Hibernate 给出了一个奇怪的 ClassCast 异常（使用 Transformers）

Question

此代码：

@Override
public List<FactCodeDto> getAllFactsWithoutParentsAsFactDto() {
    String completeQuery = FactCodeQueries.SELECT_DTO_FROM_FACT_WITH_NO_PARENTS;
    Query query = createHibernateQueryForUnmappedTypeFactDto(completeQuery);

    List<FactCodeDto> factDtoList = query.list(); //line 133
    return factDtoList;
}

调用此方法：

private Query createHibernateQueryForUnmappedTypeFactDto(String sqlQuery) throws HibernateException {
    return FactCodeQueries.addScalars(createSQLQuery(sqlQuery)).setResultTransformer(Transformers.aliasToBean(FactCodeDto.class));
}

给我一个 ClassCastException -> 跟踪的一部分：

Caused by: java.lang.ClassCastException: org.bamboomy.cjr.dto.FactCodeDto cannot be cast to java.util.Map
    at org.hibernate.property.access.internal.PropertyAccessMapImpl$SetterImpl.set(PropertyAccessMapImpl.java:102)
    at org.hibernate.transform.AliasToBeanResultTransformer.transformTuple(AliasToBeanResultTransformer.java:78)
    at org.hibernate.hql.internal.HolderInstantiator.instantiate(HolderInstantiator.java:75)
    at org.hibernate.loader.custom.CustomLoader.getResultList(CustomLoader.java:435)
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2423)
    at org.hibernate.loader.Loader.list(Loader.java:2418)
    at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:336)
    at org.hibernate.internal.SessionImpl.listCustomQuery(SessionImpl.java:1898)
    at org.hibernate.internal.AbstractSessionImpl.list(AbstractSessionImpl.java:318)
    at org.hibernate.internal.SQLQueryImpl.list(SQLQueryImpl.java:125)
    at org.bamboomy.cjr.dao.factcode.FactCodeDAOImpl.getAllFactsWithoutParentsAsFactDto(FactCodeDAOImpl.java:133)

这很奇怪，因为实际上，如果您查找 Hibernate 的源代码，它会尝试这样做：

@Override
@SuppressWarnings("unchecked")
public void set(Object target, Object value, SessionFactoryImplementor factory) {
    ( (Map) target ).put( propertyName, value ); //line 102
}

这没有任何意义...

target 是 Class 类型，此代码尝试将其转换为 Map，

为什么要这么做？？？

欢迎任何指点...

我正在使用 Hibernate 5（并且正在从 3 升级）...

编辑：我也使用 Spring（4.2.1.RELEASE；也在升级），它在部署时调用这些方法，也欢迎任何调试指针...

编辑 2：（根据要求将整个 FactCodeD 改为 class）

package org.bamboomy.cjr.dto;

import org.bamboomy.cjr.model.FactCode;
import org.bamboomy.cjr.model.FactCodeType;
import org.bamboomy.cjr.utility.FullDateUtil;
import org.bamboomy.cjr.utility.Locales;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;
import org.springframework.util.Assert;

import java.util.*;

@Getter
@Setter
@ToString
public class FactCodeDto extends TreeNodeValue {

    private String cdFact;
    private String cdFactSuffix;
    private Boolean isSupplementCode;
    private Boolean isTitleCode;
    private Boolean mustBeFollowed;

    private Date activeFrom;
    private Date activeTo;
    private Boolean isCode;
    private Long idFact;
    private Long idParent;
    private String type;
    Map<Locale, String> description = new HashMap<Locale, String>(3);

    public FactCodeDto() {
    }

    public FactCodeDto(String prefix, String suffix) {
        super();
        this.cdFact = prefix;
        this.cdFactSuffix = suffix;
    }

    public FactCodeDto(String cdFact, String cdFactSuffix, Boolean isSupplementCode,  Boolean mustBeFollowed) {
        super();
        this.cdFact = cdFact;
        this.cdFactSuffix = cdFactSuffix;
        this.isSupplementCode = isSupplementCode;
        this.mustBeFollowed = mustBeFollowed;

    }

    public FactCodeDto(String cdFact, String cdFactSuffix, Boolean isSupplementCode,  Boolean mustBeFollowed, Long idFact, Long idParent, Boolean isCode, Boolean isTitleCode, Date from, Date to, Map<Locale, String> descriptions,String type) {
        super();
        this.cdFact = cdFact;
        this.cdFactSuffix = cdFactSuffix;
        this.isSupplementCode = isSupplementCode;
        this.mustBeFollowed = mustBeFollowed;
        this.idFact = idFact;
        this.idParent = idParent;
        this.isCode = isCode;
        this.isTitleCode = isTitleCode;
        this.activeFrom = from;
        this.activeTo = to;
        if (descriptions != null) {
            this.description = descriptions;
        }

        this.type = type;

