SpringBoot入门0x002：URL 映射

0x000 概述

将某个http请求映射到某个方法上

0x001 @RequestMapping

这个注解可以加在某个Controller或者某个方法上，如果加在Controller上，则这个Controller中的所有路由映射都将会加上这个前缀（下面会有栗子），如果加在方法上，则没有前缀（下面也有栗子）。

@RequestMapping有以下属性

• value: 请求的URL的路径
• path: 和value一样
• method: 请求的方法
• consumes: 允许的媒体类型，也就是Content-Type
• produces: 相应的媒体类型，也就是Accept
• params: 请求参数
• headers: 请求头部

0x002 路由匹配

1. 首先编写Controller，Controller头部的@RestController将这个控制器标注为Rest控制器：

   package com.lyxxxx.rest.controller;
   
   import org.springframework.web.bind.annotation.RequestMapping;
   import org.springframework.web.bind.annotation.RestController;
   
   @RestController
   public class HelloController {
   
   }
   

2. 添加方法，并添加URL匹配：

       @RequestMapping()
       public Object hello() {
           return "hello";
       }
       

   说明：上面添加了一个方法，名为hello，没有给定任何的属性，则默认匹配所有URL，方法为GET，所以我们可以直接使用GET方式来访问该路由

   $ curl 127.0.0.1:8080
   hello
   $ curl 127.0.0.1:8080/user
   hello
   $ curl 127.0.0.1:8080/user/1
   hello

3. 精确匹配

   @RequestMapping(value = "/hello2")
   public Object hello2() {
       return "hello2";
   }

   说明：上面将value设置为hello2，所以访问hello2将会执行hello2方法

   $ curl 127.0.0.1:8080/hello2
   hello2

4. 字符模糊匹配

   @RequestMapping(value = "/hello3/*")
   public Object hello3() {
       return "hello3";
   }

   说明：上面将value设置为/hello3/*,*为匹配所有字符，也就是访问hello3下的所有URL都将匹配该防范

   $ curl 127.0.0.1:8080/hello3/user
   hello3
    curl 127.0.0.1:8080/hello3/1
   hello3

5. 单字符模糊匹配

   $ curl 127.0.0.1:8080/hello4/1
   hello4

   说明：上面将value设置为/hello4/?,?为匹配单个字符，匹配hello4/1，但是不会匹配hello4/11

   $ curl 127.0.0.1:8080/hello4/1
   hello4
   $ curl 127.0.0.1:8080/hello4/12
   {"timestamp":"2018-07-25T05:29:39.105+0000","status":404,"error":"Not Found","message":"No message available","path":"/hello4/12"}

6. 全路径模糊匹配

   @RequestMapping(value = "/hello5/**")
   public Object hello5() {
       return "hello5";
   }

   说明：上面将value设置为/hello5/**,**为匹配所有路径，所以hello5下面的所有路由都将匹配这个方法

   $ curl 127.0.0.1:8080/hello5
   hello5
   $ curl 127.0.0.1:8080/hello5/user/1
   hello5

7. 多个路径匹配

   @RequestMapping(value = {"/hello6", "/hello6/1"})
   public Object hello6() {
       return "hello6";
   }

   $ curl 127.0.0.1:8080/hello6
   hello6
   $ curl 127.0.0.1:8080/hello6/1
   hello6F

8. 读取配置

   // resources/application.properties
   
   app.name=hello7
   
   // com.lyxxxx.rest.controller.HelloController
   
   @RequestMapping(value = "${app.name}")
   public Object hello7() {
       return "hello7";
   }

   $ curl 127.0.0.1:8080/hello7
   hello7

0x003 方法匹配

匹配请求中的method，写在RequestMethod中的枚举值：

• GET
• HEAD
• POST
• PUT
• PATCH
• DELETE
• OPTIONS
• TRACE

package com.lyxxxx.rest.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MethodController {
    @RequestMapping(path = "method/get", method = RequestMethod.GET)
    public Object get() {
        return "get";
    }

    @RequestMapping(path = "method/head", method = RequestMethod.HEAD)
    public Object head() {
        return "head";
    }

    @RequestMapping(path = "method/post", method = RequestMethod.POST)
    public Object post() {
        return "post";
    }

    @RequestMapping(path = "method/put", method = RequestMethod.PUT)
    public Object put() {
        return "put";
    }

    @RequestMapping(path = "method/patch", method = RequestMethod.PATCH)
    public Object patch() {
        return "patch";
    }

    @RequestMapping(path = "method/delete", method = RequestMethod.DELETE)
    public Object delete() {
        return "delete";
    }

    @RequestMapping(path = "method/options", method = RequestMethod.OPTIONS)
    public Object options() {
        return "options";
    }

    @RequestMapping(path = "method/trace", method = RequestMethod.TRACE)
    public Object trace() {
        return "trace";
    }


}

$ curl -X GET  127.0.0.1:8080/method/get
get
$ curl -X POST 127.0.0.1:8080/method/post
post
$ curl -X DELETE 127.0.0.1:8080/method/delete
delete
$ curl -X PUT 127.0.0.1:8080/method/put
put
...

0x003 params 匹配

除了可以匹配URL和method之外，还可以匹配params

package com.lyxxxx.rest.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ParamsController {
    @RequestMapping(path = "/params", params = "userId=1")
    public Object params() {
        return "params";
    }
}

$ curl 127.0.0.1:8080/params?userId=1
params

0x004 header 匹配

@RestController
public class HeaderController {
    @RequestMapping(path = "/headers", headers = "userId=1")
    public Object headers() {
        return "headers";
    }
}

$ curl 127.0.0.1:8080/headers
{"timestamp":"2018-08-01T06:11:40.037+0000","status":404,"error":"Not Found","message":"No message available","path":"/headers"}
$ curl 127.0.0.1:8080/headers -H "userId:1"
headers

0x005 consumes 匹配

@RestController
public class ConsumesController {

    @RequestMapping(value = "consumes",consumes = "application/json")
    public Object json() {
        return "consumes";
    }
}

$ curl 127.0.0.1:8080/consumes -H "Content-Type:application/json"
consumes
$ curl 127.0.0.1:8080/consumes -H "Content-Type:none"
{"timestamp":"2018-08-01T06:15:10.919+0000","status":415,"error":"Unsupported Media Type","message":"Invalid mime type \"none\": does not contain '/'","path":"/consumes"}

0x006 produces 匹配

@RestController
public class ProducesController {
    @RequestMapping(value = "/produces", produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
    public Object produces() {
        return "produces";
    }
}

$ curl 127.0.0.1:8080/produces 
produces
$ curl 127.0.0.1:8080/produces -H "Accept:text"
// 空

0x007 说明

以上参考数据：《Spring Boot2精髓 从构建小系统到架构分部署大系统》