我有一个带有支撑对象的弹簧形式。形式是这样的-

<sf:form cssClass="form-horizontal" commandName="campaignModel" method="post">
<sf:input path="campaign.name" class="form-control" /> 
<sf:input path="landingPageModels.landingPage.url" class="form-control" />
</sf:form>

模型类（表单支持对象）-

CampaignModel.java

public class CampaignModel { 
private Campaign campaign = new CampaignImpl();
private List<LandingPageModel> landingPageModels = new Arraylist<LandingPageModel>;
public Campaign getCampaign() {
    return campaign;
}
public void setCampaign(Campaign campaign) {
    this.campaign = campaign;
}
public List<LandingPageModel> getLandingPageModels() {
    return landingPageModels;
}
public void setLandingPageModels(List<LandingPageModel> landingPageModels) {
    this.landingPageModels = landingPageModels;
}

LandingPageModel.java 是-

public class LandingPageModel {
private LandingPage landingPage = new LandingPageImpl();
private List<LandingPageParameterImpl> landingPageParameters = new ArrayList<LandingPageParameterImpl>();

public LandingPage getLandingPage() {
    return landingPage;
}
public void setLandingPage(LandingPage landingPage) {
    this.landingPage = landingPage;
}
public List<LandingPageParameterImpl> getLandingPageParameters() {
    return landingPageParameters;
}
public void setLandingPageParameters(List<LandingPageParameterImpl> landingPageParameters) {
    this.landingPageParameters = landingPageParameters;
} 
}

LandingPage.java 是-

public class LandingPageImpl extends EntityImpl implements LandingPage {

private String url;

public String getUrl() {
    return url;
}

public void setUrl(String url) {
    this.url = url;
} }

所以我希望我可以在着陆页模型列表中插入许多着陆页对象（具有自己的url属性）。这意味着我可以拥有多个具有url属性的输入标签，例如：

<sf:input path="landingPageModels.landingPage.url" class="form-control" />
<sf:input path="landingPageModels.landingPage.url" class="form-control" />
<sf:input path="landingPageModels.landingPage.url" class="form-control" />

但是在执行此代码时，spring给我一个错误，即LandingPageModels的LandingPage属性没有getter
setter方法。如何解决这个问题以及如何采取这样的多重价值？