我有一个Enum描述如下：
public enum OrderType {
UNKNOWN(0, "Undefined"),
TYPEA(1, "Type A"),
TYPEB(2, "Type B"),
TYPEC(3, "Type C");
private Integer id;
private String name;
private WorkOrderType(Integer id, String name) {
this.id = id;
this.name = name;
}
//Setters, getters....
}
我使用我的控制器（new OrderType[] {UNKNOWN,TYPEA,TYPEB,TYPEC};）返回枚举数组，然后Spring将其序列化为以下json字符串：
["UNKNOWN", "TYPEA", "TYPEB", "TYPEC"]
迫使杰克逊像POJO一样序列化枚举的最佳方法是什么？例如。：
[
{"id": 1, "name": "Undefined"},
{"id": 2, "name": "Type A"},
{"id": 3, "name": "Type B"},
{"id": 4, "name": "Type C"}
]
我玩了不同的注释但无法获得这样的结果。
最后我自己找到了解决方案
我不得不用@JsonSerialize(using = OrderTypeSerializer.class)注释enum并实现自定义序列化器：
public class OrderTypeSerializer extends JsonSerializer<OrderType> {
@Override
public void serialize(OrderType value, JsonGenerator generator,
SerializerProvider provider) throws IOException,
JsonProcessingException {
generator.writeStartObject();
generator.writeFieldName("id");
generator.writeNumber(value.getId());
generator.writeFieldName("name");
generator.writeString(value.getName());
generator.writeEndObject();
}
}
@JsonFormat(shape= JsonFormat.Shape.OBJECT)
public enum SomeEnum
从https://github.com/FasterXML/jackson-databind/issues/24开始
刚测试它适用于版本2.1.2
回答TheZuck：
我试过你的例子，得到了Json：
{"events":[{"type":"ADMIN"}]}
我的代码：
@RequestMapping(value = "/getEvent") @ResponseBody
public EventContainer getEvent() {
EventContainer cont = new EventContainer();
cont.setEvents(Event.values());
return cont;
}
class EventContainer implements Serializable {
private Event[] events;
public Event[] getEvents() {
return events;
}
public void setEvents(Event[] events) {
this.events = events;
}
}
和依赖是：
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>${jackson.version}</version>
<exclusions>
<exclusion>
<artifactId>jackson-annotations</artifactId>
<groupId>com.fasterxml.jackson.core</groupId>
</exclusion>
<exclusion>
<artifactId>jackson-core</artifactId>
<groupId>com.fasterxml.jackson.core</groupId>
</exclusion>
</exclusions>
</dependency>
<jackson.version>2.1.2</jackson.version>
我找到了一个非常简洁的解决方案，当你不能像我的情况那样修改枚举类时特别有用。然后，您应该提供自定义的ObjectMapper，并启用某个功能。自Jackson 1.6以来，这些功能可用。
public class CustomObjectMapper extends ObjectMapper {
@PostConstruct
public void customConfiguration() {
// Uses Enum.toString() for serialization of an Enum
this.enable(WRITE_ENUMS_USING_TO_STRING);
// Uses Enum.toString() for deserialization of an Enum
this.enable(READ_ENUMS_USING_TO_STRING);
}
}
有更多与枚举相关的功能，请参见此处：
https://github.com/FasterXML/jackson-databind/wiki/Serialization-features https://github.com/FasterXML/jackson-databind/wiki/Deserialization-Features
这是我的解决方案。我想将变换枚举变为{id: ..., name: ...}形式。
随着杰克逊1.x：
pom.hml：
<properties>
<jackson.version>1.9.13</jackson.version>
</properties>
<dependencies>
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-core-asl</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-mapper-asl</artifactId>
<version>${jackson.version}</version>
</dependency>
</dependencies>
rule.Java:
import org.codehaus.jackson.map.annotate.JsonSerialize;
import my.NamedEnumJsonSerializer;
import my.NamedEnum;
@Entity
@Table(name = "RULE")
public class Rule {
@Column(name = "STATUS", nullable = false, updatable = true)
@Enumerated(EnumType.STRING)
@JsonSerialize(using = NamedEnumJsonSerializer.class)
private Status status;
public Status getStatus() { return status; }
public void setStatus(Status status) { this.status = status; }
public static enum Status implements NamedEnum {
OPEN("open rule"),
CLOSED("closed rule"),
