Report 400: data type mismatch:

The type of time passed in the path URL is string

You can add this annotation in the controller layer to convert string to java.util.date

@DateTimeFormat(pattern = "yyyy-MM-dd") Date begin

 @GetMapping
    public List<Demand> listAll(@RequestParam("begin") @DateTimeFormat(pattern = "yyyy-MM-dd") Date beginTime, @RequestParam("end") @DateTimeFormat(pattern = "yyyy-MM-dd")Date endTime){
        System.out.println("beginTime"+beginTime);
        System.out.println("endTime:"+endTime);
        return demandClient.queryAllDemands(beginTime, endTime);
    }

date begintime in the figure; If the front-end parameter is not begintime but begin, it needs to be defined as begin. in @ requestparam