java - 无法将自定义类型作为 json 字符串存储到数据库中 - java.lang.IllegalArgumentException : Can not set final field to java. util.LinkedHashMap

Question

我在 JPA 实体中使用自定义类型，然后将其转换为 JSON 字符串并将其存储到数据库中时遇到问题。

这是基本的 JPA 实体:Discount(我们使用 Lombok 和构建器来创建对象实例。问题发生在 LocalizedTexts 类型的两个字段上):

@Value
@NoArgsConstructor(force = true)
@AllArgsConstructor
@Builder(builderMethodName = "internalBuilder")
@Entity
@Table(name="discount")
public class Discount {
    
    @Id
    @Column(name = "ID", nullable = false, unique = true)
    @Type(type="uuid-char")
    UUID id;
    
    @Column(name="NO", nullable = false, unique = true)
    String no;
    
    @Column(name="I_NO", nullable = false, unique = true)
    Integer iNo;
    
    @Convert(converter = JpaJsonConverter.class)
    @Column(name="DESIGNATION", nullable = false)
    LocalizedTexts designation;
    
    @Convert(converter = JpaJsonConverter.class)
    @Column(name="PRINT_TEXT")
    LocalizedTexts printText;
    
    ...

    /**
     * Builder with required parameters
     */
    public static Discount.DiscountBuilder builder(UUID id, String no, LocalizedTexts designation) {
        return internalBuilder()
                .id(id)
                .no(no)
                .designation(designation);
    }

    // Getters
    ...

}

我正在使用属性转换器来转换自定义类型(扩展 Map

@Converter
public class JpaJsonConverter implements AttributeConverter<Object, String> {

    private final static ObjectMapper objectMapper = new ObjectMapper();

    @Override
    public String convertToDatabaseColumn(Object localizedTexts) {
        String localizedTextsJson = null;
        try {
            localizedTextsJson = objectMapper.writeValueAsString(localizedTexts);
        } catch (JsonProcessingException ex) {
            //throw new RuntimeException();
        }
        return localizedTextsJson;
    }

    @Override
    public Object convertToEntityAttribute(String localizedTextsJSON) {
        Object localizedTexts = null;
        try {
            localizedTexts = objectMapper.readValue(localizedTextsJSON, Object.class);
        } catch (IOException ex) {
            //throw new RuntimeException();
        }
        return localizedTexts;
    }
}

这是自定义类型:LocalizedTexts (Map ):

public class LocalizedTexts extends HashMap<Language, String> implements EntityBase {
    public LocalizedTexts() {
    }

    public LocalizedTexts(Map map) {
        this.putAll(map);
    }

    public static LocalizedTextsBuilder internalBuilder() {
        return new LocalizedTextsBuilder();
    }

    public static class LocalizedTextsBuilder {
        LocalizedTextsBuilder() {
        }

        public LocalizedTexts build() {
            return new LocalizedTexts();
        }

        public String toString() {
            return "LocalizedTexts.LocalizedTextsBuilder()";
        }
    }
}

当我尝试将 Discount 对象保存到数据库中时出现问题:

...
discountRepository.save(discount);
...

我已经检查过，属性转换器按预期工作(将 LocalizedTexts 转换为 JSON 字符串)。我得到的异常的完整堆栈跟踪如下:

org.springframework.orm.jpa.JpaSystemException: Could not set field value [{de=Rabatt 1, en=Discount 1}] value by reflection : [class net.xxxxx.yyyyy.svc_voucher.entity.Discount.designation] setter of net.xxxxx.yyyyy.svc_voucher.entity.Discount.designation; nested exception is org.hibernate.PropertyAccessException: Could not set field value [{de=Rabatt 1, en=Discount 1}] value by reflection : [class net.xxxxx.yyyyy.svc_voucher.entity.Discount.designation] setter of net.xxxxx.yyyyy.svc_voucher.entity.Discount.designation

