我如何使用杰克逊JSON映射与Java 8 LocalDateTime?
jsonmappingexception:不能实例化类型[简单类型,java.time类]的值。LocalDateTime] from JSON字符串;没有单字符串构造函数/工厂方法(通过引用链:MyDTO["field1"]->SubDTO["date"])
我如何使用杰克逊JSON映射与Java 8 LocalDateTime?
jsonmappingexception:不能实例化类型[简单类型,java.time类]的值。LocalDateTime] from JSON字符串;没有单字符串构造函数/工厂方法(通过引用链:MyDTO["field1"]->SubDTO["date"])
当前回答
如果您因为GraphQL Java工具而遇到此问题,并试图从日期字符串编组Java Instant,则需要设置SchemaParser以使用具有特定配置的ObjectMapper:
在GraphQLSchemaBuilder类中,注入ObjectMapper并添加以下模块:
ObjectMapper objectMapper =
new ObjectMapper().registerModule(new JavaTimeModule())
.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
并将其添加到选项中:
final SchemaParserOptions options = SchemaParserOptions.newOptions()
.objectMapperProvider(fieldDefinition -> objectMapper)
.typeDefinitionFactory(new YourTypeDefinitionFactory())
.build();
参见https://github.com/graphql-java-kickstart/graphql-spring-boot/issues/32
其他回答
我想为Spring的DurationStyle解析提供支持,在使用Jackson反序列化的自定义配置文件中的属性文件中提供支持,例如将20s序列化为Duration PT20S。我通过在ObjectMapper实例上注册一个自定义反序列化器来实现这一点:
@Bean("customConfigMapper")
public ObjectMapper customConfigMapper() {
final ObjectMapper mapper = new ObjectMapper();
final SimpleModule module = new SimpleModule();
module.addDeserializer(Duration.class, new SpringDurationStyleDeserializer());
mapper.registerModule(module);
return mapper;
}
public static class SpringDurationStyleDeserializer extends JsonDeserializer<Duration> {
@Override
public Duration deserialize(JsonParser jsonParser, DeserializationContext __) throws IOException {
return Optional.ofNullable(jsonParser.getText()).map(DurationStyle::detectAndParse).orElse(null);
}
}
如果你正在使用Spring引导,并且在OffsetDateTime上有这个问题,那么需要使用上面@greperror回答的registerModules(5月28日16日13:04回答),但注意有一个区别。不需要添加提到的依赖项,因为我猜spring boot已经有它了。我有这个问题与春季启动,它为我工作,没有添加这个依赖。
在Jackson JSR的新版本中,例如,registerModule(new JSR310Module())已弃用,现在建议使用JavaTimeModule
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import com.fasterxml.jackson.databind.ObjectMapper;
public class JacksonFactory {
private static ObjectMapper objectMapper = null;
public static ObjectMapper getObjectMapper() {
if (objectMapper == null) {
objectMapper = new ObjectMapper();
objectMapper.registerModule(new JavaTimeModule());
}
return objectMapper;
}
}
如果您因为GraphQL Java工具而遇到此问题,并试图从日期字符串编组Java Instant,则需要设置SchemaParser以使用具有特定配置的ObjectMapper:
在GraphQLSchemaBuilder类中,注入ObjectMapper并添加以下模块:
ObjectMapper objectMapper =
new ObjectMapper().registerModule(new JavaTimeModule())
.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
并将其添加到选项中:
final SchemaParserOptions options = SchemaParserOptions.newOptions()
.objectMapperProvider(fieldDefinition -> objectMapper)
.typeDefinitionFactory(new YourTypeDefinitionFactory())
.build();
参见https://github.com/graphql-java-kickstart/graphql-spring-boot/issues/32
更新:由于历史原因,留下这个答案,但我不建议这样做。请参阅上面接受的答案。
告诉Jackson使用自定义的[反]序列化类进行映射:
@JsonSerialize(using = LocalDateTimeSerializer.class)
@JsonDeserialize(using = LocalDateTimeDeserializer.class)
private LocalDateTime ignoreUntil;
提供自定义类:
public class LocalDateTimeSerializer extends JsonSerializer<LocalDateTime> {
@Override
public void serialize(LocalDateTime arg0, JsonGenerator arg1, SerializerProvider arg2) throws IOException {
arg1.writeString(arg0.toString());
}
}
public class LocalDateTimeDeserializer extends JsonDeserializer<LocalDateTime> {
@Override
public LocalDateTime deserialize(JsonParser arg0, DeserializationContext arg1) throws IOException {
return LocalDateTime.parse(arg0.getText());
}
}
随机事实:如果我在类上面嵌套并且不使它们静态,错误消息是奇怪的: httpmediatypenotsupportedexception:内容类型'application/json;charset=UTF-8'不支持