    }

    public FactCodeDto(FactCode fc) {
        this(fc.getPrefix(), fc.getSuffix(), fc.isSupplementCode(), fc.isHasMandatorySupplCodes(), fc.getId(), fc.getParent(), fc.isActualCode(), fc.isTitleCode(), fc.getActiveFrom(), fc.getActiveTo(), fc.getAllDesc(),fc.getType().getCode());
    }

    public String formatCode() {
        return FactCode.formatCode(cdFact, cdFactSuffix);
    }

    public boolean isActive() {
        Date now = new Date(System.currentTimeMillis());
        return FullDateUtil.isBetweenDates(now, this.activeFrom, this.activeTo);

    }

    public void setDescFr(String s) {
        description.put(Locales.FRENCH, s);
    }

    public void setDescNl(String s) {
        description.put(Locales.DUTCH, s);
    }

    public void setDescDe(String s) {
        description.put(Locales.GERMAN, s);
    }

    /**
     * public String toString() {
     * StringBuilder sb = new StringBuilder();
     * sb.append(getIdFact() + ": ")
     * .append(getIdParent() + ": ")
     * .append(" " + cdFact + cdFactSuffix + ": " + (isSupplementCode ? "NO Principal " : "   Principal "))
     * .append((mustBeFollowed ? "    Must Be Followed " : "NOT Must Be Followed "));
     * return sb.toString();
     * }
     */

    public Map<Locale, String> getDescription() {
        return description;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        String fullCode = formatCode();
        result = prime * result + ((fullCode == null) ? 0 : fullCode.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        FactCodeDto other = (FactCodeDto) obj;

        return formatCode().equals(other.formatCode());
    }

    @Override
    public boolean isChildOf(TreeNodeValue value) {
        Assert.notNull(value);
        boolean isChild = false;
        if (value instanceof FactCodeDto) {
            if (this.getIdParent() != null) {
                isChild = this.getIdParent().equals(((FactCodeDto) value).getIdFact());
            }

        }
        return isChild;
    }

    @Override
    public boolean isBrotherOf(TreeNodeValue value) {
        Assert.notNull(value);
        boolean isBrother = false;
        if (value instanceof FactCodeDto) {
            if (this.getIdParent() != null) {
                isBrother = this.getIdParent().equals(((FactCodeDto) value).getIdParent());
            }

        }
        return isBrother;
    }

    @Override
    public boolean isParentOf(TreeNodeValue value) {
        Assert.notNull(value);
        boolean isParent = false;
        if (value instanceof FactCodeDto) {
            isParent = this.getIdFact().equals(((FactCodeDto) value).getIdParent());
        }
        return isParent;
    }


    @Override
    public int compareTo(TreeNodeValue to) {
        if (to instanceof FactCodeDto) {
            return formatCode().compareTo(((FactCodeDto) to).formatCode());
        } else return 1;

    }


    public String getCode() {
        return formatCode();
    }


}

Answer 1

最后找到解决方案并不难，

我刚刚创建了自己的（自定义）ResultTransformer 并在 setResultTransformer 方法中指定了它：

private Query createHibernateQueryForUnmappedTypeFactDto(String sqlQuery) throws HibernateException {
    return FactCodeQueries.addScalars(createSQLQuery(sqlQuery)).setResultTransformer(new FactCodeDtoResultTransformer());
    //return FactCodeQueries.addScalars(createSQLQuery(sqlQuery)).setResultTransformer(Transformers.aliasToBean(FactCodeDto.class));
}

自定义结果转换器代码：

package org.bamboomy.cjr.dao.factcode;

import org.bamboomy.cjr.dto.FactCodeDto;

import java.util.Date;
import java.util.List;

/**
 * Created by a162299 on 3-11-2015.
 */
public class FactCodeDtoResultTransformer implements org.hibernate.transform.ResultTransformer {

    @Override
    public Object transformTuple(Object[] objects, String[] strings) {

        FactCodeDto result = new FactCodeDto();

        for (int i = 0; i < objects.length; i++) {
            setField(result, strings[i], objects[i]);
        }

        return result;
    }

    private void setField(FactCodeDto result, String string, Object object) {

        if (string.equalsIgnoreCase("cdFact")) {
            result.setCdFact((String) object);
        } else if (string.equalsIgnoreCase("cdFactSuffix")) {
            result.setCdFactSuffix((String) object);
        } else if (string.equalsIgnoreCase("isSupplementCode")) {
            result.setIsSupplementCode((Boolean) object);
        } else if (string.equalsIgnoreCase("isTitleCode")) {
            result.setIsTitleCode((Boolean) object);
        } else if (string.equalsIgnoreCase("mustBeFollowed")) {
            result.setMustBeFollowed((Boolean) object);
        } else if (string.equalsIgnoreCase("activeFrom")) {
            result.setActiveFrom((Date) object);
        } else if (string.equalsIgnoreCase("activeTo")) {
            result.setActiveTo((Date) object);
        } else if (string.equalsIgnoreCase("descFr")) {
            result.setDescFr((String) object);
        } else if (string.equalsIgnoreCase("descNl")) {
            result.setDescNl((String) object);
        } else if (string.equalsIgnoreCase("descDe")) {
            result.setDescDe((String) object);
        } else if (string.equalsIgnoreCase("type")) {
            result.setType((String) object);
        } else if (string.equalsIgnoreCase("idFact")) {
            result.setIdFact((Long) object);
        } else if (string.equalsIgnoreCase("idParent")) {
            result.setIdParent((Long) object);
        } else if (string.equalsIgnoreCase("isCode")) {
            result.setIsCode((Boolean) object);
        } else {
            throw new RuntimeException("unknown field");
        }

