SpringMVC/SpringBoot2中使用@RequestHeader获取请求头
springMVC/SpringBoot中提供了@RequestHeader注解用来获取请求头。
一、使用@RequestHeader获取请求头
（一）获取某一个请求头
例如，获取accept-language请求头：
@GetMapping("/getLanguage")
public Result test(@RequestHeader("accept-language") String language) {
// ......
return new Result(true, 600, language);
}
使用postman，没有设置accept-language请求头时，响应：
{
"timestamp": "2019-12-3T20:43:58.971+0000",
"status": 400,
"error": "Bad Request",
"message": "Missing request header 'accept-language' for method parameter of type String",
"path": "/getLanguage"
}
添加了accept-language请求头后，响应：
{
"flag": true,
"code": 600,
"message": "en-US,en;q=0.9,zh-CN;q=0.8,zh;q=0.7"
}
（二）获取数值型请求头
@GetMapping("/num")
public Result getNumber(@RequestHeader("my-number") int myNumber) {
return new Result(true, HttpStatus.OK.value(), String.valueOf(myNumber));
}
使用postman设置my-number请求头值为1，响应：
{
"flag": true,
"code": 200,
"message": "1"
}
（三）一次性获取所有请求头
1、使用Map接收所有请求头
@GetMapping("/getHeaders")
public Result listAllHeaders(@RequestHeader Map<String, String> headers) {
headers.forEach((key, value) -> {
// 日志中输出所有请求头
logger.info(String.format("Header '%s' = %s", key, value));
});
return new Result(true, HttpStatus.OK.value(), "");
}
使用postman请求该地址，控制台打印：
2019-12-03 21:10:35,993 INFO [http-nio-10000-exec-9] com.chushiyan.test.controller.HttpHeaderController: Header 'user-agent' = PostmanRuntime/7.20.1
2019-12-03 21:10:35,994 INFO [http-nio-10000-exec-9] com.chushiyan.test.controller.HttpHeaderController: Header 'accept' = */*
2019-12-03 21:10:35,994 INFO [http-nio-10000-exec-9] com.chushiyan.test.controller.HttpHeaderController: Header 'cache-control' = no-cache
2019-12-03 21:10:35,995 INFO [http-nio-10000-exec-9] com.chushiyan.test.controller.HttpHeaderController: Header 'postman-token' = 47dce6dd-c082-47b0-8867-720e45205aa1
2019-12-03 21:10:35,995 INFO [http-nio-10000-exec-9] com.chushiyan.test.controller.HttpHeaderController: Header 'host' = localhost:10000
2019-12-03 21:10:35,995 INFO [http-nio-10000-exec-9] com.chushiyan.test.controller.HttpHeaderController: Header 'accept-encoding' = gzip, deflate
2019-12-03 21:10:35,996 INFO [http-nio-10000-exec-9] com.chushiyan.test.controller.HttpHeaderController: Header 'connection' = keep-alive
2、使用MultiValueMap接收所有请求头
一个请求头存在多个值的时候，可以使用MultiValueMap接收所有请求头
@GetMapping("/getHeaders2")
public Result multiValue(@RequestHeader MultiValueMap<String, String> headers) {
headers.forEach((key, value) -> {
logger.info(String.format(
"Header '%s' = %s", key, value.stream().collect(Collectors.joining("/"))));
});
return new Result(true, HttpStatus.OK.value(), "");
}
3、使用HttpHeaders接收所用请求头
@GetMapping("/getBaseUrl")
public Result getBaseUrl(@RequestHeader HttpHeaders headers) {
// 获取到了所有的请求头，这里只是使用Host请求头
InetSocketAddress host = headers.getHost();
String url = "http://" + host.getHostName() + ":" + host.getPort();
return new Result(true, HttpStatus.OK.value(),url);
}
使用postman请求该地址，得到的响应：
{
"flag": true,
"code": 200,
"message": "http://localhost:10000"
}
二、@RequestHeader注解详解
@RequestHeader源码如下：
package org.springframework.web.bind.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.core.annotation.AliasFor;
/**
* Annotation which indicates that a method parameter should be bound to a web request header.
*
* <p>Supported for annotated handler methods in Spring MVC and Spring WebFlux.
*
* <p>If the method parameter is {@link java.util.Map Map<String, String>},
* {@link org.springframework.util.MultiValueMap MultiValueMap<String, String>},
* or {@link org.springframework.http.HttpHeaders HttpHeaders} then the map is
* populated with all header names and values.
*
* @author Juergen Hoeller
* @author Sam Brannen
* @since 3.0
* @see RequestMapping
* @see RequestParam
* @see CookieValue
*/
@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface RequestHeader {
/**
* Alias for {@link #name}.
*/
@AliasFor("name")
String value() default "";
/**
* The name of the request header to bind to.
* @since 4.2
*/
@AliasFor("value")
String name() default "";
/**
* Whether the header is required.
* <p>Defaults to {@code true}, leading to an exception being thrown
* if the header is missing in the request. Switch this to
* {@code false} if you prefer a {@code null} value if the header is
* not present in the request.
* <p>Alternatively, provide a {@link #defaultValue}, which implicitly
* sets this flag to {@code false}.
*/
boolean required() default true;
/**
* The default value to use as a fallback.
* <p>Supplying a default value implicitly sets {@link #required} to
* {@code false}.
*/
String defaultValue() default ValueConstants.DEFAULT_NONE;
}
（一）name、value属性
public Result test(@RequestHeader(name="accept-language") String language)
public Result test(@RequestHeader(value="accept-language") String language)
上面这两行代码效果相同。当然都可以省略为：（因为value是可以省略写的）
public Result test(@RequestHeader("accept-language") String language)
因为从源码中，可以看出name/value互为别名:
@AliasFor("name")
String value() default "";
@AliasFor("value")
String name() default "";
@AliasFor注解：
- @AliasFor在同一个注解中成对使用，表示两个属性互为别名。比如上面的，value和name就是互为别名。
- @AliasFor标签有一些使用限制，比如要求互为别名的属性的属性值类型、默认值都是相同的。
- 互为别名的注解必须成对出现，比如value属性添加了@AliasFor(“name”)，那么name属性就必须添加@AliasFor(“value”)。
（二）required属性
@GetMapping("/getHeader3")
public Result evaluateNonRequiredHeader(
@RequestHeader(value = "chushiyan", required = false) String header) {
return new Result(true,HttpStatus.OK.value(),"");
}
如果没有添加required = false，当请求头中没有这个chushiyan请求头时就会报错。
（三）defaultValue属性
可以使用defaultValue属性指定默认值
@GetMapping("/getHeader3")
public Result evaluateNonRequiredHeader(
@RequestHeader(value = "chushiyan", defaultValue = "hello") String header) {
return new Result(true,HttpStatus.OK.value(),"");
}
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