Jackson enum序列化和反序列化

我使用JAVA 1.6和Jackson 1.9.9，我有一个enum

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;
    }
}

我已经添加了一个@JsonValue，这似乎做的工作，它序列化对象:

{"event":"forgot password"}

但当我尝试反序列化时，我得到

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

我错过了什么?

当前回答

我发现最简单的方法是使用@JsonFormat.Shape。枚举的OBJECT注释。

@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum MyEnum{
    ....
}

2019-05-29 12:00:41

其他回答

我喜欢公认的答案。但是，我想稍微改进一下(考虑到现在有高于版本6的Java可用)。

例子:

    public enum Operation {
        EQUAL("eq"),
        NOT_EQUAL("ne"),
        LESS_THAN("lt"),
        GREATER_THAN("gt");

        private final String value;

        Operation(String value) {
            this.value = value;
        }

        @JsonValue
        public String getValue() {
            return value;
        }

        @JsonCreator
        public static Operation forValue(String value) {
            return Arrays.stream(Operation.values())
                .filter(op -> op.getValue().equals(value))
                .findFirst()
                .orElseThrow(); // depending on requirements: can be .orElse(null);
        }
    }

2021-03-23 16:08:34

如果您希望将枚举类与其JSON表示完全解耦，@xbakesx指出的序列化器/反序列化器解决方案是一个很好的解决方案。

或者，如果您更喜欢自包含的解决方案，那么基于@JsonCreator和@JsonValue注释的实现将更方便。

因此，利用@Stanley的例子，下面是一个完整的自包含解决方案(Java 6, Jackson 1.9):

public enum DeviceScheduleFormat {

    Weekday,
    EvenOdd,
    Interval;

    private static Map<String, DeviceScheduleFormat> namesMap = new HashMap<String, DeviceScheduleFormat>(3);

    static {
        namesMap.put("weekday", Weekday);
        namesMap.put("even-odd", EvenOdd);
        namesMap.put("interval", Interval);
    }

    @JsonCreator
    public static DeviceScheduleFormat forValue(String value) {
        return namesMap.get(StringUtils.lowerCase(value));
    }

    @JsonValue
    public String toValue() {
        for (Entry<String, DeviceScheduleFormat> entry : namesMap.entrySet()) {
            if (entry.getValue() == this)
                return entry.getKey();
        }

        return null; // or fail
    }
}

2013-12-06 10:23:35

@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum LoginOptionType {

 PHONE(1, "Phone"), MAIL(2, "mail"), PERSONAL_EMAIL(3, "Personal email");

private static List<LoginOptionType> all;

static {
    all = new ArrayList<LoginOptionType>() {
        {
            add(LoginOptionType.PHONE);
            add(LoginOptionType.MAIL);
            add(LoginOptionType.PERSONAL_EMAIL);
        }
    };
}

private final Integer viewValue;

private final String name;

LoginOptionType(Integer viewValue, String name) {
    this.viewValue = viewValue;
    this.name = name;
}

public Integer getViewValue() {
    return viewValue;
}

public String getName() {
    return name;
}

public static List<LoginOptionType> getAll() {
    return all;
}
}

响应

[
{
    "viewValue": 1,
    "name": "Phone"
},
{
    "viewValue": 2,
    "name": "mail"
},
{
    "viewValue": 3,
    "name": "Personal email"
}
]

2021-12-01 05:44:33

我是这样做的:

// Your JSON
{"event":"forgot password"}

// Your class to map 
public class LoggingDto {
    @JsonProperty(value = "event")
    private FooEnum logType;
}

//Your enum
public enum FooEnum {

    DATA_LOG ("Dummy 1"),
    DATA2_LOG ("Dummy 2"),
    DATA3_LOG ("forgot password"),
    DATA4_LOG ("Dummy 4"),
    DATA5_LOG ("Dummy 5"),
    UNKNOWN ("");

    private String fullName;

    FooEnum(String fullName) {
        this.fullName = fullName;
    }

    public String getFullName() {
        return fullName;
    }

    @JsonCreator
    public static FooEnum getLogTypeFromFullName(String fullName) {
        for (FooEnum logType : FooEnum.values()) {
            if (logType.fullName.equals(fullName)) {
                return logType;
            }
        }
        return UNKNOWN;
    }


}

因此，类LoggingDto的属性“logType”的值将是DATA3_LOG

2020-07-02 09:55:15

可以采用多种方法将JSON对象反序列化为枚举。我最喜欢的风格是创建一个内部类:

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonProperty;
import org.hibernate.validator.constraints.NotEmpty;

import java.util.Arrays;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;

import static com.fasterxml.jackson.annotation.JsonFormat.Shape.OBJECT;

@JsonFormat(shape = OBJECT)
public enum FinancialAccountSubAccountType {
  MAIN("Main"),
  MAIN_DISCOUNT("Main Discount");

  private final static Map<String, FinancialAccountSubAccountType> ENUM_NAME_MAP;
  static {
    ENUM_NAME_MAP = Arrays.stream(FinancialAccountSubAccountType.values())
      .collect(Collectors.toMap(
        Enum::name,
        Function.identity()));
  }

  private final String displayName;

  FinancialAccountSubAccountType(String displayName) {
    this.displayName = displayName;
  }

  @JsonCreator
  public static FinancialAccountSubAccountType fromJson(Request request) {
    return ENUM_NAME_MAP.get(request.getCode());
  }

  @JsonProperty("name")
  public String getDisplayName() {
    return displayName;
  }

  private static class Request {
    @NotEmpty(message = "Financial account sub-account type code is required")
    private final String code;
    private final String displayName;

    @JsonCreator
    private Request(@JsonProperty("code") String code,
                    @JsonProperty("name") String displayName) {
      this.code = code;
      this.displayName = displayName;
    }

    public String getCode() {
      return code;
    }

    @JsonProperty("name")
    public String getDisplayName() {
      return displayName;
    }
  }
}

2016-08-31 22:05:55

Jackson enum序列化和反序列化

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