Spring PathVariable在外部使用

Question

I have Spring rest controller that provides operations on Project entity. All methods use same entity accessing code. I don't want to copy&paste @PathVariable parameters in all methods, so I've made something like this.

@RestController
@RequestMapping("/projects/{userName}/{projectName}")
public class ProjectController {


  @Autowired
  ProjectService projectService;
  @Autowired
  protected HttpServletRequest context;


  protected Project project() {
    // get {userName} and {projectName} path variables from request string
    String[] split = context.getPathInfo().split("/");
    return projectService.getProject(split[2], split[3]);
  }


  @RequestMapping(method = GET)
  public Project get() {
    return project();
  }


  @RequestMapping(method = GET, value = "/doSomething")
  public void doSomething() {
    Project project = project();
    // do something with project
  }

  // more @RequestMapping methods using project()

}

Is it possible to autowire path variables into controller by annotation so I don't have to split request path and get parts of it from request string for project() method?

Answer 1

In order to do custom binding from request you've got to implement your own HandlerMethodArgumentResolver (it's a trivial example without checking if path variables actually exist and it's also global, so every time you will try to bind to Project class this argument resolver will be used):

class ProjectArgumentResolver implements HandlerMethodArgumentResolver {
    @Override
    public boolean supportsParameter(MethodParameter methodParameter) {
        return methodParameter.getParameterType().equals(Project.class);
    }

    @Override
    public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
        Map<String, String> uriTemplateVars = (Map<String, String>) webRequest.getAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, RequestAttributes.SCOPE_REQUEST);

        return getProject(uriTemplateVars.get("userName"), uriTemplateVars.get("projectName"));
    }

    private Project getProject(String userName, String projectName) {
        // replace with your custom Project loading logic 
        Project project = new Project(userName, projectName); 

        return project;
    }
}

and register it using WebMvcConfigurerAdapter :

@Component
public class CustomWebMvcConfigurerAdapter extends WebMvcConfigurerAdapter {
    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
        argumentResolvers.add(new ProjectArgumentResolver());
    }
}

In your controller you have to put Project as a method argument, but do not annotate it with @PathVariable:

@Controller
@RequestMapping("/projects/{userName}/{projectName}")
public class HomeController {
    @RequestMapping(method = RequestMethod.GET)
    public void index(Project project){
        // do something
    }
}