@RequestMapping注解实践
1.引言
springMVC提供了http请求的注解，功能强大，对http协议的封装实现妙到恰好。本文重点学习@RequestMapping注解，一起感受springMVC的强大和精深。
http协议有post和put方式提交数据，但是它们到底有什么不同呢？通过实践理解它们的不同之处。
2.简介
@RequestMapping
它是一个用来处理请求地址映射的注解。可用于类和方法上。用于类上，表示类中所有请求的方法都是以该地址作为父路径。RequestMapping有6个属性，分三类说明：
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)类型中包含指定类型才返回；
3.params,headers
params:指定request中必须包含某些参数值，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。
4.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";
}
}
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）
exampleB
@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";
}
exampleC
@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
consumes的示例：
@Controller
@RequestMapping(value = "/pets", method = RequestMethod.POST, consumes="application/json")
public void addPet(@RequestBody Pet pet, Model model) {
// implementation omitted
}
方法仅处理request Content-Type为"application/json"类型的请求。
produces的示例：
@Controller
@RequestMapping(value = "/pets/{petId}", method = RequestMethod.GET, produces="application/json")
@ResponseBody
public Pet getPet(@PathVariable String petId, Model model) {
// implementation omitted
}
方法仅处理request请求总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;
3.params、headers示例
params的示例：
@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
}
}
仅处理请求中包含了名为“myParam”,职位“myValue”的请求；
headers的示例：
@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
}
}
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；
实践1
@RequestMapping(value="userInfo",params={"param"},method=RequestMethod.PUT,consumes="application/json",produces="application/json")
@ResponseBody
public String userInfo(String param,HttpServletRequest request,HttpServletResponse response,HttpSession session){
log.info(param);
return param;
}
发送param参数给服务器，param参数符合json格式。