温故知新 – Spring MVC请求映射RequestMapping

清疚 2022-01-16 12:13 259阅读 0赞

**RequestMapping注解说明**

@RequestMapping注解的作用将Web请求映射到特定处理程序类和/或处理程序方法，这个注解可以用于类或者方法上，并通过属性value指定请求路径。用在Controller类上表示提供初步的URL请求映射信息，相对于Web应用的根目录，这是一个前置请求路径。用在Controller中方法上，表示提供详细的URL映射。如果Controller类上没有加RequestMapping注解，则方法上注解标记的URL则是相对于Web应用的根目录。

@RequestMapping注解提供以下几个属性：

name：用于指定映射器名称

value：用于指定映射路径，同path

path：用于指定映射路径，同value

method:用于指定请求类型：GET, POST, HEAD, OPTIONS, PUT, PATCH, DELETE, TRACE

params：指定请求的参数

headers：指定请求头部，源码示例：RequestMapping(value = “/something”, headers = “content-type=text/\*”)

consumes：指定处理请求提交的内容类型（Content-Type），例如application/json, text/html，只有在Content-Type匹配这些媒体类型之一时才会映射请求

produces：指定请求返回的内容类型 例如：produces = “application/json; charset=UTF-8”

**通过value属性指定映射路径**

**Controller类上使用RequestMapping注解**

在OrderController类上添加了注解RequestMapping(“order”)，表示所有对的请求必须是以“根目录/order” 开始

示例1的请求路径为：[http://localhost:8080/springMvcNext/order/orderinfo][http_localhost_8080_springMvcNext_order_orderinfo]

示例1 如果注释掉Controller上的@RequestMapping(“order”)，则对应的请求路径为：[http://localhost:8080/springMvcNext][http_localhost_8080_springMvcNext] /orderinfo

**Controller方法上使用RequestMapping注解**

1.**常用基础用法**

@Controller
    @RequestMapping("order") 
    public class OrderInfoController {
    
     //示例1
     @RequestMapping("orderinfo") 
     public ModelAndView OrderInfo1() {
     return new ModelAndView("order/info", "message", "OrderInfo");
     }
     //示例2 ：处理多个url映射
     @RequestMapping({"info","index"}) //或者@RequestMapping(value={"info","index"})
     public ModelAndView OrderInfo2() {
     return new ModelAndView("order/info","message", "OrderInfo2");
     } 
    
     //示例3
     @RequestMapping
     public ModelAndView OrderInfo3() { 
     return new ModelAndView("order/info","message", "OrderInfo3");
     }
    }

RequestMapping只配置value属性，不显示配置其他属性的情况下，value省略,直接填写URL映射信息即可,指定其他属性的情况下value属性必须明确填写

上例示例1的访问路径为： [http://localhost:8080/springMvcNext/order/orderinfo][http_localhost_8080_springMvcNext_order_orderinfo]

示例2：RequestMapping接口中value属性是一个数组，所有也支持传一个数组 示例2的访问路径：[http://localhost:8080/springMvcNext/order/index][http_localhost_8080_springMvcNext_order_index] 或者 [http://localhost:8080/springMvcNext/order/info][http_localhost_8080_springMvcNext_order_info]

示例3：当value为空时，表示该方法为类下默认的Action,示例3的访问路径为：[http://localhost:8080/springMvcNext/order][http_localhost_8080_springMvcNext_order]

2.**URL模板映射**

在RequestMapping注解中声明URI变量,并通过@PathVariable注解的方式访从实际请求URL中获取值，示例如下：

@Controller
    public class OrderInfoController {
     // 示例10 带占位符的URL
     @RequestMapping(value = "user/{userId}/order/{orderNumber}", method = RequestMethod.GET)
     public ModelAndView OrderInfo4(@PathVariable int userId,@PathVariable String orderNumber) {
     return new ModelAndView("order/info", "message", "userid:"+userId+" orderNumber:"+orderNumber);
     }
    }

示例10请求URL: [http://localhost:8080/springMvcNext/user/12/order/333][http_localhost_8080_springMvcNext_user_12_order_333] 当通过此URL发起请求时，SpringMVC将通过@PathVariable可以提取URL模板中的\{×××\}中的×××变量, URL变量会自动转换为对应的类型，无法转换的则返回错误，比如尝试用以下url访问：[http://localhost:8080/springMvcNext/user/xxx/order/333][http_localhost_8080_springMvcNext_user_xxx_order_333] 其中参数Userid=xxx，则发生错误：

![1240][]

**3.Ant风格的URL路径映射**

Ant风格通配符如下：

*   *  匹配一个字符
 *   *  匹配路径段中的零个或多个字符
 *   *  匹配零个或多个路径段

示例：

@Controller
    public class OrderInfoController {
     // 示例11 带占位符的URL
     @RequestMapping(value = "order*", method = RequestMethod.GET)
     //@RequestMapping(value = "order?", method = RequestMethod.GET)
     //@RequestMapping(value = "order/**", method = RequestMethod.GET)
     public ModelAndView OrderInfo5(String orderNumber) {
     return new ModelAndView("order/info", "message", "OrderInfo5");
     }
    }

示例11请求URL: [http://localhost:8080/springMvcNext/order/orderdexx?orderNumber=12][http_localhost_8080_springMvcNext_order_orderdexx_orderNumber_12] 可以匹配http://localhost:8080/springMvcNext/order/orderXXXXX?orderNumber=yyyy的所有请求

@RequestMapping(value = “order?”, method = RequestMethod.**GET**)可以匹配诸如 “…/ordera?orderNumber….” “…/orders?orderNumber….”

