@GetMapping("/getLanguage")
public Result test(@RequestHeader("accept-language") String language) {
    // ......
    
    return new Result(true, 600, language);
}

{
    "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"
}

{
    "flag": true,
    "code": 600,
    "message": "en-US,en;q=0.9,zh-CN;q=0.8,zh;q=0.7"
} 

@GetMapping("/num")
public Result getNumber(@RequestHeader("my-number") int myNumber) {
    return new Result(true, HttpStatus.OK.value(), String.valueOf(myNumber));
}

{
    "flag": true,
    "code": 200,
    "message": "1"
}

@GetMapping("/getHeaders")
public Result listAllHeaders(@RequestHeader Map<String, String> headers) {
    headers.forEach((key, value) -> {
        // 日志中輸出所有請(qǐng)求頭
        logger.info(String.format("Header '%s' = %s", key, value));
    });
    return new Result(true, HttpStatus.OK.value(), "");
}

@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(), "");
}

@GetMapping("/getBaseUrl")
public Result getBaseUrl(@RequestHeader HttpHeaders headers) {
    // 獲取到了所有的請(qǐng)求頭，這里只是使用Host請(qǐng)求頭
    InetSocketAddress host = headers.getHost();
    String url = "http://" + host.getHostName() + ":" + host.getPort();
    return new Result(true, HttpStatus.OK.value(),url);
}

{
    "flag": true,
    "code": 200,
    "message": "http://localhost:10000"
}

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&lt;String, String&gt;},
 * {@link org.springframework.util.MultiValueMap MultiValueMap&lt;String, String&gt;},
 * 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;

}

public Result test(@RequestHeader(name="accept-language") String language)
public Result test(@RequestHeader(value="accept-language") String language)

public Result test(@RequestHeader("accept-language") String language)

   @AliasFor("name")
   String value() default "";

   @AliasFor("value")
   String name() default "";

@GetMapping("/getHeader3")
public Result evaluateNonRequiredHeader(
        @RequestHeader(value = "chushiyan", required = false) String header) {

    return new Result(true,HttpStatus.OK.value(),"");
}

@GetMapping("/getHeader3")
public Result evaluateNonRequiredHeader(
        @RequestHeader(value = "chushiyan", defaultValue = "hello") String header) {

    return new Result(true,HttpStatus.OK.value(),"");
}