SpringBoot入门0x002：URL 映射

摘要：概述将某个请求映射到某个方法上这个注解可以加在某个或者某个方法上，如果加在上，则这个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。

将某个http请求映射到某个方法上

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

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 {

}

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

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

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

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"}

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

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

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

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
...

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

@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

@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"}

@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

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》