java - Spring 数据jdbc。无法为枚举添加自定义转换器

Question

我想将枚举作为我实体的字段。

我的申请是这样的:

Spring 启动版本

plugins {
        id 'org.springframework.boot' version '2.6.2' apply false

存储库:

@Repository
public interface MyEntityRepository extends PagingAndSortingRepository<MyEntity, UUID> {
 ...

实体:

@Table("my_entity")
public class MyEntity{
   ...
   private FileType fileType;
  // get + set
}

枚举声明:

public enum FileType {
    TYPE_1(1),
    TYPE_2(2);

    int databaseId;

    public static FileType byDatabaseId(Integer databaseId){
        return Arrays.stream(values()).findFirst().orElse(null);
    }
    FileType(int databaseId) {
        this.databaseId = databaseId;
    }

    public int getDatabaseId() {
        return databaseId;
    }
}

我的尝试:

我找到了以下答案并尝试遵循它:https://stackoverflow.com/a/53296199/2674303

所以我添加了bean

@Bean
public JdbcCustomConversions jdbcCustomConversions() {
    return new JdbcCustomConversions(asList(new DatabaseIdToFileTypeConverter(), new FileTypeToDatabaseIdConverter()));
}

转换器:

@WritingConverter
public class FileTypeToDatabaseIdConverter implements Converter<FileType, Integer> {
    @Override
    public Integer convert(FileType source) {
        return source.getDatabaseId();
    }
}

@ReadingConverter
public class DatabaseIdToFileTypeConverter implements Converter<Integer, FileType> {
    @Override
    public FileType convert(Integer databaseId) {
        return FileType.byDatabaseId(databaseId);
    }
}

但我看到错误:

The bean 'jdbcCustomConversions', defined in class path resource[org/springframework/boot/autoconfigure/data/jdbc/JdbcRepositoriesAutoConfiguration$SpringBootJdbcConfiguration.class],could not be registered. A bean with that name has already beendefined in my.pack.Main and overriding is disabled.

我尝试将方法 jdbcCustomConversions() 重命名为 myJdbcCustomConversions()。它有助于避免上述错误，但在实体持久性期间未调用转换器，我看到另一个错误，即应用程序尝试保存字符串但数据库类型为 bigint。

20:39:10.689  DEBUG  [main] o.s.jdbc.core.StatementCreatorUtils: JDBC getParameterType call failed - using fallback method instead: org.postgresql.util.PSQLException: ERROR: column "file_type" is of type bigint but expression is of type character varying
  Hint: You will need to rewrite or cast the expression.
  Position: 174 

我还尝试使用最新(当前)版本的 spring boot:

id 'org.springframework.boot' version '2.6.2' apply false

但这并没有帮助。

我错过了什么？如何正确地将枚举映射到整数列？

附言

我使用以下代码进行测试:

@SpringBootApplication
@EnableJdbcAuditing
@EnableScheduling
public class Main {
    public static void main(String[] args) {
        ConfigurableApplicationContext applicationContext = SpringApplication.run(Main.class, args);
        MyEntityRepositoryrepository = applicationContext.getBean(MyEntityRepository.class);
        MyEntity entity =  new MyEntity();
        ...
        entity.setFileType(FileType.TYPE_2);
        repository.save(entity);
    }

    @Bean
    public ModelMapper modelMapper() {
        ModelMapper mapper = new ModelMapper();
        mapper.getConfiguration()
                .setMatchingStrategy(MatchingStrategies.STRICT)
                .setFieldMatchingEnabled(true)
                .setSkipNullEnabled(true)
                .setFieldAccessLevel(PRIVATE);
        return mapper;
    }


    @Bean
    public AbstractJdbcConfiguration jdbcConfiguration() {
        return new MySpringBootJdbcConfiguration();
    }
    @Configuration
    static class MySpringBootJdbcConfiguration extends AbstractJdbcConfiguration {
        @Override
        protected List<?> userConverters() {
            return asList(new DatabaseIdToFileTypeConverter(), new FileTypeToDatabaseIdConverter());
        }
    }
}

更新

我的代码是:

@SpringBootApplication
@EnableJdbcAuditing
@EnableScheduling
public class Main {

    public static void main(String[] args) {
        ConfigurableApplicationContext applicationContext = SpringApplication.run(Main.class, args);
        MyEntityRepositoryrepository = applicationContext.getBean(MyEntityRepository.class);
        MyEntity entity =  new MyEntity();
        ...
        entity.setFileType(FileType.TYPE_2);
        repository.save(entity);
    }

