项目中后端服务经常需要前端传的请求头里的信息，今天给大家分享一下：

1、循环获取：

/**
     * 获取判断请求头的参数
     * @return
     */
    public static boolean checkHeaderName(){
        RequestAttributes ra = RequestContextHolder.getRequestAttributes();
        if(Objects.isNull(ra)){
            log.info("服务里RequestAttributes对象为空");
            return false;
        }
        ServletRequestAttributes sra = (ServletRequestAttributes) ra;
        HttpServletRequest request = sra.getRequest();
        Enumeration<String> enumeration = request.getHeaderNames();
        while (enumeration.hasMoreElements()) {
            String name = enumeration.nextElement();
            String value = request.getHeader(name);
            if(name.equals("accept-"+HeaderEnum.language.name()) && value.equals(HeaderEnum.language.head())){
                return true;
            }
            /**
             * 或者其他的业务处理
             */
        }
        return false;
    }

2、根据具体的key 获取：

/**
     *获取 判断请求头的参数
     * @return
     */
    public static boolean checkHeader(){
        RequestAttributes ra = RequestContextHolder.getRequestAttributes();
        if(Objects.isNull(ra)){
            log.info("服务里RequestAttributes对象为空");
            return false;
        }
        ServletRequestAttributes sra = (ServletRequestAttributes) ra;
        HttpServletRequest request = sra.getRequest();
        String head = request.getHeader("accept-"+HeaderEnum.language.name());
        if(head.equals(HeaderEnum.language.head())){
            return true;
        }
        /**
         * 或者其他的业务处理
         */
        return false;
    }

3、修改请求头信息：只能依靠反射原原理（HttpServletRequest中定义的对Header的操作全是只读，没有修改）。假设的场景是，需要对请求Header统一添加一个x-request-id，通过这个ID来从日志中定位每一个请求。

import java.io.IOException;
import java.lang.reflect.Field;
import java.util.UUID;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.RequestFacade;
import org.apache.tomcat.util.http.MimeHeaders;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
import org.springframework.util.ReflectionUtils;



@WebFilter(urlPatterns = "/*")
@Component
@Order(-999)
public class RequestIdGenFilter extends HttpFilter {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1787347739651657706L;
	
	@Override
	protected void doFilter(HttpServletRequest req, HttpServletResponse res, FilterChain chain) throws IOException, ServletException {
		try {
			// 从 RequestFacade 中获取 org.apache.catalina.connector.Request
			Field connectorField = ReflectionUtils.findField(RequestFacade.class, "request", Request.class);
			connectorField.setAccessible(true);
			Request connectorRequest = (Request) connectorField.get(req);
			
			// 从 org.apache.catalina.connector.Request 中获取 org.apache.coyote.Request
			Field coyoteField = ReflectionUtils.findField(Request.class, "coyoteRequest", org.apache.coyote.Request.class);
			coyoteField.setAccessible(true);
			org.apache.coyote.Request coyoteRequest = (org.apache.coyote.Request) coyoteField.get(connectorRequest);
			
			// 从 org.apache.coyote.Request 中获取 MimeHeaders
			Field mimeHeadersField =  ReflectionUtils.findField(org.apache.coyote.Request.class, "headers", MimeHeaders.class);
			mimeHeadersField.setAccessible(true);
			MimeHeaders mimeHeaders =  (MimeHeaders) mimeHeadersField.get(coyoteRequest);
			
			this.mineHeadersHandle(mimeHeaders);
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
		super.doFilter(req, res, chain);
	}
	
	protected void mineHeadersHandle (MimeHeaders mimeHeaders) {
		// 添加一个Header，随机生成请求ID
		mimeHeaders.addValue("x-request-id").setString(UUID.randomUUID().toString());;
		// 移除一个header
		mimeHeaders.removeHeader("User-Agent");
	}
}

参考    ： https://springboot.io/t/topic/3643

到此，关于请求头信息的增删改查分享完毕。