彈簧資料jdbc。無法為列舉添加自定義轉換器-有解無憂

我想將列舉作為我的物體的欄位。

我的應用程式看起來像：

春季啟動版

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

存盤庫：

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

物體：

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

列舉宣告：

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;
    }
}

我的嘗試：

我找到了以下答案并嘗試關注它：https ://stackoverflow.com/a/53296199/2674303

所以我加了豆

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

轉換器：

@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);
    }
}

但我看到錯誤：

無法注冊在類路徑資源 [org/springframework/boot/autoconfigure/data/jdbc/JdbcRepositoriesAutoConfiguration$SpringBootJdbcConfiguration.class] 中定義的 bean 'jdbcCustomConversions'。已在 my.pack.Main 中定義了具有該名稱的 bean，并且禁用了覆寫。

我試圖將方法重命名jdbcCustomConversions()為myJdbcCustomConversions(). 它有助于避免上述錯誤，但在物體持久性期間未呼叫轉換器，我看到另一個錯誤，即應用程式嘗試保存 String 但資料庫型別為 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

我還嘗試使用最新（當前）版本的 spring boot：

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

但這沒有幫助。

我錯過了什么？如何正確地將列舉映射到整數列？

附言

我使用以下代碼進行測驗：

@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

我的代碼是：

@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);
            }
        }
    }
}

但我遇到錯誤：

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

uj5u.com熱心網友回復：

請嘗試以下操作：

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

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

解釋：

Spring 抱怨JdbcCustomConversions在自動配置類中已經定義（由您的 bean）并且您沒有啟用 bean 覆寫。

JdbcRepositoriesAutoConfiguration 已經改變了幾次，在 Spring 2.6.2 中它有：

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

}

反過來，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();
    }
}

如您所見，JdbcCustomConversions它不是以任何方式有條件的，因此定義您自己的會導致沖突。幸運的是，它提供了一個擴展點userConverters()，可以覆寫它以提供您自己的轉換器。

更新

正如評論中所討論的：

FileType.byDatabaseId 壞了 - 它忽略了它的輸入引數
由于 db 中的列型別是 BIGINT，因此您的轉換器必須從 Long 轉換，而不是 Integer，這解決了讀取查詢
對于寫入，有一個打開的錯誤https://github.com/spring-projects/spring-data-jdbc/issues/629有一個硬編碼的假設，即列舉被轉換為字串，并且只檢查 Enum -> 字串轉換器. 由于我們要轉換為 Long，我們需要對其進行修改，將BasicJdbcConverter其子類化并將子類化轉換器注冊為@Bean.

您需要覆寫兩個方法

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

我對 Enum 型別和相應的列型別進行了硬編碼，但您可能想要更喜歡它。

@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);
        }
    }
}

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