简介

本文介绍Java项目如何用代码手动获取SkyWalking的traceId。

引入依赖

<dependency>
    <groupId>org.apache.skywalking</groupId>
    <artifactId>apm-toolkit-trace</artifactId>
    <!-- 当前的最新版本,请与安装的服务器版本对应 -->
    <version>8.7.0</version>
</dependency>

代码获取traceId

在想获取traceId的地方加@Trace注解，然后调用TraceContext.traceId。

例：

@PostMapping("create")
@Trace
public Result create(Order order) {
    orderService.create(order);
    String traceId = TraceContext.traceId();
    return new Result().message("创建订单成功");
}

Trace所在包：import org.apache.skywalking.apm.toolkit.trace.Trace;

TraceContext所在包：import org.apache.skywalking.apm.toolkit.trace.TraceContext;

TraceContext可以获得spanId等其他信息：

项目应用

实际上，项目中不需要每个方法都加@Trace这个注解来获得traceId，只需要在全局响应的地方来获取即可。

下边展示项目中的实际用法（我是实测过的，可以获取到traceId）。

package com.example.common.advice;

import com.example.common.entity.Result;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.extern.slf4j.Slf4j;
import org.apache.skywalking.apm.toolkit.trace.Trace;
import org.apache.skywalking.apm.toolkit.trace.TraceContext;
import org.springframework.core.MethodParameter;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;

@Slf4j
@ControllerAdvice
public class GlobalResponseBodyAdvice implements ResponseBodyAdvice<Object> {
    @Override
    public boolean supports(MethodParameter returnType,
                            Class<? extends HttpMessageConverter<?>> converterType) {
        // 若接口返回的类型本身就是ResultWrapper，则无需操作，返回false
        // return !returnType.getParameterType().equals(ResultWrapper.class);
        return true;
    }

    @Override
    @ResponseBody
    @Trace
    public Object beforeBodyWrite(Object body, MethodParameter returnType,
                                  MediaType selectedContentType,
                                  Class<? extends HttpMessageConverter<?>> selectedConverterType,
                                  ServerHttpRequest request, ServerHttpResponse response) {

        String traceId = TraceContext.traceId();

        if (body instanceof String) {
            // 若返回值为String类型，需要包装为String类型返回。否则会报错
            try {
                ObjectMapper objectMapper = new ObjectMapper();
                Result<Object> result = new Result<>().data(body).traceId(traceId);
                return objectMapper.writeValueAsString(result);
            } catch (JsonProcessingException e) {
                throw new RuntimeException("序列化String错误");
            }
        } else if (body instanceof Result) {
            return ((Result)body).traceId(traceId);
        }

        return new Result<>().traceId(traceId).data(body);
    }
}