SpringMVC 3 转换返回 String[] 到实体对象

Question

我有一个与 CampaignCities 城市具有一对一关系的实体营销活动。 反过来，CampaignCities 包含一组城市；

营销活动实体

    @Entity 
    @javax.persistence.Table(uniqueConstraints={@UniqueConstraint(columnNames={"name","company_id"}), @UniqueConstraint(columnNames={"id"})})
    public class Campaign implements Serializable {
        /**
         * 
         */
        private static final long serialVersionUID = 1L;

        private Long id;

        @NotEmpty
        @Size(min=1, max=100)
        private String name;

        private Date startDate;

        private Date endDate;

        @Valid
        private Deal deal;

        @Valid
        private Company company;

        @OneToOne
        private CampaignCities cities = new CampaignCities();

营销活动城市实体

@Entity
public class CampaignCities {
    private long id;
    private Set<City> cities = new HashSet<City>();

    @Id
    @javax.persistence.GeneratedValue(strategy=GenerationType.AUTO)
    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    @OneToMany
    public Set<City> getCities() {
        return cities;
    }

    public void setCities(Set<City> cities) {
        this.cities = cities;
    }
}

城市实体：

@Entity
public class City implements Serializable {
    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    private String name;
    private Long id;

    @javax.persistence.Id
    @javax.persistence.GeneratedValue(strategy=GenerationType.AUTO)
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

}

我的 NewCampaignController

@SessionAttributes(value={"campaign", "campaignCities"})
@Controller
public class NewCampaignController {
    //private static final Logger logger = LoggerFactory.getLogger(NewDealController.class);

    @Autowired
    private CampaignManager campaignManager;
    @Autowired
    private CityManager cityManager;
    @Autowired
    SimpleDateFormat dateFormat;
    @Autowired
    CustomDateEditor dateEditor;

    @RequestMapping(value = "campaign/new", method = RequestMethod.GET)
    public String showForm(Map<String, Object> model) {
        //List<Campaign> campaigns = campaignManager.getCampaigns();
        Campaign campaignForm = new Campaign();
        CampaignCities cities = new CampaignCities();
        cities.setCities(new HashSet<City>(cityManager.getCity()));
        //campaignForm.setCities(cities);
        model.put("campaignCities", cities);
        model.put("campaign", campaignForm);
        return "campaign/new";
    }

    @RequestMapping(value = "campaign/new", method = RequestMethod.POST)
    public String processForm(@Valid Campaign campaignForm, BindingResult result, Map<String,Object> model) {
        new CampaignValidator().validate(campaignForm, result);
        if (result.hasErrors()) {
            return "campaign/new";
        }
        this.campaignManager.saveCampaign(campaignForm);
        model.put("campaign", campaignForm);
        model.put("campaigns", this.campaignManager.getCampaigns());
        return "campaign/added";
    }

我已经能够在其中呈现营销活动一个表单，我已经使用以下方法成功呈现了城市列表：

<form:checkboxes items="${campaignCities.cities}" path="cities" itemLabel="name" itemValue="id" delimiter="<br/>" />

但是，当我提交表单时，我收到以下验证错误。

字段“城市”上的对象“营销活动”中出现字段错误：值被拒绝 [2,1]；代码 [typeMismatch.campaign.cities,typeMismatch.cities,typeMismatch.com.groupdealclone.app.domain.CampaignCities,typeMismatch]; 论点 [org.springframework.context.support.DefaultMessageSourceResolvable： 代码 [campaign.cities,cities]；参数[]；默认消息 [城市]]；默认消息[无法转换类型的属性值 'java.lang.String[]' 为所需类型 属性“城市”的“com.groupdealclone.app.domain.CampaignCities”； 嵌套异常是 java.lang.IllegalStateException：无法转换 将类型 [java.lang.String[]] 的值设置为所需类型 [com.groupdealclone.app.domain.CampaignCities] 属性“城市”： 未找到匹配的编辑器或转换策略]

我试图找出一种在 SpringMVC 3 中处理这个问题的方法，但我已经被困了一天多，但没有成功。我只是想要一个在表单上检查的列表或集合或城市，将其提交到控制器并添加到营销活动中。如何解决转换问题，将返回的 String[] 转换为城市列表或城市集。

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Answer 1

差不多两天后，答案比我想象的要简单。感谢此线程我被引导找到了答案。

在我的 NewCampaignController 中我做了：

@InitBinder
public void initBinder(WebDataBinder binder) {
    dateFormat.setLenient(false);
    binder.registerCustomEditor(Date.class, dateEditor);

    binder.registerCustomEditor(CampaignCities.class, "cities", new PropertyEditorSupport() {
        @Override
        public void setAsText(String text) {
            String [] ids = text.split(",");
            CampaignCities cities = null;
            for(String id:ids){
                if(cities == null)
                    cities = new CampaignCities();
                City city = cityManager.getCity(new Long(id));
                if(city != null)
                    cities.getCities().add(city);

            }
            if(cities != null){
                cities.setId(null);
                setValue(cities);
            }
        }
    });