相关疑难解决方法(0)

我正在使用JAVA 1.6和Jackson 1.9.9我有一个枚举

public enum Event {
    FORGOT_PASSWORD("forgot password");

    private final String value;

    private Event(final String description) {
        this.value = description;
    }

    @JsonValue
    final String value() {
        return this.value;
    }
}

我添加了一个@JsonValue,这似乎完成了将对象序列化为:

{"event":"forgot password"}

但是当我尝试反序列化时,我得到了一个

Caused by: org.codehaus.jackson.map.JsonMappingException: Can not construct instance of com.globalrelay.gas.appsjson.authportal.Event from String value 'forgot password': value not one of declared Enum instance names

我在这里错过了什么？

我正在尝试并且没有用Jackson 2.5.4反序列化枚举,我在那里看不到我的情况.我的输入字符串是驼峰式的,我想简单地映射到标准的Enum约定.

@JsonFormat(shape = JsonFormat.Shape.STRING)
public enum Status {
    READY("ready"),
    NOT_READY("notReady"),
    NOT_READY_AT_ALL("notReadyAtAll");

    private static Map<String, Status> FORMAT_MAP = Stream
            .of(Status.values())
            .collect(toMap(s -> s.formatted, Function.<Status>identity()));

    private final String formatted;

    Status(String formatted) {
        this.formatted = formatted;
    }

    @JsonCreator
    public Status fromString(String string) {
        Status status = FORMAT_MAP.get(string);
        if (status == null) {
            throw new IllegalArgumentException(string + " has no corresponding value");
        }
        return status;
    }
}

我也尝试过@JsonValue一个无用的吸气剂,这是我在别处看到的一个选项.他们都爆炸了:

com.fasterxml.jackson.databind.exc.InvalidFormatException: Can not construct instance of ...Status from String value 'ready': value not …

我有一个JSON对象,如:

{"name":"John", "grade":"A"}

要么

{"name":"Mike", "grade":"B"}

要么

{"name":"Simon", "grade":"C"}

等等

我试图将上面的JSON映射到:

@JsonIgnoreProperties(ignoreUnknown = true)
public class Employee{
      @JsonIgnoreProperties(ignoreUnknown = true)
      public enum Grade{ A, B, C }
      Grade grade;
      String name;

  public Grade getGrade() {
    return grade;
  }

  public void setGrade(Grade grade) {
    this.grade = grade;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }
}

上面的映射工作正常,但将来会有更多的"等级"类型,比如D,E等打破现有的映射并抛出以下异常

05-08 09:56:28.130: W/System.err(21309): org.codehaus.jackson.map.JsonMappingException: Can not construct instance of Employee from String value 'D': value …

我试图使用Jackson将JSON反序列化为Java POJO.在不泄露机密信息的情况下,这是ObjectMapper反序列化失败时的示例堆栈跟踪:

org.codehaus.jackson.map.JsonMappingException: Can not construct Map key of type com.example.MyEnum from String "coins": not a valid representation: Can not construct Map key of type com.example.MyEnum from String "coins": not one of values for Enum class

我的JSON看起来像这样:

"foo": {
    "coins": null,
    ...
}

我要反序列化的类有这个字段:

private Map<MyEnum, MyPojo> foo;

我的枚举类型看起来像这样:

public enum MyEnum {
    COINS("coins"),
    ...
}

我确实意识到我正在尝试反序列化null值.但我相信这仍然有效:反序列化的结果应该等同于使用Map foo.put(MyEnum.COINS, null),这确实是一个有效的Java指令.非常感谢帮助,在此先感谢.