    @Bean
    public ModelMapper modelMapper() {
        ModelMapper mapper = new ModelMapper();
        mapper.getConfiguration()
                .setMatchingStrategy(MatchingStrategies.STRICT)
                .setFieldMatchingEnabled(true)
                .setSkipNullEnabled(true)
                .setFieldAccessLevel(PRIVATE);
        return mapper;
    }

    @Bean
    public AbstractJdbcConfiguration jdbcConfiguration() {
        return new MySpringBootJdbcConfiguration();
    }

    @Configuration
    static class MySpringBootJdbcConfiguration extends AbstractJdbcConfiguration {
        @Override
        protected List<?> userConverters() {
            return asList(new DatabaseIdToFileTypeConverter(), new FileTypeToDatabaseIdConverter());
        }

        @Bean
        public JdbcConverter jdbcConverter(JdbcMappingContext mappingContext,
                                           NamedParameterJdbcOperations operations,
                                           @Lazy RelationResolver relationResolver,
                                           JdbcCustomConversions conversions,
                                           Dialect dialect) {

            JdbcArrayColumns arrayColumns = dialect instanceof JdbcDialect ? ((JdbcDialect) dialect).getArraySupport()
                    : JdbcArrayColumns.DefaultSupport.INSTANCE;
            DefaultJdbcTypeFactory jdbcTypeFactory = new DefaultJdbcTypeFactory(operations.getJdbcOperations(),
                    arrayColumns);

            return new MyJdbcConverter(
                    mappingContext,
                    relationResolver,
                    conversions,
                    jdbcTypeFactory,
                    dialect.getIdentifierProcessing()
            );
        }
    }

    static class MyJdbcConverter extends BasicJdbcConverter {
        MyJdbcConverter(
                MappingContext<? extends RelationalPersistentEntity<?>, ? extends RelationalPersistentProperty> context,
                RelationResolver relationResolver,
                CustomConversions conversions,
                JdbcTypeFactory typeFactory,
                IdentifierProcessing identifierProcessing) {
            super(context, relationResolver, conversions, typeFactory, identifierProcessing);
        }

        @Override
        public int getSqlType(RelationalPersistentProperty property) {
            if (FileType.class.equals(property.getActualType())) {
                return Types.BIGINT;
            } else {
                return super.getSqlType(property);
            }
        }

        @Override
        public Class<?> getColumnType(RelationalPersistentProperty property) {
            if (FileType.class.equals(property.getActualType())) {
                return Long.class;
            } else {
                return super.getColumnType(property);
            }
        }
    }
}

但我遇到错误:

Caused by: org.postgresql.util.PSQLException: Cannot convert an instance of java.lang.String to type long
    at org.postgresql.jdbc.PgPreparedStatement.cannotCastException(PgPreparedStatement.java:925)
    at org.postgresql.jdbc.PgPreparedStatement.castToLong(PgPreparedStatement.java:810)
    at org.postgresql.jdbc.PgPreparedStatement.setObject(PgPreparedStatement.java:561)
    at org.postgresql.jdbc.PgPreparedStatement.setObject(PgPreparedStatement.java:931)
    at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.setObject(HikariProxyPreparedStatement.java)
    at org.springframework.jdbc.core.StatementCreatorUtils.setValue(StatementCreatorUtils.java:414)
    at org.springframework.jdbc.core.StatementCreatorUtils.setParameterValueInternal(StatementCreatorUtils.java:231)
    at org.springframework.jdbc.core.StatementCreatorUtils.setParameterValue(StatementCreatorUtils.java:146)
    at org.springframework.jdbc.core.PreparedStatementCreatorFactory$PreparedStatementCreatorImpl.setValues(PreparedStatementCreatorFactory.java:283)
    at org.springframework.jdbc.core.PreparedStatementCreatorFactory$PreparedStatementCreatorImpl.createPreparedStatement(PreparedStatementCreatorFactory.java:241)
    at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:649)
    ... 50 more
Caused by: java.lang.NumberFormatException: For input string: "TYPE_2"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Long.parseLong(Long.java:589)
    at java.lang.Long.parseLong(Long.java:631)
    at org.postgresql.jdbc.PgPreparedStatement.castToLong(PgPreparedStatement.java:792)
    ... 59 more

Answer 1

请尝试以下操作:

@Bean
public AbstractJdbcConfiguration jdbcConfiguration() {
    return new MySpringBootJdbcConfiguration();
}

@Configuration
static class MySpringBootJdbcConfiguration extends AbstractJdbcConfiguration {
    @Override
    protected List<?> userConverters() {
        return List.of(new DatabaseIdToFileTypeConverter(), new FileTypeToDatabaseIdConverter());
    }
}

