@RequestMapping without parameter in Spring MVC

Question

I am trying to understand my project Code while learning Spring MVC.

In spring @RequestMapping annotation takes parameters. For example,

@RequestMapping(value="/something", method=RequestMethod.POST)
@RequestMapping(value="/index.html", method=RequestMethod.GET)
@RequestMapping("/index")
@RequestMapping(params="command=GETINFO")

My project uses annotations and it doesn't use any XML for mapping. I have a below structure of Controller.

@Controller
public class RuleStepController {
   private static final String ATTRIBUTE_BRANCH = "branch";
    private static final String ATTRIBUTE_EDIT_FORM = "editForm";
 .................
    @Autowired
    private RuleStepService ruleStepService;
    @Autowired
    private PopulationDao populationDao;

     @RequestMapping
    public void ruleStepEntForm(Long populationId, ModelMap model) {
     .....
     editForm.setStepEnt(stepDto);
    }

@RequestMapping
    public void ruleStepOrgCount(RuleStepOrgSearchForm searchForm, ModelMap model){
      .......
model.addAttribute("searchForm", searchForm);
    }

@RequestMapping
    public String ruleStepMgrForm() {
        logger.debug(String.format("ruleStepMgrForm"));
        return "forward:/employee/employeeSearchForm.view?relationshipId=0&roleId=0&formId=stepMgr";
    }

I would like to understand what would be significance of @RequestMapping when it doesn't carry any parameter?

What is use of @AutoWired ?

Answer 1

1. With annotation @RequestMapping you can bind request parameters with several way:

   URI Template Patterns, use annotation @PathVariable

   @RequestMapping(value="/owners/{ownerId}", method=RequestMethod.GET)
   public String findOwner(@PathVariable String ownerId, Model model) {
       Owner owner = ownerService.findOwner(ownerId);
       model.addAttribute("owner", owner);
       return "displayOwner";
   }
   

   Request Parameters and Header Values

   @Controller
   @RequestMapping("/owners/{ownerId}")
   public class RelativePathUriTemplateController {
   
       @RequestMapping(value = "/pets/{petId}", method = RequestMethod.GET, params = "myParam=myValue")
       public void findPet(@PathVariable String ownerId, @PathVariable String petId, Model model) {
           // implementation omitted
       }
   }
   

   use @RequestParam

   @Controller
   @RequestMapping("/pets")
   @SessionAttributes("pet")
   public class EditPetForm {
   
       @RequestMapping(method = RequestMethod.GET)
       public String setupForm(@RequestParam("petId") int petId, ModelMap model) {
           Pet pet = this.clinic.loadPet(petId);
           model.addAttribute("pet", pet);
           return "petForm";
       }
   }
   

   Mapping the request body with the @RequestBody annotation

   @RequestMapping(value = "/something", method = RequestMethod.PUT)
   public void handle(@RequestBody String body, Writer writer) throws IOException {
       writer.write(body);
   }
   

2. Autowiring

   @Autowired
   private RuleStepService ruleStepService;
   

   The Spring Container has created the bean ruleStepService before. If you need use this bean in your class you only need declare as above and the container will inject the bean into your class . You don't need declare like;

   RuleStepService ruleStepService =new RuleStepService(). 
   

   Container will find the bean name ruleStepService or the bean has type RuleStepService ( based on the strategy in configuration )