无法读取 JSON

Question

我的控制器如下所示。 RelationType 是 Table class 中的字段。我得到以下异常。有什么想法吗？

org.springframework.http.converter.HttpMessageNotReadableException: Could not read JSON: Can not construct instance of com.mycompany.myapp.core.domain.RelationType from String value 'unionetomany': value not one of declared Enum instance names: [unionetoone, unionetomany]
 at [Source: org.apache.catalina.connector.CoyoteInputStream@7b3e44cb; line: 1, column: 435] (through reference chain: com.mycompany.myapp.core.domain.Table["relations"]->com.mycompany.myapp.core.domain.Relation["relationtype"]); nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: Can not construct instance of com.mycompany.myapp.core.domain.RelationType from String value 'unionetomany': value not one of declared Enum instance names: [unionetoone, unionetomany, unimanytoone, unimanytomany, bionetoone, bionetomany, bimanytoone, bimanytomany]
 at [Source: org.apache.catalina.connector.CoyoteInputStream@7b3e44cb; line: 1, column: 435] (through reference chain: com.mycompany.myapp.core.domain.Table["relations"]->com.mycompany.myapp.core.domain.Relation["relationtype"])
    at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.readJavaType(MappingJackson2HttpMessageConverter.java:228)
    at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.read(MappingJackson2HttpMessageConverter.java:220)
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:138)
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.readWithMessageConverters(RequestResponseBodyMethodProcessor.java:183)
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:98)
    at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:79)

@RequestMapping(method = RequestMethod.POST)
    public void validateSchema(@RequestBody Table[] tables, HttpServletRequest request) {
    ......
}

public enum RelationType {
  UNI_ONE_TO_ONE("unionetoone"),
  UNI_ONE_TO_MANY("unionetomany");

  private final String text;

  private RelationType(final String text) {
      this.text = text;
  }

  @Override
  public String toString() {
      return text;
  }
}

Answer 1

默认情况下Enums name用于序列化，而不是toString() returns。因此，虽然错误消息令人困惑（它应该列出预期的实际值），但问题是它预期 UNI_ONE_TO_MANY.

如果你想使用toString()返回的值，你应该可以在toString()方法中添加注释@JsonValue，这应该表明该值应该用于序列化.

另一种方法是启用 DeserializationFeature.READ_ENUMS_USING_TO_STRING，这将在全局范围内更改行为。

无法读取 JSON

Could not read JSON

spring

json

spring-mvc

jackson