获取ClassCastException：将Map <string，boolean =“”>持久保存到数据库时，无法将java.lang.String强制转换为java.lang.Boolean

Question

我正在使用Spring MVC，并尝试保存一个基本调查表，对Map<String, Boolean>的是/否（是/否）答案，其中String键分别为“ Q1”和“ Q2”。

在控制器端，它正确绑定，将各自的输入值设置为Map，但是当实体对象传递给服务进行保存时，抛出ClassCastException，抱怨无法保存。数据库（postgres）类型为布尔值。

例外

java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Boolean
    at org.hibernate.type.descriptor.java.BooleanTypeDescriptor.unwrap(BooleanTypeDescriptor.java:19) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.type.descriptor.sql.BooleanTypeDescriptor$1.doBind(BooleanTypeDescriptor.java:44) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.type.descriptor.sql.BasicBinder.bind(BasicBinder.java:74) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:280) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:275) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.type.AbstractSingleColumnStandardBasicType.nullSafeSet(AbstractSingleColumnStandardBasicType.java:39) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.persister.collection.AbstractCollectionPersister.writeElement(AbstractCollectionPersister.java:903) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.persister.collection.BasicCollectionPersister.doUpdateRows(BasicCollectionPersister.java:231) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.persister.collection.AbstractCollectionPersister.updateRows(AbstractCollectionPersister.java:1728) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]

实体

@Entity
public class Questionnaire {
    private static final long serialVersionUID = 1L;
    public static final String[] SHORT_QUESTIONS = {"q1", "q2", "q3", "q4", "q5", "q6", "q7"};

    @ElementCollection(fetch=FetchType.LAZY)
    @MapKeyColumn(name="question")
    @Column(name="answer")
    private Map<String, Boolean> shortForm = new LinkedHashMap<>();

    // constructor, setters and getters here
}

控制器方法：

@PostMapping("/questionnaire/save/{id}")
public String save(@ModelAttribute @Valid Questionnaire questionnaire, BindingResult binder, RedirectAttributes redirectAttrs, Model model) {
    if (binder.hasErrors()) {
        model.addAttribute("messageDanger", messages.getMessage("general.save.failed", null, LocaleContextHolder.getLocale()));
        return "questionnaire/full";
    }

    // these all bind properly and return true or false accordingly
    log.debug("q1: " + questionnaire.getShortForm().get("q1"));
    log.debug("q2: " + questionnaire.getShortForm().get("q2"));
    log.debug("q3: " + questionnaire.getShortForm().get("q3"));
    log.debug("q4: " + questionnaire.getShortForm().get("q4"));
    log.debug("q5: " + questionnaire.getShortForm().get("q5"));
    log.debug("q6: " + questionnaire.getShortForm().get("q6"));

    // Exception occurs here during .save()
    questionnaireSvc.save(questionnaire);

    redirectAttrs.addFlashAttribute("message", messages.getMessage("general.save.success", null, LocaleContextHolder.getLocale()));
    return "redirect:/questionnaire/full/" + questionnaire.getId();
}

HTML（Thymeleaf）

<tr th:each="question : ${T(app.model.Questionnaire).SHORT_QUESTIONS}">
    <td headers="question-col" th:utext="#{questionnaire.short.__${question}__}"></td>
    <td headers="applicant-col">
    <div class="custom-control custom-radio">
        <input type="radio" th:field="*{shortForm[__${question}__]}" class="custom-control-input" required value="false" />
        <label class="custom-control-label" th:text="#{general.no}" th:for="${#ids.prev('shortForm__${question}__')}"></label>
    </div>
    <div class="custom-control custom-radio">
        <input type="radio" th:field="*{shortForm[__${question}__]}" class="custom-control-input" required value="true" />
        <label class="custom-control-label" th:text="#{general.yes}" th:for="${#ids.prev('shortForm__${question}__')}"></label>
    </div>
</td>