java - 从 Spring 表单复选框元素接收 EnumSet？

Question

我看到了一些与此主题相关的问题，但似乎没有一个与我所追求的完全匹配。

我有一个表单，我希望用户能够从复选框列表中选择多个项目(由枚举支持)，并将其作为集合接收。我有以下内容(以天为例)

我的枚举:

public enum Day {
MONDAY,
TUESDAY,
WEDNESDAY,
THURSDAY,
FRIDAY,
SATURDAY,
SUNDAY
}

将枚举值发送到 Controller 中的页面以显示为选项:

model.addAttribute("allDays", Day.values());

将选项写入复选框并映射到正确的表单字段:

<form:form method="get" modelAttribute="filterForm" commandName="filterForm">
    <c:forEach items="${allDays}" var="item">
        <form:checkbox path="days" value="${item.name()}" label="${item.name()}"/>
    </c:forEach>
</form:form>

支持表单的表单对象:

public class FilterForm {

    private EnumSet<Day> days;

    public EnumSet<Day> getDays() {
        return days;
    }

    public void setDays(EnumSet<Day> days) {
        this.days = days;
    }
}

这可以正确显示选项，但是当我尝试提交时，出现错误:

org.springframework.validation.BindException: org.springframework.validation.BeanPropertyBindingResult: 1 errors Field error in object 'filterForm' on field 'days': rejected value [0,1]; codes [typeMismatch.filterForm.days,typeMismatch.days,typeMismatch.java.util.EnumSet,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [filterForm.days,days]; arguments []; default message [days]]; default message [Failed to convert property value of type 'java.lang.String[]' to required type 'java.util.EnumSet' for property 'days'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type java.lang.String[] to type java.util.EnumSet for value '{0, 1}'; nested exception is java.lang.IllegalArgumentException: Could not instantiate Collection type: java.util.EnumSet] org.springframework.web.method.annotation.ModelAttributeMethodProcessor.resolveArgument(ModelAttributeMethodProcessor.java:111) org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:75) org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:156) org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:117) org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96) org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617) org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578) org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923) org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852) org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778) javax.servlet.http.HttpServlet.service(HttpServlet.java:621) javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

知道问题是什么或者是否有更好的方法来实现这一目标？ 谢谢

Answer 1

我设法通过将表单更改为使用 Set 而不是 EnumSet 来解决此问题，并且我还修改了标记，以便提交的值保持选中状态:

<form:form method="get" modelAttribute="filterForm" commandName="filterForm">
    <form:checkboxes items="${allDays}" path="days" />
</form:form>

和表格:

public class FilterForm {

    private Set<Day> days;

    public Set<Day> getDays() {
        return days;
    }

    public void setDays(Set<Day> days) {
        this.days = days;
    }
}