SpringBoot2中使用@RequestHeader获取请求头的方法
作者:chushiyan
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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