Java 如何在数据列表中加载数据

我有一个名为ball的数据库，它有和ID以及一个名称

我使用CRUD生成了实体和jsf页面

加入

<h:form>
    <h:dataTable id="btable" value="#{ballController.items}" var="item">
         <h:column>
             <h:outputText value="#{item.id}"/>
         </h:column>
         <h:column>
             <h:outputText value="#{item.bname}"/>
         </h:column>
    </h:dataTable> 
</h:form>

在datatable中生成数据

但是没有方法重新加载数据

我试着创建一个按钮

<h:commandButton action="#{ballCOntroller.getItems}" value="test">
      <f:ajax execute="@form" render="btable" />
</h:commandButton> 

---

以下方法对你有效吗

JSF页面

<h:form>
    <h:dataTable id="btable" value="#{ballController.items}" var="item">
         <h:column>
             <h:outputText value="#{item.id}"/>
         </h:column>
         <h:column>
             <h:outputText value="#{item.bname}"/>
         </h:column>
    </h:dataTable>
    <h:commandButton action="#{ballController.retrieveItems}" value="Reload">
        <f:ajax execute="@form" render="btable" />
    </h:commandButton> 
</h:form>

---

您好，在按下重新加载按钮后，我收到了这个错误

serverError:class java.lang.IndexOutOfBoundsException索引：0，大小：0

button@RowiePo您是否调试过出现此问题的地方：在

getPagination

或

createPageDataModel

函数中？这确实是对问题中所述问题的回答。@LuiggiMendoza我还有一个创建函数，我注意到在我创建一个球并将其插入数据库后，当我按下重新加载函数时，会弹出错误，但是如果我直接到数据库手动删除或添加数据，重新加载函数工作正常。我将更新这个问题，并为您添加创建函数来检查顺便说一句，错误不会显示在我的Glash Fish服务器上，它会像jquery一样弹出alert@RowiePo请仔细检查您的保存功能。我认为上述方法应该适用于数据重新加载。

@ManagedBean(name = "ballController")
@ViewScoped
public class ballController implements Serializable {

    private ball current;
    private DataModel items = null;
    @EJB
    private ballFacade ejbFacade;
    private PaginationHelper pagination;
    private int selectedItemIndex;

    public ballController() {
    }

    public ball getSelected() {
        if (current == null) {
            current = new ball();
            selectedItemIndex = -1;
        }
        return current;
    }

    private ballFacade getFacade() {
        return ejbFacade;
    }

    public PaginationHelper getPagination() {
        if (pagination == null) {
            pagination = new PaginationHelper(10) {
                @Override
                public int getItemsCount() {
                    return getFacade().count();
                }

                @Override
                public DataModel createPageDataModel() {
                    return new ListDataModel(getFacade().findRange(new int[]{getPageFirstItem(), getPageFirstItem() + getPageSize()}));
                }
            };
        }
        return pagination;
    }

    public String prepareList() {
        recreateModel();
        return "List";
    }

    public String prepareView() {
        current = (ball) getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        return "View";
    }

    public String prepareCreate() {
        current = new ball();
        selectedItemIndex = -1;
        return "index";
    }

    public String create() {
        try {

            getFacade().create(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("ballCreated"));
            return prepareCreate();
//            return null;
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }

    public String prepareEdit() {
        current = (ball) getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        return "Edit";
    }

    public String update() {
        try {
            getFacade().edit(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("ballUpdated"));
            return "View";
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }

    public String destroy() {
        current = (ball) getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        performDestroy();
        recreatePagination();
        recreateModel();
        return "List";
    }

    public String destroyAndView() {
        performDestroy();
        recreateModel();
        updateCurrentItem();
        if (selectedItemIndex >= 0) {
            return "View";
        } else {
            // all items were removed - go back to list
            recreateModel();
            return "List";
        }
    }

    private void performDestroy() {
        try {
            getFacade().remove(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("ballDeleted"));
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        }
    }

    private void updateCurrentItem() {
        int count = getFacade().count();
        if (selectedItemIndex >= count) {
            // selected index cannot be bigger than number of items:
            selectedItemIndex = count - 1;
            // go to previous page if last page disappeared:
            if (pagination.getPageFirstItem() >= count) {
                pagination.previousPage();
            }
        }
        if (selectedItemIndex >= 0) {
            current = getFacade().findRange(new int[]{selectedItemIndex, selectedItemIndex + 1}).get(0);
        }
    }

    public DataModel getItems() {
        if (items == null) {
            items = getPagination().createPageDataModel();
        }
        return items;

    }

    private void recreateModel() {
        items = null;
    }

    private void recreatePagination() {
        pagination = null;
    }

    public String next() {
        getPagination().nextPage();
        recreateModel();
        return "List";
    }

    public String previous() {
        getPagination().previousPage();
        recreateModel();
        return "List";
    }

    public SelectItem[] getItemsAvailableSelectMany() {
        return JsfUtil.getSelectItems(ejbFacade.findAll(), false);
    }

    public SelectItem[] getItemsAvailableSelectOne() {
        return JsfUtil.getSelectItems(ejbFacade.findAll(), true);
    }

    @FacesConverter(forClass = ball.class)
    public static class ballControllerConverter implements Converter {

        public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
            if (value == null || value.length() == 0) {
                return null;
            }
            ballController controller = (ballController) facesContext.getApplication().getELResolver().
                    getValue(facesContext.getELContext(), null, "ballController");
            return controller.ejbFacade.find(getKey(value));
        }

        java.lang.Integer getKey(String value) {
            java.lang.Integer key;
            key = Integer.valueOf(value);
            return key;
        }

        String getStringKey(java.lang.Integer value) {
            StringBuffer sb = new StringBuffer();
            sb.append(value);
            return sb.toString();
        }

        public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
            if (object == null) {
                return null;
            }
            if (object instanceof ball) {
                ball o = (ball) object;
                return getStringKey(o.getId());
            } else {
                throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected type: " + ball.class.getName());
            }
        }
    }
}

<h:form>
    <h:dataTable id="btable" value="#{ballController.items}" var="item">
         <h:column>
             <h:outputText value="#{item.id}"/>
         </h:column>
         <h:column>
             <h:outputText value="#{item.bname}"/>
         </h:column>
    </h:dataTable>
    <h:commandButton action="#{ballController.retrieveItems}" value="Reload">
        <f:ajax execute="@form" render="btable" />
    </h:commandButton> 
</h:form>

private DataModel items;
//Getter and Setter Methods

@PostConstruct
public void init() {
    items = getPagination().createPageDataModel();
}

public void retrieveItems() {
    items = getPagination().createPageDataModel();
}