@RequestMapping(value = “order/\*\*”, method = RequestMethod.**GET**)可以匹配诸如 “…/order/aaa?orderNumber….” “…/order/bbb/ccc?orderNumber….”

另外 RequestMapping还支持正则表达式风格的URL路径映射，此处略过

**通过method属性指定请求类型**

RequestMapping提供的method属性请求谓词的类型，如下示例示例只接受GET请求

// 示例4
     @RequestMapping(value="detail",method=RequestMethod.GET) //也可直接使用 @GetMapping("detail")
     public ModelAndView Info() {
     return new ModelAndView("order/info", "message", "Info");
     }

对于每种请求类型，SpringMVC还提供了专用的注解：

@GetMapping

@PostMapping

@PutMapping

@DeleteMapping

@PatchMapping

**通过params指定参数名或参数值约束**

params属性可以限定请求参数包含特定的参数，也可限定参数值的约束，如下代码所示：

// 示例5 params 限定参数包含orderNumber
     @RequestMapping(value = "detail2", params = "orderNumber")
     public ModelAndView Detail2(String orderNumber) {
     return new ModelAndView("order/info", "message", orderNumber);
     }
     // 示例6 params 限定参数值
     @RequestMapping(value = "detail3", params = "orderNumber!=1222")
     public ModelAndView Detail3(String orderNumber) {
     return new ModelAndView("order/info", "message", orderNumber);
     }

示例5限定请求参数必须包含参数orderNumber,如果不包含名为orderNumber的参数，则拒绝访问:访问路径：[http://localhost:8080/springMvcNext/order/detail2?orderNumber=12][http_localhost_8080_springMvcNext_order_detail2_orderNumber_12]

示例6限定请求参数必须包含参数orderNumber并且参数值不能为1222 访问路径：[http://localhost:8080/springMvcNext/order/detail3?orderNumber=1222][http_localhost_8080_springMvcNext_order_detail3_orderNumber_1222] 时报错

![1240 1][]

**通过headers指定参数名或参数值约束**

RequestMapping提供的method属性可以指定请求头类型，只有请求数据头部类型符合指定的值时，才能正常访问

// 示例7 params 限定参数值
     @RequestMapping(value = "headtest",headers = "apikey=23131313") 
     //@RequestMapping(value = "headtest",headers= {"Accept=application/json"}) 
     public ModelAndView Header() {
     return new ModelAndView("order/info", "message", "Header");
     }

示例7限定请求头必须包含apikey:23131313才可以正常返回，直接访问，返回错误：

![1240 2][]

添加添加header信息apikey:23131313访问成功：

![1240 3][]

**通过consumes指定请求提交的内容类型（Content-Type）**

// 示例8 consumes 
     @RequestMapping(value = "consumes", method = RequestMethod.POST, consumes = "application/json")
     public ModelAndView Consumes(String orderNumber) {
     return new ModelAndView("order/info", "message", orderNumber);
     }

示例限定请求参数类型为application/json，表示该方法只处理请求Content-Type为application/json的请求：

下面通过抛postman测试：

设置请求参数格式为application/json，可以正常访问：

![1240 4][]

设置参数格式为x-form-urlencoded，返回错误，Http Status 415

![1240 5][]

**通过produces指定返回的内容类型（Content-Type）**

produces属性用于设定返回内容类型，并且满足以下条件：接受请求header中包含Accept的值与produces设定的值相同，或者接受的请求使用不显示设置accept值

// 示例8 produces 限定返回数据application/json
     @RequestMapping(value = "produces", method = RequestMethod.GET, produces = "application/json")
     public ModelAndView Produces(String orderNumber) {
     return new ModelAndView("order/info", "message", orderNumber);
     }

示例8 表示返回内容格式application/json ，当客户端设置的accept格式为text/json时，运行报错,Http status 406

![1240 6][]

当客户端设置的accept格式为application/json或者不设置accept值时，可以正常运行

[http_localhost_8080_springMvcNext_order_orderinfo]: http://localhost:8080/springMvcNext/order/orderinfo
[http_localhost_8080_springMvcNext]: http://localhost:8080/springMvcNext
[http_localhost_8080_springMvcNext_order_index]: http://localhost:8080/springMvcNext/order/index
[http_localhost_8080_springMvcNext_order_info]: http://localhost:8080/springMvcNext/order/info
[http_localhost_8080_springMvcNext_order]: http://localhost:8080/springMvcNext/order
[http_localhost_8080_springMvcNext_user_12_order_333]: http://localhost:8080/springMvcNext/user/12/order/333
[http_localhost_8080_springMvcNext_user_xxx_order_333]: http://localhost:8080/springMvcNext/user/xxx/order/333
[1240]: /images/20220114/bc4b3d88d81e419985f611ff28cfa499.png
[http_localhost_8080_springMvcNext_order_orderdexx_orderNumber_12]: http://localhost:8080/springMvcNext/order/orderdexx?orderNumber=12
[http_localhost_8080_springMvcNext_order_detail2_orderNumber_12]: http://localhost:8080/springMvcNext/order/detail2?orderNumber=12
[http_localhost_8080_springMvcNext_order_detail3_orderNumber_1222]: http://localhost:8080/springMvcNext/order/detail3?orderNumber=1222
[1240 1]: /images/20220114/823382c3a3854aa281c8a2b4af91c934.png
[1240 2]: /images/20220114/314bd87d36044796bf411170424c58fb.png
[1240 3]: /images/20220114/d7fbd4264d784cf1b83c239689257e76.png
[1240 4]: /images/20220114/69507597beb0471898a483023b0ac2a5.png
[1240 5]: /images/20220114/5b431bd3dd0d482387221c0f45ca314d.png
[1240 6]: /images/20220114/6792c59e293045a59a2492138af42e0b.png