i want to make a wrapper class, that does pre-processing, executes the passed function, and then do some post-processing before returning the response. How i can write the wrapper class to accept function as parameter and invoke it?

@Autowired
private SomeService service;

@GetMapping("/path")
public CustomResponse(CustomRequest request){
  1. preprocess(request)
  2. CustomResponse response = service.functionA(request)
  3. postprocess(response)
  4. return response;
------------------------- vs --------------------------------
  1. return CustomWrapper.execute(request,???,response)
}

-- **Need help in writing this class.**

class CustomWrapper{
  void preprocess();
  ?? execute();
  void postprocess();
}

CodePudding user response：

This should be basically what you're looking for, if you want you can hard code the postprocessor and preprocessor so it can be used like your example, but this is a bit more general:

public class CustomProcessor {

    private Function<CustomRequest, CustomRequest> preprocessor;
    private Function<CustomResponse, ResponseEntity<CustomResponse>> postprocessor;

    public CustomProcessor(
            Function<CustomRequest, CustomRequest> preprocessor,
            Function<CustomResponse, ResponseEntity<CustomResponse>> postprocessor
    ) {
        this.preprocessor = preprocessor;
        this.postprocessor = postprocessor;
    }

    public ResponseEntity<CustomResponse> execute(CustomRequest request, Function<CustomRequest, CustomResponse> processor) {
        request = preprocessor.apply(request);
        CustomResponse response = processor.apply(request);
        return postprocessor.apply(response);
    }

}

CodePudding user response：

with help of @void void answer was able to achieve as required.

public class ControllerTemplate<Req, Res> {

  private static final Logger logger = LogManager.getLogger(ControllerTemplate.class);

  public Res execute(Req req, Function<Req, Res> processor) {
    preProcess(req);
    Res res = processor.apply(req);
    postProcess(res);
    return res;
  }

  private void postProcess(Res res) {
    logger.info("response body: {}", res);
  }

  private void preProcess(Req req) {
    logger.info("request body: {}", req);
  }
}

calling function

 @GetMapping("/logLevel")
  public String updateLogLevel(@RequestParam String level) {
    return new ControllerTemplate<String, String>()
        .execute(level, req -> log4jService.changeLogLevel(req));
  }