分布式链路ID实现

实现原理

api入口或者网关处生成traceId，调用服务时优先检查是否头部带有traceId，有则复用，没有则生成

实现方式

处理api相关traceId

1.通过filter复用或者生成traceId，并且将traceId输入到响应头中

java 复制代码

import java.io.IOException;
import java.util.UUID;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.slf4j.MDC;
import org.springframework.web.filter.OncePerRequestFilter;

public class TraceIdFilter extends OncePerRequestFilter {
    public TraceIdFilter() {
    }

    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        String traceId = request.getHeader("X-Trace-Id");
        if (traceId == null) {
            traceId = this.generateTraceId();
        }

        MDC.put("traceId", traceId);
        response.setHeader("X-Trace-Id", traceId);

        try {
            filterChain.doFilter(request, response);
        } finally {
            MDC.clear();
        }

    }

    private String generateTraceId() {
        return UUID.randomUUID().toString().replace("-", "");
    }
}

2、在对应项目中启用filter

java 复制代码

@Configuration
public class WebFilterConfig {

    @Bean
    public FilterRegistrationBean<TraceIdFilter> loggingFilter() {
        FilterRegistrationBean<TraceIdFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new TraceIdFilter());
        registrationBean.addUrlPatterns("/*"); // 只对特定 URL 匹配
        return registrationBean;
    }
}

Feign调用时传递traceId

1、声明拦截器（feign调用时从mdc获取traceId放入请求头中）

java 复制代码

import feign.RequestInterceptor;
import feign.RequestTemplate;
import org.slf4j.MDC;

public class FeIgnMCDInterceptor implements RequestInterceptor {
    public FeIgnMCDInterceptor() {
    }

    public void apply(RequestTemplate template) {
        String traceId = MDC.get("traceId");
        if (traceId != null) {
            template.header("X-Trace-Id", new String[]{traceId});
        }

    }
}

2、启用拦截器

java 复制代码

// 任意位置注册为springbean即可
@Bean
public FeIgnMCDInterceptor feIgnMCDInterceptor() {
    return new FeIgnMCDInterceptor();
}

日志配置文件中打印traceId

XML 复制代码

<!-- 日志输出格式 -->
<property name="log.pattern" value="%d{yyyy-MM-dd HH:mm:ss.SSS} [${application_name}] [%X{traceId}] [%thread] %-5level %logger - [%method,%line] - %msg%n" />