java - JsonMappingException : Unexpected token (START_OBJECT)

Question

我对 Codehaus Jackson 的用户有疑问。我有一个具有下一个属性和映射器声明的对象:

public class AuthenticatedPrincipal implements Serializable, Principal {
      @JsonIgnore
      private final static ObjectMapper mapper = new ObjectMapper().enable(DeserializationConfig.Feature.ACCEPT_SINGLE_VALUE_AS_ARRAY).enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL)
      .setSerializationInclusion(JsonSerialize.Inclusion.NON_NULL).setVisibility(JsonMethod.FIELD, JsonAutoDetect.Visibility.ANY);

  private String name;

  private Collection<String> roles;

  private Collection<String> groups;

  private boolean adminPrincipal;
...
  @JsonIgnore
  public String serialize() {
    try {
      return mapper.writeValueAsString(this);
    } catch (IOException e) {
      throw new RuntimeException("Unable to serialize Principal:" + toString(), e);
    }
  }

  @JsonIgnore
  public static AuthenticatedPrincipal deserialize(String json) {
    try {
      return mapper.readValue(json, AuthenticatedPrincipal.class);
    } catch (IOException e) {
      throw new RuntimeException("Unable to serialize Principal:" + json, e);
    }
  }
}

这是从另一个类中使用的:

public class AuthRequest {

  @Transient
  private AuthenticatedPrincipal principal;
  @PreUpdate
  @PrePersist
  public void encodePrincipal() {
    if (principal != null) {
        this.encodedPrincipal = principal.serialize();
    }
  }

  @PostLoad
  @PostPersist
  @PostUpdate
  public void decodePrincipal() {
    if (StringUtils.isNotBlank(encodedPrincipal)) {
        this.principal = AuthenticatedPrincipal.deserialize(encodedPrincipal);
    }
  }
}

当我执行生成这样一个字符串的功能时:

Principal:{"adminPrincipal":false,"displayName":"sdfas","groupAware":false,"name":"sdfas"}

当方法AuthenticatedPrincipal.deserialize(encodedPrincipal);被称为解析 Json 参数，但该方法失败并出现此错误:

org.codehaus.jackson.map.JsonMappingException: Unexpected token (START_OBJECT), expected START_ARRAY: need JSON Array to contain As.WRAPPER_ARRAY type information for class com.trent.app.lib.principal.AuthenticatedPrincipal
 at [Source: java.io.StringReader@40fa255; line: 1, column: 1]

谁能帮帮我？

Answer 1

Principal:{"adminPrincipal":false,"displayName":"sdfas","groupAware":false,"name":"sdfas"}

不是有效的 JSON。它需要看起来像这样

{"adminPrincipal":false,"displayName":"sdfas","groupAware":false,"name":"sdfas"}

(没有 Principal: 开头)