fastjson在序列化JDK8的LocalDateTime是,无法设置日期格式.

使用的是 1.2.21 这个版本.

不管我设不设置 SerializerFeature.WriteDateUseDateFormat 或者调用JSON.toJSONStringWithDateFormat 都没有其效果. 最后生成的JSON还是 LocalDateTime.toString 的样式.

翻了一下源码. 发现

Jdk8DateCodec#write(JSONSerializer serializer, Object object, Object fieldName, Type fieldType,
                      int features)

这个类. 在直接调用 JSON.toJSONStringWithDateFormat(LocalDateTime.now())的时候,传入的fieldType为null,导致走到 out.writeString(object.toString()); 去了. 从而生成的json为LocalDateTime.toString的格式.

而如果是在一个JAVABean中有LocalDateTime字段,进行序列化的时候. 传入的fieldType是正常的LocalDateTime.class . 但是 if (dateTime.getNano() == 0) 这句过不到,导致还是走到out.writeString(object.toString());中去了.从而生成的json为LocalDateTime.toString的格式.
不大理解 if (dateTime.getNano() == 0) 这句话在这的目的是什么~ 只要我实例化LocalDateTime的时候使用LocalDateTime.now().withNano(0) 就可以格式化时间了. 谢谢!

请提供重现问题的testcase

测试用例:

    @Test
    public void testCase() throws Exception {

        System.out.println("===直接序列化LocalDateTime,无论如何格式不可变化===");
        LocalDateTime dateTime = LocalDateTime.now();
        System.out.println(JSON.toJSONString(dateTime));
        /*期望是 yyyy-MM-dd HH:mm:ss   实际是 LocalDateTime.toString() 的格式 */
        System.out.println(JSON.toJSONString(dateTime,SerializerFeature.WriteDateUseDateFormat));
        System.out.println(JSON.toJSONStringWithDateFormat(dateTime,"yyyy-MM-dd HH:mm:ss"));

        System.out.println("===直接序列化LocalDateTime.withNano(0),无论如何格式不可变化===");
        dateTime = LocalDateTime.now().withNano(0);
        System.out.println(JSON.toJSONString(dateTime));
        /*期望是 yyyy-MM-dd HH:mm:ss   实际是 LocalDateTime.toString() 的格式 */
        System.out.println(JSON.toJSONString(dateTime,SerializerFeature.WriteDateUseDateFormat));
        System.out.println(JSON.toJSONStringWithDateFormat(dateTime,"yyyy-MM-dd HH:mm:ss"));

        System.out.println("==序列化VO对象中包含LocalDateTime,无论如何格式不可变化==");
        LocalDateTimeModel localDateTimeModel = new LocalDateTimeModel();
        System.out.println(JSON.toJSONString(localDateTimeModel));
        /*期望是 yyyy-MM-dd HH:mm:ss   实际是 LocalDateTime.toString() 的格式 */
        System.out.println(JSON.toJSONString(localDateTimeModel,SerializerFeature.WriteDateUseDateFormat));
        System.out.println(JSON.toJSONStringWithDateFormat(localDateTimeModel,"yyyy-MM-dd HH:mm:ss"));

        System.out.println("==序列化VO对象中包含LocalDateTime.withNano(0),日期格式变化正确==");
        localDateTimeModel = new LocalDateTimeModel();
        localDateTimeModel.setStartDateTime(localDateTimeModel.getStartDateTime().withNano(0));
        localDateTimeModel.setEndDateTime(localDateTimeModel.getEndDateTime().withNano(0));
        System.out.println(JSON.toJSONString(localDateTimeModel));
        System.out.println(JSON.toJSONString(localDateTimeModel,SerializerFeature.WriteDateUseDateFormat));
        System.out.println(JSON.toJSONStringWithDateFormat(localDateTimeModel,"yyyy-MM-dd HH:mm:ss"));     
    }

所使用的model:

class LocalDateTimeModel implements Serializable {
    
    private LocalDateTime startDateTime;
    
    private LocalDateTime endDateTime;
    
    private Date startDate;
    
    private Date endDate;

    public LocalDateTimeModel() {
        startDateTime = LocalDateTime.now();
        endDateTime = LocalDateTime.now().plusWeeks(1);

        startDate = new Date();
        endDate = new Date(startDate.getTime()+36000000);
    }

    public LocalDateTime getStartDateTime() {
        return startDateTime;
    }

    public void setStartDateTime(LocalDateTime startDateTime) {
        this.startDateTime = startDateTime;
    }

    public LocalDateTime getEndDateTime() {
        return endDateTime;
    }

    public void setEndDateTime(LocalDateTime endDateTime) {
        this.endDateTime = endDateTime;
    }

    public Date getStartDate() {
        return startDate;
    }

    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }

    public Date getEndDate() {
        return endDate;
    }

    public void setEndDate(Date endDate) {
        this.endDate = endDate;
    }
}

结果:

===直接序列化LocalDateTime,无论如何格式不可变化===
"2016-12-10T11:15:33.308"
"2016-12-10T11:15:33.308"
"2016-12-10T11:15:33.308"
===直接序列化LocalDateTime.withNano(0),无论如何格式不可变化===
"2016-12-10T11:15:33"
"2016-12-10T11:15:33"
"2016-12-10T11:15:33"
==序列化VO对象中包含LocalDateTime,无论如何格式不可变化==
{"endDate":1481375733393,"endDateTime":"2016-12-17T11:15:33.393","startDate":1481339733393,"startDateTime":"2016-12-10T11:15:33.393"}
{"endDate":"2016-12-10 21:15:33","endDateTime":"2016-12-17T11:15:33.393","startDate":"2016-12-10 11:15:33","startDateTime":"2016-12-10T11:15:33.393"}
{"endDate":"2016-12-10 21:15:33","endDateTime":"2016-12-17T11:15:33.393","startDate":"2016-12-10 11:15:33","startDateTime":"2016-12-10T11:15:33.393"}
==序列化VO对象中包含LocalDateTime.withNano(0),日期格式变化正确==
{"endDate":1481375733428,"endDateTime":"2016-12-17 11:15:33","startDate":1481339733428,"startDateTime":"2016-12-10 11:15:33"}
{"endDate":"2016-12-10 21:15:33","endDateTime":"2016-12-17 11:15:33","startDate":"2016-12-10 11:15:33","startDateTime":"2016-12-10 11:15:33"}
{"endDate":"2016-12-10 21:15:33","endDateTime":"2016-12-17 11:15:33","startDate":"2016-12-10 11:15:33","startDateTime":"2016-12-10 11:15:33"}

jdk8 LocalDateTime support dateformat. issue #942

1.2.23中问题已经修复，会尽快发布新版本

jdk8 LocalDateTime support dateformat. issue #942

Fastjson把对象转为json时候，Date会转为时间戳，那LocalDateTime怎么转为时间戳呢

同问，LocalDateTime怎么转为时间戳？

追问,LocalDateTime怎么转换为时间戳呀

jdk8 LocalDateTime support dateformat. issue alibaba#942

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fastjson在序列化JDK8的LocalDateTime是,无法设置日期格式. #942

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