    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:331)
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:233)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:551)
    at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:61)
    at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:242)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:152)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:174)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215)
    at jdk.proxy2/jdk.proxy2.$Proxy116.save(Unknown Source)
    at net.xxxxx.yyyyy.svc_voucher.messagehandler.DiscountHandler.handleCommand(DiscountHandler.java:58)
    at net.xxxxx.yyyyy.svc_voucher.handlers.TestDiscountHandler.Sending_script_to_messageHandler_handleCommand(TestDiscountHandler.java:109)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:568)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74)
    at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
    at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
    at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
    at com.intellij.rt.junit.IdeaTestRunner$Repeater$1.execute(IdeaTestRunner.java:38)
    at com.intellij.rt.execution.junit.TestsRepeater.repeat(TestsRepeater.java:11)
    at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:35)
    at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
    at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: org.hibernate.PropertyAccessException: Could not set field value [{de=Rabatt 1, en=Discount 1}] value by reflection : [class net.xxxxx.yyyyy.svc_voucher.entity.Discount.designation] setter of net.xxxxx.yyyyy.svc_voucher.entity.Discount.designation
    at org.hibernate.property.access.spi.SetterFieldImpl.set(SetterFieldImpl.java:72)
    at org.hibernate.tuple.entity.AbstractEntityTuplizer.setPropertyValues(AbstractEntityTuplizer.java:681)
    at org.hibernate.tuple.entity.PojoEntityTuplizer.setPropertyValues(PojoEntityTuplizer.java:144)
    at org.hibernate.persister.entity.AbstractEntityPersister.setPropertyValues(AbstractEntityPersister.java:5252)
    at org.hibernate.event.internal.DefaultMergeEventListener.copyValues(DefaultMergeEventListener.java:498)
    at org.hibernate.event.internal.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:241)
    at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:318)
    at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:172)
    at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:70)
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:107)
    at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:829)
    at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:816)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:568)
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:311)
    at jdk.proxy2/jdk.proxy2.$Proxy113.merge(Unknown Source)
    at org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:650)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:568)
    at org.springframework.data.repository.core.support.RepositoryMethodInvoker$RepositoryFragmentMethodInvoker.lambda$new$0(RepositoryMethodInvoker.java:289)
    at org.springframework.data.repository.core.support.RepositoryMethodInvoker.doInvoke(RepositoryMethodInvoker.java:137)
    at org.springframework.data.repository.core.support.RepositoryMethodInvoker.invoke(RepositoryMethodInvoker.java:121)
    at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:529)
    at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:285)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:639)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:163)
    at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:138)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:80)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:123)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:388)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:137)
    ... 42 more
Caused by: java.lang.IllegalArgumentException: Can not set final net.xxxxx.yyyyy.entity.internal.LocalizedTexts field net.xxxxx.yyyyy.svc_voucher.entity.Discount.designation to java.util.LinkedHashMap
    at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)
    at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)
    at java.base/jdk.internal.reflect.UnsafeQualifiedObjectFieldAccessorImpl.set(UnsafeQualifiedObjectFieldAccessorImpl.java:83)
    at java.base/java.lang.reflect.Field.set(Field.java:799)
    at org.hibernate.property.access.spi.SetterFieldImpl.set(SetterFieldImpl.java:52)
    ... 81 more

Answer 1

起初，人们很容易相信 final修饰符是问题的原因，但实际上不是。

让我们尝试这个简单的测试:

import java.lang.reflect.Field;

class Discount
{
    private final Integer id = 0;
}

public class Test
{
    public static void main(String[] args) throws IllegalAccessException, NoSuchFieldException
    {
        Discount d = new Discount();
        Field f = Discount.class.getDeclaredField("id");
        f.set(d, 1);
    }
}

我们得到:

java.lang.IllegalAccessException: class Test cannot access a member of class Discount with modifiers "private final"

这不是您收到的错误(您的堆栈跟踪显示 IllegalArgumentException ，而不是 IllegalAccessException )。

让我们更改代码以添加 setAccessible(true) :

import java.lang.reflect.Field;

class Discount
{
    private final Integer id = 0;
}

public class Test
{
    public static void main(String[] args) throws IllegalAccessException, NoSuchFieldException
    {
        Discount d = new Discount();
        Field f = Discount.class.getDeclaredField("id");
        f.setAccessible(true);
        f.set(d, 1);
    }
}

这次成功了，没有抛出异常。

现在让我们替换 1与 "1" :

import java.lang.reflect.Field;

class Discount
{
    private final Integer id = 0;
}

public class Test
{
    public static void main(String[] args) throws IllegalAccessException, NoSuchFieldException
    {
        Discount d = new Discount();
        Field f = Discount.class.getDeclaredField("id");
        f.setAccessible(true);
        f.set(d, "1");
    }
}

我们得到:

java.lang.IllegalArgumentException: Can not set final java.lang.Integer field Discount.id to java.lang.String

这次和你的错误完全一样。 IllegalArgumentException意味着我们正在尝试分配一个不兼容的值(此处为 String 到 Integer )。

您的堆栈跟踪表明您正在尝试分配 LinkedHashMap到designation字段，这确实不兼容( designation 是 LocalizedTexts )。

了解LinkedHashMap在哪里来自，我们来看看你的JpaJsonConverter 。负责将 JSON 字符串转换为 LocalizedTexts 的方法对象是:

public Object convertToEntityAttribute(String localizedTextsJSON) {
    Object localizedTexts = null;
    try {
        localizedTexts = objectMapper.readValue(localizedTextsJSON, Object.class);
    } catch (IOException ex) {
        //throw new RuntimeException();
    }
    return localizedTexts;
}

您正在调用 readValue()包含一个对象的 JSON 字符串，以及 Object.class作为第二个参数。在这种情况下， jackson 返回 LinkedHashMap 。它无法知道您想要 LocalizedTexts .

以下是修复该方法的可能方法:

@SuppressWarnings("unchecked")
public Object convertToEntityAttribute(String localizedTextsJSON) {
    LocalizedTexts localizedTexts = new LocalizedTexts();
    try {
        Map<String,String> map = (Map<String,String>)objectMapper.readValue(localizedTextsJSON, Object.class);
        for(Map.Entry<String,String> e : map.entrySet())
            localizedTexts.put(Language.valueOf(e.getKey()), e.getValue());
    } catch (IOException ex) {
        throw new RuntimeException(ex);
    }
    return localizedTexts;
}