jsp读取request的时候，显示的是内存地址，怎么解决？

public class Department {

    private Integer did;
    private String departmentname;
.......

表单的属性都对应着呢！

<f:form action="save" method="post" modelAttribute="us">

    <f:input path="nama"></f:input>
    <br>
    <f:input path="age"></f:input>
    <br>

    <%
        Map<Integer, String> temp = new HashMap<Integer, String>();
        temp.put(0, "男");
        temp.put(1, "女");
        request.setAttribute("genders", temp);
    %>
    <f:radiobuttons path="gender" items="${genders}"></f:radiobuttons>
    <br>

    <f:select path="department.did" items="${departments}" itemlabel="departmentname" itemValue="did"></f:select>
    <br>
    <input type="submit" value="确定">
</f:form>

然后，给赋值的方法是：

@RequestMapping(value = "/input", method = RequestMethod.GET)
    public String input(Map<String, Object> map) {

        map.put("departments", departmentDao.getDeapartments());
        map.put("us", new User());
        return "input";
    }

departmentDao.getDeapartments()获得的是一个List<User>的集合。

但是，最终显示效果是：

为什么呢？好几次遇到这个问题，在同一条石头绊倒好多次...求帮解决

==================================
给Department加上tostring（）方法后，变成这样

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f标签是啥？spring的form吗
如果是就看这里：
http://docs.spring.io/spring/docs/current/spring-framework-reference/htmlsingle/#view-jsp-formtaglib-selecttag

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要不把departments封装成这个格式？

 List <SelectItem> selectItemList = new ArrayList<SelectItem>();
for（Department item:departments）{
    selectItemList.add(new SelectItem(item.getDid(), item.getDepartmentname()));
}

我也是渣渣，不要见笑