对于JodaTime的JSON处理Jackson

最新推荐文章于 2022-04-02 14:06:54 发布

原创最新推荐文章于 2022-04-02 14:06:54 发布 · 382 阅读

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本文介绍了如何使用Jackson库自定义序列化器和反序列化器来实现本地时间日期时间的RESTful JSON表示，包括定制日期时间格式输出，并通过实例代码演示了具体实现过程。

正常情况下的JSON 处理，对于JodaTime:

类：

public class ExampleDto {
      private LocalDateTime asDefault = LocalDateTime.now();
      ...

json转换：

import com.fasterxml.jackson.databind.ObjectMapper;
...
ObjectMapper mapper = new ObjectMapper(); 
String json = mapper.writeValueAsString(new ExampleDto());

得到的结果：

{"asDefault":{"era":1,"dayOfMonth":24,"dayOfWeek":6,"dayOfYear":24,"year":2015,"yearOfEra":2015,...}

可以发现的是，不是很RESTFUL，不能很好的处理

Jackson 提供的一种方式，@LocalDateTimeSerializer和@LocalDateTimeDeserializer

public class ExampleDto {
       @JsonSerialize(using = LocalDateTimeSerializer.class)
       @JsonDeserialize(using = LocalDateTimeDeserializer.class)
       private LocalDateTime asArray = LocalDateTime.now();

这样得到的结果是：

{"asArray":[2015,1,24,10,31,3,379]}

从这里看出，我可以定制自己的Serializer，比如我想要得到：

{"custom":
     {"date":"2015-01-24",
      "time":"10:31:03"
}

代码：

Class CustomLocalDateTimeSerializer

public class CustomLocalDateTimeSerializer extends StdScalarSerializer<LocalDateTime> {

      private final static DateTimeFormatter DATE_FORMAT = DateTimeFormat.forPattern("yyyy-MM-dd");
      private final static DateTimeFormatter TIME_FORMAT = DateTimeFormat.forPattern("HH:mm:ss");
 
      public CustomLocalDateTimeSerializer() {
            super(LocalDateTime.class);
      }

      protected CustomLocalDateTimeSerializer(Class<LocalDateTime> t) {
            super(t);
      }

      @Override
      public void serialize(LocalDateTime value, JsonGenerator jgen, SerializerProvider prov      ider) throws IOException, JsonProcessingException {
            jgen.writeStartObject();
            jgen.writeStringField("date", DATE_FORMAT.print(value));
            jgen.writeStringField("time", TIME_FORMAT.print(value));
            jgen.writeEndObject();
      }
}
Class CustomLocalDateTimeDeserializer

public class CustomLocalDateTimeDeserializer extends StdScalarDeserializer<LocalDateTime> {
      private final static DateTimeFormatter DATETIME_FORMAT = DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss");

      public CustomLocalDateTimeDeserializer() {
            super(LocalDateTime.class);
      }

      protected LocalDateTimeDeserializerMongoDb(Class<?> vc) {
            super(vc);
      }

      @Override
      public LocalDateTime deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
           String dateStr = null;
           String timeStr = null;
           String fieldName = null;
           
           while (jp.hasCurrentToken()) {
                JsonToken token = jp.nextToken();
                if (token == JsonToken.FIELD_NAME) {
                     fieldName = jp.getCurrentName();
                } else if (token == JsonToken.VALUE_STRING) {
                     if (StringUtils.equals(fieldName, "date")) {
                          dateStr = jp.getValueAsString();
                     } else if (StringUtils.equals(fieldName, "time")) {
                          timeStr = jp.getValueAsString();
                     } else {
                          throw new JsonParseException("Unexpected field name", jp.getTokenLocation());
                     }
                } else if (token == JsonToken.END_OBJECT) {
                     break;
                }
           }
           if (dateStr != null && timeStr != null) {
                  LocalDateTime dateTime = LocalDateTime.parse(dateStr + " " + timeStr, DATETIME_FORMAT);
                  return dateTime;
            }
         return null;
      }
}