The time difference between international standard time (front desk) and year, month and day is 8 hours. If you use String, the date obtained will be eight hours shorter.

Question: The time difference between international standard time (front desk) and year, month and day is 8 hours. If you use String, the date obtained will be eight hours shorter. 

(Reason: Universal time is standard. Beijing time is 8 hours ahead of universal time)

If the background uses the following to receive the front-end code

//Before modification, you will find that the obtained time is eight hours less than expected 
@TableField(exist = false) 
@ApiModelProperty(value = "Upload date (from), used for query") 
private String syncTimeStart;

should be changed to

//After modification: The time difference between international standard time (front desk) and year, month and day is 8 hours. If you use String, the date obtained will be eight hours less @TableField(exist = 
false) 
@ApiModelProperty(value = "Upload date (starting), Query using ") 
private Date syncTimeStart;

req.setSyncTimeStart(StrUtils.dateTimeChange(req.getSyncTimeStart(),"00:00:00"));
req.setSyncTimeEnd(StrUtils.dateTimeChange(req.getSyncTimeEnd(),"23:59:59"));

 public static Date dateTimeChange (Date date, String time) {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String formatStr = sdf.format(date);
        formatStr = formatStr.substring(0,10)+" "+time;
        Date changeDate = null;
        try {
            changeDate = sdf.parse(formatStr);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return changeDate;
    }

Of course, you can also use two time conversion methods to solve the problem

Time conversion