Spring MVC学习笔记（1）

spring mvc是spring framework的一部分。

1.请求处理流程

2.控制器(controller)与注解(annotation)

控制器中常用注解： @Controller ， @RequestMapping，其中@RequestMapping可以用在类上，也可用在方法上。

@Controller
@RequestMapping("/appointments")
public class AppointmentsController {

    private final AppointmentBook appointmentBook;
    
    @Autowired
    public AppointmentsController(AppointmentBook appointmentBook) {
        this.appointmentBook = appointmentBook;
    }

    @RequestMapping(method = RequestMethod.GET)
    public Map<String, Appointment> get() {
        return appointmentBook.getAppointmentsForToday();
    }

    @RequestMapping(value="/{day}", method = RequestMethod.GET)
    public Map<String, Appointment> getForDay(@PathVariable @DateTimeFormat(iso=ISO.DATE) Date day, Model model) {
        return appointmentBook.getAppointmentsForDay(day);
    }

    @RequestMapping(value="/new", method = RequestMethod.GET)
    public AppointmentForm getNewForm() {
        return new AppointmentForm();
    }

    @RequestMapping(method = RequestMethod.POST)
    public String add(@Valid AppointmentForm appointment, BindingResult result) {
        if (result.hasErrors()) {
            return "appointments/new";
        }
        appointmentBook.addAppointment(appointment);
        return "redirect:/appointments";
    }
}

 getForDay() 方法提供了 @RequestMapping注解的另一种用法：URI 模板（templates）。

URI 模板是一个象 URI 的字符串 ，包含一个或多个变量名。 当你提交变量的值时, 这个模板变成一个 URI。例如：

http://www.example.com/users/{userid}。

使用方法参数 注解@PathVariable 表示一个方法参数绑定到一个URI模板的变量。

例如：

@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";
}

@RequestParam：把请求参数绑定到方法参数

@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";
}
// ...

   设置参数可选：@RequestParam(value="id", required=false)

@ModelAttribute：放在方法参数前时，可以把一个模型属性映射到指定的注解的方法参数。放在方法级别时，提供模型的引用数据

@Controller
@RequestMapping("/owners/{ownerId}/pets/{petId}/edit")
@SessionAttributes("pet")
public class EditPetForm {
// ...
@ModelAttribute("types")
public Collection<PetType> populatePetTypes() {
return this.clinic.getPetTypes();
}
@RequestMapping(method = RequestMethod.POST)
public String processSubmit(
@ModelAttribute("pet") Pet pet,
BindingResult result, SessionStatus status) {
new PetValidator().validate(pet, result);
if (result.hasErrors()) {
return "petForm";

@SessionAttributes：指定存储在session中的属性
@CookieValue：映射cookie值