    }

    @Override
    public List transformList(List list) {
        return list;
    }
}

在 hibernate 3 中，您可以将 Aliasses 设置为查询，但在 hibernate 5 中不能再这样做（如果我错了请纠正我）因此 aliasToBean 是您只能在实际使用别名时使用的东西；我没有，因此例外。

Answer 2

我发现 AliasToBean 在 Hibernate 5 中发生了变化。对我来说，为我的字段添加 getter 解决了这个问题。

Answer 3

我对这个问题做了一些调查。问题是 Hibernate 将列名的别名转换为大写 — cdFact 变为 CDFACT.

阅读此处以获得更深入的解释和解决方法： mapping Hibernate query results to custom class?

Answer 4

我遇到了这个异常

我将 DTO 中的一个字段命名为“closedIndexValue”，然后将其更改为“closedindexValue”，代码正常工作fine.I 认为这是由于字母 "I" 的大小写。

closedIndexValue -> 不正确的驼峰式 closedindexValue -> 正确的驼峰式

休眠版本：- 5.2.4

Answer 5

当 setters 和 getters 未正确映射到列名时，会发生此异常。确保您拥有正确的查询获取器和设置器（正确的名称和正确的数据类型）。在这里阅读更多相关信息：

http://javahonk.com/java-lang-classcastexception-com-wfs-otc-datamodels-imagineexpirymodel-cannot-cast-java-util-map/

Answer 6

我的情况是：

 => write sql query and try to map result to Class List 
 => Use "Transformers.aliasToBean" 
 => get Error "cannot be cast to java.util.Map"

解决方案：

      => just put \" before and after query aliases 
      ex: 
      "select first_name as \"firstName\" from test"

问题是 Hibernate 将列名的别名转换为大写或小写

Answer 7

我通过定义自己的自定义转换器解决了这个问题，如下所示 -

import org.hibernate.transform.BasicTransformerAdapter;   

public class FluentHibernateResultTransformer extends BasicTransformerAdapter {

    private static final long serialVersionUID = 6825154815776629666L;

    private final Class<?> resultClass;

    private NestedSetter[] setters;

    public FluentHibernateResultTransformer(Class<?> resultClass) {
        this.resultClass = resultClass;
    }

    @Override
    public Object transformTuple(Object[] tuple, String[] aliases) {
        createCachedSetters(resultClass, aliases);

        Object result = ClassUtils.newInstance(resultClass);

        for (int i = 0; i < aliases.length; i++) {
            setters[i].set(result, tuple[i]);
        }

        return result;
    }

    private void createCachedSetters(Class<?> resultClass, String[] aliases) {
        if (setters == null) {
            setters = createSetters(resultClass, aliases);
        }
    }

    private static NestedSetter[] createSetters(Class<?> resultClass, String[] aliases) {
        NestedSetter[] result = new NestedSetter[aliases.length];

        for (int i = 0; i < aliases.length; i++) {
            result[i] = NestedSetter.create(resultClass, aliases[i]);
        }

        return result;
    }
}

并在存储库方法中使用这种方式 -

@Override
    public List<WalletVO> getWalletRelatedData(WalletRequest walletRequest,
            Set<String> requiredVariablesSet) throws GenericBusinessException {
        String query = getWalletQuery(requiredVariablesSet);

        try {
            if (query != null && !query.isEmpty()) {
                SQLQuery sqlQuery = mEntityManager.unwrap(Session.class).createSQLQuery(query);
                return sqlQuery.setResultTransformer(new FluentHibernateResultTransformer(WalletVO.class))
                        .list();
            }
        } catch (Exception ex) {
            exceptionThrower.throwDatabaseException(null, false);
        }

        return Collections.emptyList();
    }

它完美运行！！！

Answer 8

尝试将列名和字段名都用大写字母。

Answer 9

当您在 AliasToBeanResultTransformer 中指定的 class 对应的列没有 getter 时，会出现此异常。尽管来自休眠的异常详细信息具有误导性。

Hibernate 给出了一个奇怪的 ClassCast 异常（使用 Transformers）

Hibernate gives a strange ClassCast exception (using Transformers)

java

spring

hibernate

hibernate-5.x