Struts2下拉列表示例问题

我正在尝试使用struts2标签处理下拉列表。但到目前为止我还没有成功：下面是.jsp页面、action类、struts.xml文件和所有相关代码。任何帮助都将不胜感激。多谢各位

注意：我收到此错误：->标记“选择”，字段“列表”：请求的列表键“国家/地区”无法解析为集合/数组/映射/枚举/迭代器类型。示例：人或人。{name}-[未知位置]

。。。。。。。。。。。 Index.jsp：

---

}

在本例中，您将使用Country类作为地图。最简单的解决方案是使用适当的getter/setter创建一个名为country的Hashmap属性，并用您需要的内容填充它

然后在JSP中，您可以说：

<s:select label="Country" list="country.keys">

或者你更愿意

<s:select label="Country" list="country.values">

---

工作流程应与上述相反。应该是

action that fills select tag(calls getcountry) -> page with form -> action(to which form will be submitted)

但在我们之上

 page with form -> submitted to action that fills the select, but form has already been displayed.

private String countryAbbr;
private String countryName;

public Country() {
}

public Country(String countryAbbr, String countryName) {
    this.countryAbbr = countryAbbr;
    this.countryName = countryName;
}

public String getCountryName() {
    return countryName;
}

public void setCountryName(String countryName) {
    this.countryName = countryName;
}

public String getCountryAbbr() {
    return countryAbbr;
}

public void setCountryAbbr(String countryAbbr) {
    this.countryAbbr = countryAbbr;
}

<s:select label="Country" list="country.keys">

<s:select label="Country" list="country.values">

action that fills select tag(calls getcountry) -> page with form -> action(to which form will be submitted)

 page with form -> submitted to action that fills the select, but form has already been displayed.