java - 执行 struts 2 操作类时给出空 json 结果

Question

我尝试使用 hibernate ORM 从数据库检索数据，并使用 Struts2 将输出作为 json 结果。 一切正常，从数据库检索数据， 但对于 json 结果，我只得到 {}。

我认为我的编码出了问题。但需要一些帮助才能弄清楚。

Here is my Action class :

@ParentPackage("json-default")
public class SocialIconsAction extends ActionSupport {

    private List<TiendayaCurrencies> _currency;

    public List<TiendayaCurrencies> getCurrency() {
        return _currency;
    }

    public void setCurrency(List<TiendayaCurrencies> _currency) {
        this._currency = _currency;
    }

    @Action(value = "currencies", results = {
        @Result(name = "success", type = "json", params = {"includeProperties",
            "_currency\\[\\d+\\]\\..*"})})
    @Override
    public String execute() {
        _currency = loadCurrencies();

        /*Nothing wrong with the DB results.Just to  test everything works fine.*/
        //for (TiendayaCurrencies _currency1 : _currency) {
           // System.out.println("Title - "+_currency1.getTitle());
       // }


        return SUCCESS;
    }

    private List<TiendayaCurrencies> loadCurrencies() {
        Session session = com.tiendaya.connection.HibernateUtil.
                getSessionFactory().openSession();
        List<TiendayaCurrencies> cList = session.
                createCriteria(TiendayaCurrencies.class).list();

        return cList;
    }
}

Pojo class :

public class TiendayaCurrencies{


     private Integer id;
     private String title;
     private String code;
     private String symbolLeft;
     private String symbolRight;
     private char decimalPlace;
     ...

includeProperties 有什么问题吗？(我能想到的唯一地方..)任何人都可以建议一种方法..我已经尝试了一切...

Edit :

public class SocialIconsAction extends ActionSupport {

    private List<TiendayaCurrencies> _currency=new ArrayList<>();
    private String sample="working";

    public String getSample() {
        return sample;
    }

    public void setSample(String sample) {
        this.sample = sample;
    }
    ...


@Action(value = "currencies", results = {
@Result(name = "success", type = "json", params = {"includeProperties", "sample"})})

...

作为 json 输出，它给了我: {"sample":"working"} 这意味着它工作正常。那么为什么它不能与ArrayList一起使用？？

Answer 1

Struts2 JSON 插件将序列化您的整个操作，包括带有 getter 的所有(非 transient )属性。

由于您隐藏了变量(绝对不是最佳实践，特别是因为它迫使您手动编写每个 getter 和 setter...brr)，并且变量和 getter 有不同的名称，因此您指向变量，但您应该指向 getter(然后是 currency 而不是 _currency):

@Action(value = "currencies", results = {
    @Result(name = "success", 
            type = "json", 
          params = {"includeProperties","currency\\[\\d+\\]\\..*"})
})

另请注意，您可以指定根对象，这通常优于 includeProperties 技术，如 described here :

@Action(value = "currencies", results = {
    @Result(name = "success", 
            type = "json", 
          params = {"root","currency"})
})