@RequestMapping 详解

RequestMapping是一个用来处理请求地址映射的注解，可用于类或方法上。用于类上，表示类中的所有响应请求的方法都是以该地址作为父路径。
RequestMapping注解有六个属性，下面我们把她分成三类进行说明。

三类

1、 value,method

value：指定请求的实际地址，指定的地址可以是URI Template 模式（后面将会说明）；
method：指定请求的method类型， GET、POST、PUT、DELETE等；

2、 consumes,produces

consumes： 指定处理请求的提交内容类型（Content-Type），例如application/json, text/html;
produces: 指定返回的内容类型，仅当request请求头中的(Accept)类型中包含该指定类型才返回；

3、 params，headers；

params： 指定request中必须包含某些参数值是，才让该方法处理。
headers： 指定request中必须包含某些指定的header值，才能让该方法处理请求。

示例：

1、value / method 示例:

默认RequestMapping("....str...")即为value的值；

@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";
    }
}  

注意: value的uri值为以下三类：

A） 可以指定为普通的具体值；
B) 可以指定为含有某变量的一类值(URI Template Patterns with Path Variables)；
C) 可以指定为含正则表达式的一类值( URI Template Patterns with Regular Expressions);

//[1].example B)
@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";
}  

//[2].example C)
@RequestMapping("/spring-web/{symbolicName:[a-z-]+}-{version:\d\.\d\.\d}.{extension:\.[a-z]}")
  public void handle(@PathVariable String version, @PathVariable String extension) {
    // ...
  }
}  

2 、consumes、produces 示例

//[1].cousumes的样例：方法仅处理request Content-Type为“application/json”类型的请求。
@Controller
@RequestMapping(value = "/pets", method = RequestMethod.POST, consumes="application/json")
public void addPet(@RequestBody Pet pet, Model model) {
    // implementation omitted
}  

//[2].produces的样例：方法仅处理request请求中Accept头中包含了"application/json"的请求，同时暗示了返回的内容类型为application/json;
@Controller
@RequestMapping(value = "/pets/{petId}", method = RequestMethod.GET, produces="application/json")
@ResponseBody
public Pet getPet(@PathVariable String petId, Model model) {
    // implementation omitted
}  

3、 params、headers 示例

//params的样例：仅处理请求中包含了名为“myParam”，值为“myValue”的请求；
@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
  }
}  

//headers的样例：仅处理request的header中包含了指定“Refer”请求头和对应值为"http://www.ifeng.com/"的请求；
@Controller
@RequestMapping("/owners/{ownerId}")
public class RelativePathUriTemplateController {  

@RequestMapping(value = "/pets", method = RequestMethod.GET, headers="Referer=http://www.ifeng.com/")
  public void findPet(@PathVariable String ownerId, @PathVariable String petId, Model model) {
    // implementation omitted
  }
}