTAINER_CLASS : UICalendar.CONTAINER_CLASS + " " + styleClass;
        styleClass = DatePicker.CONTAINER_EXTENSION_CLASS + " " + styleClass;
        String inputId = clientId + "_input";
        boolean inline = component.isInline();

        writer.startElement("span", component);
        writer.writeAttribute("id", clientId, null);
        writer.writeAttribute("class", styleClass, null);

        if (component.getStyle() != null) {
            writer.writeAttribute("style", component.getStyle(), null);
        }

        //input
        encodeInput(context, component, inputId, value, !inline);

        writer.endElement("span");

    }
Initializes the default settings for the DatePicker component based on its pattern and value type.

@param context the FacesContext instance
@param datePicker the DatePicker component to initialize
primefaces/src/main/java/org/primefaces/component/datepicker/DatePickerRenderer.java