public enum ClusterType {
TEMPERATURE("0402"),
HUMIDITY("0405"),
ENERGY_DETAILS("0702"),
SMART_SOCKET_STATUS("0006"),
ALARMED("0500");
private String value = null;
ClusterType(String byteStr) {
this.value = byteStr;
}
@JsonCreator
public static ClusterType fromValue(final String val){
return (ClusterType) CollectionUtils.find(Arrays.asList(ClusterType.values()), new Predicate() {
public boolean evaluate(Object object) {
ClusterType candidate = (ClusterType) object;
return StringUtils.equals(candidate.value, val);
}
});
}
@JsonValue
public String getValue(){
return value;
}
public byte[] get() {
return ByteUtils.hexStringToByteArray(value);
}
public boolean equals(String cluster) {
return StringUtils.equals(cluster, value);
}
}
我有以上列举
@JsonValue
公共字符串getValue(){
返回值
}
部分和示例测试类,例如...
公共课Foo {
public static void main(String[] args) {
try {
ObjectMapper objectMapper = new ObjectMapper();
ClusterType []arrayRep = new ClusterType[]{ClusterType.ALARMED, ClusterType.TEMPERATURE};
Map<String, ClusterType> mapRepAsValue = new HashMap<>();
mapRepAsValue.put("1", ClusterType.ALARMED);
mapRepAsValue.put("2", ClusterType.TEMPERATURE);
Map<ClusterType, String> mapRepAsKey = new HashMap<>();
mapRepAsKey.put(ClusterType.ALARMED, "1");
mapRepAsKey.put(ClusterType.TEMPERATURE, "2");
System.out.println(objectMapper.writeValueAsString(arrayRep));
System.out.println(objectMapper.writeValueAsString(mapRepAsValue));
System.out.println(objectMapper.writeValueAsString(mapRepAsKey));
} catch (JsonProcessingException e) {
e.printStackTrace();
}
} }
该测试类打印出来
["0500","0402"]
{"2":"0402","1":"0500"}
{"TEMPERATURE":"2","ALARMED":"1"}
在作为映射键的枚举字段上使用时,@ JsonValue不起作用。
序列化地图时,有没有办法将此枚举用作键?
谢谢。
最佳答案
Jackson使用MapSerializer
序列化Map
类型,并使用StdKeySerializer
序列化密钥。它实现为
@Override
public void serialize(Object value, JsonGenerator jgen, SerializerProvider provider)
throws IOException, JsonGenerationException
{
if (value instanceof Date) {
provider.defaultSerializeDateKey((Date) value, jgen);
} else {
jgen.writeFieldName(value.toString());
}
}
您可以看到它只是获取对象的
toString()
值。因此,您可以像这样在toString()
中覆盖enum
方法public String toString() {
return getValue();
}
@JsonValue
变得无用。另外,如果您需要
toString()
保持相同(或默认),则可以创建一个自定义类型来包装Map
class CustomType {
private Map<ClusterType, String> map;
@JsonAnyGetter // necessary to unwrap the Map to the root object, see here: http://jira.codehaus.org/browse/JACKSON-765
@JsonSerialize(keyUsing = ClusterTypeKeySerializer.class)
public Map<ClusterType, String> getMap() {
return map;
}
public void setMap(Map<ClusterType, String> map) {
this.map = map;
}
}
并使用自定义的
JsonSerializer
class ClusterTypeKeySerializer extends StdSerializer<ClusterType> {
protected ClusterTypeKeySerializer() {
super(ClusterType.class);
}
@Override
public void serialize(ClusterType value, JsonGenerator jgen,
SerializerProvider provider) throws IOException,
JsonGenerationException {
jgen.writeFieldName(value.getValue());
}
}
使用
ClusterType#getValue()
方法。同样,我们不使用@JsonValue
。