title: Regex in spring controller
body: <p>I am trying to build a request filter that will only get used if it matches a pattern of the letter e, then a number.  However I cannot seem to get it to work. I keep getting 400 errors every time I try something with regex.</p>
  
  <p>If I just use the following it "works" but also captures mappings that do not have numbers which I don't want. </p>
  
  <pre><code>@RequestMapping(value = "e{number}",
              method = RequestMethod.GET)
  </code></pre>
  
  <p>I have tried the following combinations.</p>
  
  <pre><code>@RequestMapping(value = "e{number}",
              params = "number:\\d+",
              method = RequestMethod.GET)
  
  @RequestMapping(value = "e{number:\d+}",
              method = RequestMethod.GET)
  
  @RequestMapping(value = "/e{^\\+?\\d+\$}",
              method = RequestMethod.GET)
  
  @RequestMapping(value = "/{^\\e+?\\d+\$}",
              method = RequestMethod.GET)
  </code></pre>