Tidak ada serializer yang ditemukan untuk kelas (untuk menghindari pengecualian, nonaktifkan SerializationFeature.FAIL_ON_EMPTY_BEANS)

Tujuan: Membuat API yang memungkinkan saya mencari data di jurnal artikel, mengambil datanya di kelas Item, menampilkannya dalam format Json. Jalur: Saya membuat proyek di Liferay 6.1 menggunakan plugin Service Builder Portlet. Di file service.xml saya, saya membuat entitas Item. Bidang di entitas ini diperbarui dengan data log artikel yang dipulihkan. Data ini kemudian ditampilkan di JSON.

Masalah yang dihadapi: Saya dapat menampilkan data dalam JSON di konsol Eclipse dengan _log.info (Item). Jadi saya mendapatkannya kembali, tapi saya tidak bisa mengirimkannya melalui Tukang Pos.

Dia menunjukkan kesalahan ini kepada saya: No serializer found for class java.util.Collections$3 and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: com.beorn.tm.synchro.model.impl.ItemImpl["expandoBridge"]->$Proxy760["attributeNames"])

Kelas saya yang berbeda:

public class SynchroApplication extends ResourceConfig {

    public SynchroApplication() {
        //packages("com.beorn.tm.api");
        register(BanqueRestService.class);
        register(HelloWS.class);
        register(JournalArticleRestService.class);

        register(JacksonFeature.class);

        //Register Auth filter 
        register(AuthenticationFilter.class);
    }

       public static ObjectMapper getObjectMapper() {

           ObjectMapper mapper = new ObjectMapper();

           mapper.configure(com.fasterxml.jackson.databind.SerializationFeature.
                    WRITE_DATES_AS_TIMESTAMPS, true);

            mapper.setVisibility(mapper.getSerializationConfig().getDefaultVisibilityChecker()
                    .withFieldVisibility(JsonAutoDetect.Visibility.NONE)
                    .withGetterVisibility(JsonAutoDetect.Visibility.ANY)
                    .withSetterVisibility(JsonAutoDetect.Visibility.ANY)
                    .withCreatorVisibility(JsonAutoDetect.Visibility.NONE));

            mapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY);

            mapper.enable(SerializationFeature.INDENT_OUTPUT);

            mapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);

            return mapper;
        }

        public static String toJson(Object c) throws JsonProcessingException {
            ObjectMapper mapper = getObjectMapper();
            return mapper.writeValueAsString(c);
        }

        public static JsonNode fromJson(String input) throws Exception {
            ObjectMapper mapper = getObjectMapper();
            return mapper.readTree(input);
        }
}

@Path("synchro")
public class JournalArticleRestService {

    private static final Log _log = LogFactoryUtil.getLog(JournalArticleRestService.class);

    @GET
    @Path("/date")
    @Produces(MediaType.APPLICATION_JSON)
    public Item getJournalArticleAfter01012019() {

        SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
        Locale locale = Locale.FRANCE;

        ItemImpl item = new ItemImpl();


        try {
            Date date01012019 = sdf.parse("01/01/2019");
            //Companies
            List<Company> companies = CompanyLocalServiceUtil.getCompanies();
            for(Company company : companies) {
                long companyId = company.getCompanyId();
                //Groups
                List<Group> groups = GroupLocalServiceUtil.getCompanyGroups(companyId, QueryUtil.ALL_POS, QueryUtil.ALL_POS);
                for(Group group : groups) {
                    long groupId = group.getGroupId();
                    //Articles
                    List<JournalArticle> articles = JournalArticleLocalServiceUtil.getArticles(groupId, QueryUtil.ALL_POS, QueryUtil.ALL_POS);
                    for(JournalArticle article: articles) {
                        if(article.getModifiedDate().after(date01012019))  {
                            _log.info(article.getCreateDate() + " : " + article.getStructureId());

                            long articleGroupId = article.getGroupId();
                            long articleCompanyId = article.getCompanyId();
                            long userId = article.getUserId();
                            String userName = article.getUserName();
                            Date createDate = article.getCreateDate();
                            Date modifiedDate = article.getModifiedDate();
                            String className = article.getClassName();
                            long classPK = article.getClassPK();
                            int status = article.getStatus();
                            Date statusDate = article.getStatusDate();

                            item.setGroupId(articleGroupId);
                            item.setCompanyId(articleCompanyId);
                            item.setUserId(userId);
                            item.setUserName(userName);
                            item.setCreateDate(createDate);
                            item.setModifiedDate(modifiedDate);
                            item.setClassname_(className);
                            item.setClassPK(classPK);
                            item.setStatus(status);
                            item.setStatusDate(statusDate);
                            _log.info(item);

                        }
                    }
                }
            }

        } catch (SystemException e) {
            e.printStackTrace();
        } catch (ParseException e) {
            e.printStackTrace();
        }

        return item;

    }

}

<service-builder package-path="com.beorn.tm.synchro">

    <namespace>synchronizationAPI</namespace>

    <entity name="Item" uuid="true" local-service="true" remote-service="false">

        <!-- PK fields -->
        <column name="itemId" type="long" primary="true" />

        <!-- Group instance -->
        <column name="groupId" type="long" />

        <!-- Audit fields -->
        <column name="companyId" type="long" />
        <column name="userId" type="long" />
        <column name="userName" type="String" />
        <column name="createDate" type="Date" />
        <column name="modifiedDate" type="Date" />

        <!-- Other fields -->
        <column name="classname_" type="String" db-name="classname" />
        <column name="classPK" type="long" />
        <column name="status" type="int" />
        <column name="statusMessage" type="String" />
        <column name="statusDate" type="Date" />

        <!-- Order -->
        <order by="asc">
            <order-column name="createDate" />
        </order>

        <!-- Finder methods -->
        <finder name="CompanyId" return-type="Collection">
            <finder-column name="companyId" />
        </finder>
        <finder name="GroupId" return-type="Collection">
            <finder-column name="groupId" />
        </finder>
        <finder name="GroupIdAndClassName" return-type="Collection">
            <finder-column name="groupId" />
            <finder-column name="classname_" />
        </finder>
        <finder name="GroupIdAndClassNameAndStatus" return-type="Collection">
            <finder-column name="groupId" />
            <finder-column name="classname_" />
            <finder-column name="status" />
        </finder>

    </entity>

    <exceptions>
        <exception>StatusNotFound</exception>
    </exceptions>

</service-builder>

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