How do you handle errors in your resources?

Question

Java

Here is a typical resource code (JAR-RS) in a project:

@Path("authenticate")
@POST
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Response authenticate(Credentials credentials) {
  try{
     // some logic
  } catch (Exception1 e) { 
            //   etc  LOGGER.error(e);
            //   return Response.status(Status.UN_AUTHORIZED).build();
   } catch (Exception2 e) { 
            //   etc  LOGGER.error(e);
            //   return Response.status(Status.CAN_NOT_CREATE_TOKEN).build();
   }  catch (Exception3 e) { 
         //   etc  LOGGER.error(e);
         //   return Response.status(Status.SOME_OTHER_ERROR).build();
   }

  
  // return good stuff
}

The code is working, but not beautiful. I googled how to reduce the number of catch without damage - I didn’t find it, I rummaged through the rest book, I didn’t find it either. Anyone who has experienced this before can share their experience? I want to reduce the number of catches without harm, because in some places there are 10 catches.
More or less useful find

Answer 1

1. Catch an error if you can handle it. Otherwise, throw it out of the method
2. In java 7 catch you can combine catch(NullPointerException | ClassNotFindException)
3. Take the base class of the error to catch all catch(Exception)
This amount of catch is normal, especially when working with http.

Answer 2

If you use Jersey, then you can like this https://jersey.java.net/documentation/latest/repre...
If not, I advise you to try :)

Answer 3

In this particular case, I would make some kind of auxiliary class that returns the desired status depending on the error class.
for example

public static Status getStatus(Exception e) {
        if (e.getClass.equals(MyCoolUnautorisedException.class)) {
           return Status.UN_AUTHORIZED;
        }
        // More Exception handlers
     return null; //If something gone wrong
     }
  //Main code
    try {
       // some logic
    } catch (Exception e) { 
              //   etc  LOGGER.error(e);
              return Response.status(SomeStatusHandler.getStatus(e)).build();
    } finally {
        //Here we go!
    }

Answer 4

Another "exotic" option, you can make an
Exception => Status map
, or more generic, like Exception => Handler
and collapse all the catches into a simple map call. Something like this.
With a map it is convenient if you have a lot of typical handlers.

Answer 5

Most rest frameworks provide the ability to write custom ExceptionMappers.

Answer 6

Swift 4 Xcode 9.0

import Foundation

// Дополним String для простоты работы с NSRegularExpression
extension String {
    // Вычислимое св-во, которое возвращает NSRange строки String
    var toNSRange: NSRange { return NSMakeRange(0, self.utf16.count) }

    // Метод возвращающий String по заданному NSRange
    func substringFromNSRange(with nsrange: NSRange) -> String? {
        guard let range = Range(nsrange) else { return nil }
        let start = String.UTF16Index(encodedOffset: range.lowerBound)
        let end = String.UTF16Index(encodedOffset: range.upperBound)
        return String(self.utf16[start..<end])
    }
}

var htmlContext = "products_and_categories(123123)]}"
let regExp = try? NSRegularExpression(pattern: "products_and_categories(.*?)\\]\\}")
let matches = regExp?.matches(in: htmlContext, range: htmlContext.toNSRange)
for match in matches! {
    print(htmlContext.substringFromNSRange(with: match.range)!)
}