WORKING("rule in work");
private String name;
Status(String name) { this.name = name; }
public String getName() { return this.name; }
};
}
named enum.Java:
package my;
public interface NamedEnum {
String name();
String getName();
}
named enum JSON serialize R.Java:
package my;
import my.NamedEnum;
import java.io.IOException;
import java.util.*;
import org.codehaus.jackson.JsonGenerator;
import org.codehaus.jackson.JsonProcessingException;
import org.codehaus.jackson.map.JsonSerializer;
import org.codehaus.jackson.map.SerializerProvider;
public class NamedEnumJsonSerializer extends JsonSerializer<NamedEnum> {
@Override
public void serialize(NamedEnum value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException {
Map<String, String> map = new HashMap<>();
map.put("id", value.name());
map.put("name", value.getName());
jgen.writeObject(map);
}
}
随着杰克逊2.x：
pom.hml：
<properties>
<jackson.version>2.3.3</jackson.version>
</properties>
<dependencies>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>${jackson.version}</version>
</dependency>
</dependencies>
rule.Java:
import com.fasterxml.jackson.annotation.JsonFormat;
@Entity
@Table(name = "RULE")
public class Rule {
@Column(name = "STATUS", nullable = false, updatable = true)
@Enumerated(EnumType.STRING)
private Status status;
public Status getStatus() { return status; }
public void setStatus(Status status) { this.status = status; }
@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public static enum Status {
OPEN("open rule"),
CLOSED("closed rule"),
WORKING("rule in work");
private String name;
Status(String name) { this.name = name; }
public String getName() { return this.name; }
public String getId() { return this.name(); }
};
}
Rule.Status.CLOSED翻译成{id: "CLOSED", name: "closed rule"}。
序列化Enum的一种简单方法是使用@JsonFormat注释。 @JsonFormat可以通过三种方式配置Enum的序列化。
@JsonFormat.Shape.STRING
public Enum OrderType {...}
使用OrderType :: name作为序列化方法。 OrderType.TypeA的序列化是“TYPEA”
@JsonFormat.Shape.NUMBER
Public Enum OrderTYpe{...}
使用OrderType :: ordinal作为序列化方法。 OrderType.TypeA的序列化是1
@JsonFormat.Shape.OBJECT
Public Enum OrderType{...}
将OrderType视为POJO。 OrderType.TypeA的序列化是{"id":1,"name":"Type A"}
JsonFormat.Shape.OBJECT就是您所需要的。
一个更复杂的方法是你的解决方案，为Enum指定一个序列化器。
使用@JsonCreator注释，创建方法getType（），使用toString或对象工作进行序列化
{"ATIVO"}
要么
{"type": "ATIVO", "descricao": "Ativo"}
...
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.JsonNodeType;
@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum SituacaoUsuario {
ATIVO("Ativo"),
PENDENTE_VALIDACAO("Pendente de Validação"),
INATIVO("Inativo"),
BLOQUEADO("Bloqueado"),
/**
* Usuarios cadastrados pelos clientes que não possuem acesso a aplicacao,
* caso venham a se cadastrar este status deve ser alterado
*/
NAO_REGISTRADO("Não Registrado");
private SituacaoUsuario(String descricao) {
this.descricao = descricao;
}
private String descricao;
public String getDescricao() {
return descricao;
}
// TODO - Adicionar metodos dinamicamente
public String getType() {
return this.toString();
}
public String getPropertieKey() {
StringBuilder sb = new StringBuilder("enum.");
sb.append(this.getClass().getName()).append(".");
sb.append(toString());
return sb.toString().toLowerCase();
}
@JsonCreator
public static SituacaoUsuario fromObject(JsonNode node) {
String type = null;
if (node.getNodeType().equals(JsonNodeType.STRING)) {
type = node.asText();
} else {
if (!node.has("type")) {
throw new IllegalArgumentException();
}
type = node.get("type").asText();
}
return valueOf(type);
}
}