struts2迭代器中填充的列表值列表

Question

就我而言，这有点棘手。我只是在个人对象中有另一个列表，它被称为状态。如下：

public class People {
    private int id;
    private String name;
    private List<State> states;
    // Plus setters/getters
}

public class State {
    private int id;
private String stateAbbr;
private String stateName;
public State (String stateAbbr, String stateName) {
this.stateAbbr = stateAbbr;
this.stateName = stateName;
}
   // Plus setters/getters
}

动作类：

public class PersonAction extends ActionSupport {
private List<People> peopleList;

public List<People> getPeopleList() {
    return peopleList;
}

public void setPeopleList(List<People> peopleList) {
    this.peopleList = peopleList;
}

//Initial Load method
@Override
public String execute() {
    peopleList = new ArrayList<People>();

    int alpha = 65;
    for(int i = 0; i < 3 ; i++) {
        People people = new People();
        people.setId(i);
        people.setName(String.valueOf((char)alpha++));
        peopleList.add(people);
    }

    for (People people : peopleList){
        State state = new State("BC", "BritishColumbia");
        List<State> states = new ArrayList<State>();
        states.add(state);
        state = new State("AC", "AppleColumbia");
        states.add(state);
        people.setStates(states);
    }
    return SUCCESS;
}

//Function that handles the form submit
public String updatePerson() {
    for(People people : peopleList) {
        System.out.println(people.getId() + ":" + people.getName());
    }

    return SUCCESS;
}

}

JSP 页面

<s:form action="doUpdate">
    <s:iterator value="peopleList" status="stat" var="people">
        <s:textfield value="%{#people.name}"
            name="peopleList[%{#stat.index}].name" />
        <s:iterator value="states" status="stateStatus" var="personState">
            <s:textfield value="%{#personState.stateAbbr}"
                name="peopleList[%{#stat.index}].states[%{#stateStatus.index}].stateAbbr" label="Abbr State" />
            <br />
        </s:iterator>
    </s:iterator>
    <s:submit value="Submit" />
</s:form>

当我提交此页面时，我本人收到 states is [null]，为什么？

Answer 1

新问题的答案：

如果您的 State 类没有默认构造函数，S2/OGNL 将无法实例化该类的空版本。

提供一个默认（无参数）构造函数，将填充此人的状态列表。

（太糟糕了，两个答案都不能被接受；）

Answer 2

state 属性是特定人员的属性。在这种情况下，您需要将状态“连接”到persons[%{#stat.index}]，所以：

<s:textfield ... 
    name="persons[%{#stat.index}].states[%{#stateStatus.index}]" .../>

迭代器状态变量有一个 index 属性，可以避免您在 IteratorStatus (docs) 实例上进行的数学运算：

<s:textfield ... name="persons[%{#stat.index}].name" />

另外，根据您使用的 S2 版本，您可能不需要# 字符。