HttpServer Request 从查询字符串中获取日期范围

Question

I am new to Java and Vertx and I have a query string with the following format:

GET /examples/1/data?date_1[gt]=2021-09-28&date_1[lt]=2021-10-28

Here I have this date_1 parameter which is within a certain range. I have been using HttpServerRequest class to extract simple parameters like integers but not sure how to proceed with these kind of range parameters.

With the simple parameters, I can do something like:

String param = request.getParam(paramName);
paramAsInteger = Integer.valueOf(paramAsString);

However, confused as to how to deal with the gt and lt options and the fact that we have same parameter twice.

Answer 1

You say that you have difficulties parsing out these tokens. Here's how you can handle this.

1. The first thing to understand is that the parameter name is NOT "date1"

2. There are actually two parameters here 2.1. "date_1[gt]" with a value of "2021-09-28" 2.2. "date_1[lt]" with a value of "2021-10-28"

3. This is because in the URI parameter definition everything before the "=" sign is the parameter name and everything after is the parameter value.

4. You can just do

String dateAsString = request.getParam("date1[gt]");
paramAsInteger = toDate(dateAsString)

5. To implement the toDate() function read this simple article how to convert a string object into a data object using a standard library ( link )

Answer 2

Vert.x will treat these parameters as two separate ones. So RoutingContext#queryParam("date_1[gt]") will only give you the value for [gt] . If you want the value for [lt] you need to get that separately.

That being said, you can move this tedious logic into an extra handler and store the values in the RoutingContext . Something like this might be easier:

private void extractDates(RoutingContext ctx) {
    var startDate = ctx.queryParam("date_1[gt]");
    var endDate = ctx.queryParam("date_1[lt]");

    var parsedStartDate = DateTimeFormatter.ISO_LOCAL_DATE.parse(startDate.get(0));
    var parsedEndDate = DateTimeFormatter.ISO_LOCAL_DATE.parse(endDate.get(0));

    // things we put in the context here can be retrieved by later handlers
    ctx.put("startDate", parsedStartDate);
    ctx.put("endDate", parsedEndDate);

    ctx.next();
}

Then, in your actual handler you can access the two dates as follows:

router.get("/date")
        .handler(this::extractDates)
        .handler(ctx -> {
            var responseBody = ctx.get("startDate") + " - " + ctx.get("endDate");
            ctx.end(responseBody);
        });

This allows you to keep your actual business logic concise.