解释:

Spring 提示 JdbcCustomConversions在自动配置类中已经定义(由您的 bean)并且您没有启用 bean 覆盖。

JdbcRepositoriesAutoConfiguration已经改变了几次，在 Spring 2.6.2 中有:

@Configuration(proxyBeanMethods = false)
@ConditionalOnMissingBean(AbstractJdbcConfiguration.class)
static class SpringBootJdbcConfiguration extends AbstractJdbcConfiguration {

}

反过来，AbstractJdbcConfiguration有:

@Bean
public JdbcCustomConversions jdbcCustomConversions() {

    try {

        Dialect dialect = applicationContext.getBean(Dialect.class);
        SimpleTypeHolder simpleTypeHolder = dialect.simpleTypes().isEmpty() ? JdbcSimpleTypes.HOLDER
                : new SimpleTypeHolder(dialect.simpleTypes(), JdbcSimpleTypes.HOLDER);

        return new JdbcCustomConversions(
                CustomConversions.StoreConversions.of(simpleTypeHolder, storeConverters(dialect)), userConverters());

    } catch (NoSuchBeanDefinitionException exception) {

        LOG.warn("No dialect found. CustomConversions will be configured without dialect specific conversions.");

        return new JdbcCustomConversions();
    }
}

如您所见，JdbcCustomConversions无论如何都不是有条件的，所以定义你自己的会引起冲突。幸运的是，它提供了一个扩展点 userConverters()可以覆盖它以提供您自己的转换器。

更新

正如评论中所讨论的:

• FileType.byDatabaseId坏了——它忽略了它的输入参数

• 因为 db 中的列类型是 BIGINT，您的转换器必须从 Long 转换，而不是从 Integer 转换，这解决了读取查询问题

• 对于写入，有一个 Unresolved 错误 https://github.com/spring-projects/spring-data-jdbc/issues/629有一个硬编码的假设，即枚举被转换为字符串，并且只检查枚举 -> 字符串转换器。由于我们要转换为 Long，因此我们需要对 BasicJdbcConverter 进行修改通过对其进行子类化并将子类化转换器注册为 @Bean .

你需要覆盖两个方法

• public int getSqlType(RelationalPersistentProperty property)
• public Class<?> getColumnType(RelationalPersistentProperty property)

我对 Enum 类型和相应的列类型进行了硬编码，但您可能希望更喜欢它。

@Bean
public AbstractJdbcConfiguration jdbcConfiguration() {
    return new MySpringBootJdbcConfiguration();
}

@Configuration
static class MySpringBootJdbcConfiguration extends AbstractJdbcConfiguration {
    @Override
    protected List<?> userConverters() {
        return List.of(new DatabaseIdToFileTypeConverter(), new FileTypeToDatabaseIdConverter());
    }

    @Bean
    public JdbcConverter jdbcConverter(JdbcMappingContext mappingContext,
                                       NamedParameterJdbcOperations operations,
                                       @Lazy RelationResolver relationResolver,
                                       JdbcCustomConversions conversions,
                                       Dialect dialect) {

        JdbcArrayColumns arrayColumns = dialect instanceof JdbcDialect ? ((JdbcDialect) dialect).getArraySupport()
                : JdbcArrayColumns.DefaultSupport.INSTANCE;
        DefaultJdbcTypeFactory jdbcTypeFactory = new DefaultJdbcTypeFactory(operations.getJdbcOperations(),
                arrayColumns);

        return new MyJdbcConverter(
                mappingContext,
                relationResolver,
                conversions,
                jdbcTypeFactory,
                dialect.getIdentifierProcessing()
        );
    }
}

static class MyJdbcConverter extends BasicJdbcConverter {
    MyJdbcConverter(
            MappingContext<? extends RelationalPersistentEntity<?>, ? extends RelationalPersistentProperty> context,
            RelationResolver relationResolver,
            CustomConversions conversions,
            JdbcTypeFactory typeFactory,
            IdentifierProcessing identifierProcessing) {
        super(context, relationResolver, conversions, typeFactory, identifierProcessing);
    }

    @Override
    public int getSqlType(RelationalPersistentProperty property) {
        if (FileType.class.equals(property.getActualType())) {
            return Types.BIGINT;
        } else {
            return super.getSqlType(property);
        }
    }

    @Override
    public Class<?> getColumnType(RelationalPersistentProperty property) {
        if (FileType.class.equals(property.getActualType())) {
            return Long.class;
        } else {
            return super.getColumnType(property);
        }
    }
}