java - 通过使用Java Server Faces将多个输入字段绑定(bind)到支持bean属性？

假设我有一个月，日和年选择。每个选择一个。现在，我需要将它们绑定到单个后备bean属性-java.util.Date。我如何实现目标？

最佳答案

三种方式：


通过java.util.Calendar使用三个getter和三个setter返回或中转它。
利用Converter，但是这会有点麻烦。
利用诸如rich:calendar之类的第三方组件。


编辑：根据评论，这是选项2的样子。

page.jsp：

<h:form>
    <h:selectOneMenu value="#{myBean.date}">
        <f:converter converterId="datePartConverter" />
        <f:attribute name="part" value="day" />
        <f:selectItems value="#{myBean.days}" />
    </h:selectOneMenu>
    <h:selectOneMenu value="#{myBean.date}">
        <f:converter converterId="datePartConverter" />
        <f:attribute name="part" value="month" />
        <f:selectItems value="#{myBean.months}" />
    </h:selectOneMenu>
    <h:selectOneMenu value="#{myBean.date}">
        <f:converter converterId="datePartConverter" />
        <f:attribute name="part" value="year" />
        <f:selectItems value="#{myBean.years}" />
    </h:selectOneMenu>

    <h:commandButton value="submit" action="#{myBean.submit}"/>
    <h:messages />
</h:form>

mypackage.MyBean：

package mypackage;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import javax.faces.model.SelectItem;

public class MyBean {

    private static List<SelectItem> days = new ArrayList<SelectItem>();
    private static List<SelectItem> months = new ArrayList<SelectItem>();
    private static List<SelectItem> years = new ArrayList<SelectItem>();

    static {
        // Just do your thing to fill them. Only ensure that those are Strings,
        // else you'll need to change the type in Converter accordingly.
        for (int i = 1; i <= 31; i++) days.add(new SelectItem(String.valueOf(i)));
        for (int i = 1; i <= 12; i++) months.add(new SelectItem(String.valueOf(i)));
        for (int i = 2000; i <= 2020; i++) years.add(new SelectItem(String.valueOf(i)));
    }

    private Date date;

    public void submit() {
        // Print submitted date to stdout.
        System.out.println("Submitted date: " + date);
    }

    public List<SelectItem> getDays() {
        return days;
    }

    public List<SelectItem> getMonths() {
        return months;
    }

    public List<SelectItem> getYears() {
        return years;
    }

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

}

mypackage.DatePartConverter：

package mypackage;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Map;

import javax.faces.application.FacesMessage;
import javax.faces.component.UIComponent;
import javax.faces.component.UIInput;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.ConverterException;

public class DatePartConverter implements Converter {

    public Object getAsObject(FacesContext context, UIComponent component, String value) {
        String part = (String) component.getAttributes().get("part");
        Date date = null;

        if (context.getRenderResponse()) {
            // Convert any default/selected date for display.
            Date selectedDate = (Date) ((UIInput) component).getValue();
            if (selectedDate != null) {
                if (("day".equals(part) && new SimpleDateFormat("d").format(selectedDate).equals(value))
                    || ("month".equals(part) && new SimpleDateFormat("M").format(selectedDate).equals(value))
                    || ("year".equals(part) && new SimpleDateFormat("yyyy").format(selectedDate).equals(value)))
                {
                    date = selectedDate;
                }
            }
        } else {
            // Convert submitted date after submit.
            Map<String, Object> map = context.getExternalContext().getRequestMap();
            if ("day".equals(part)) {
                map.put("DatePartConverter.day", value); // Save until we have all parts.
            } else if ("month".equals(part)) {
                map.put("DatePartConverter.month", value); // Save until we have all parts.
            } else if ("year".equals(part)) {
                String day = (String) map.get("DatePartConverter.day");
                String month = (String) map.get("DatePartConverter.month");
                String dateString = String.format("%s-%s-%s", day, month, value);

                try {
                    date = new SimpleDateFormat("d-M-yyyy").parse(dateString);
                } catch (ParseException e) {
                    throw new ConverterException(new FacesMessage(e.getMessage()), e);
                }
            }
        }

        return date;
    }

}

    public String getAsString(FacesContext context, UIComponent component, Object value) {
        // Not relevant here. Just return SelectItem's value.
        return (String) value;
    }

faces-config.xml

<converter>
    <converter-id>datePartConverter</converter-id>
    <converter-class>mypackage.DatePartConverter</converter-class>
</converter>

<managed-bean>
    <managed-bean-name>myBean</managed-bean-name>
    <managed-bean-class>mypackage.MyBean</managed-bean-class>
    <managed-bean-scope>request</managed-bean-scope>
</managed-bean>

请注意，没有Validator，并且SimpleDateFormat默认为lenient。因此，例如选择11月31日将产生12月1日。如果要对此发出警告，则可能需要自己实施DatePartValidator。