How to replace a placeholder in a String with a SimpleDateFormat Pattern

Question

In a given String like this

".../uploads/${customer}/${dateTime('yyyyMMdd')}/report.pdf"

I need to replace a customer and a yyyyMMdd timestamp.

To replace the customer placeholder, I could use the StrSubstitutor from Apache Commons. But how to replace the SimpleDateFormat? We are running in a Spring enviourment, so maybe Spring EL is an option?

The markup for the placeholders is not fixed, it is ok if another library needs syntactical changes.

This small tests shows the problem:

SimpleDateFormat            formatter   = new SimpleDateFormat("yyyyMMdd");

String                      template    = ".../uploads/${customer}/${dateTime('yyyyMMdd')}/report.pdf";

@Test
public void shouldResolvePlaceholder()
{
    final Map<String, String> model = new HashMap<String, String>();
    model.put("customer", "Mr. Foobar");

    final String filledTemplate = StrSubstitutor.replace(this.template, model);

    assertEquals(".../uploads/Mr. Foobar/" + this.formatter.format(new Date()) + "/report.pdf", filledTemplate);
}

Answer 1

Why don't you use MessageFormat instead?

String result = MessageFormat.format(".../uploads/{0}/{1,date,yyyyMMdd}/report.pdf", customer, date);

Or with String.format

String result = String.format(".../uploads/%1$s/%2$tY%2$tm%2$td/report.pdf", customer, date);