練習：將從表讀出來的時間戳除以1000（java讀時間戳會多出3個000）jackson包 實現

entity

@Entity
@DynamicUpdate  //自動更新日期
@Data //get/set
public class OrderDetail {


    @Id
    private String detailId;

    /**訂單id**/
    private String orderId;

    /**商品id**/
    private String productId;

    /**商品名**/
    private String productName;

    /**商品價格**/
    private BigDecimal productPrice;

    /**購票數量**/
    private Integer productQuantity;

    /**商品圖片**/
    private String productIcon;

    /**時間戳**/
    private Date createTimestamp;

    /**時間戳**/
    private Date updateTimestamp;
}

java讀出的資料格式,時間戳會精確到毫秒，多出3個000

{
  "statusCode": 0,
  "message": "返回成功",
  "data": [{
    "orderId": "1542785381425923730",
    "buyerName": "王五",
    "buyerPhone": "15605852476",
    "buyerAddr": "北京王府井",
    "buyerOpenid": "110112",
    "buyerAmount": 4.40,
    "orderStatus": 0,
    "payStatus": 0,
    "createTimestamp": 1542794276000,
    "updateTimestamp": 1542794276000,
    "orderDetailList": null
  }]
}

解決方法：

1.繼承com.fasterxml.jackson.databind.JsonSerializer;的類，並複寫：serialize(T.....)方法

public class DateToTimestamp extends JsonSerializer<Date> {
    @Override
    public void serialize(Date date, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {
        jsonGenerator.writeNumber(date.getTime() / 1000);
    }
}

2.在實體類上用上新建的 DateToTimestamp 類的註解

@Entity
@DynamicUpdate //自動更新日期
@Data //get/set
public class OrderMaster {

    @Id
    private String orderId;

    /**買家名字**/
    private String buyerName;

    /**買家手機**/
    private String buyerPhone;

    /**買家地址**/
    private String buyerAddr;

    /**使用者openid**/
    private String buyerOpenid;

    /**訂單金額**/
    private BigDecimal buyerAmount;

    /**訂單狀態, 預設狀態0新訂單**/
    private Integer orderStatus = OrderStatusEnum.NEW.getCode();

    /**支付狀態, 預設狀態0等待支付**/
    private Integer payStatus = PayStatusEnum.WAIT.getCode();

    /**
     * 此註解表示時間戳除以1000
     */
    @JsonSerialize(using = DateToTimestamp.class)
    private Date createTimestamp;

    /**
     * 此註解表示時間戳除以1000
     */
   @JsonSerialize(using = DateToTimestamp.class)
    private Date updateTimestamp;

}