MDC是基于@Slf4j的
MDC是什么:（简单理解）线程上下文
日志链路追踪解决了什么：
1:增强了代码的调试机制
2：重点：实现了 多线程环境下 代码链路追踪基础版本（不涉及异步）
1：引入日志依赖（slf4j的）
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-logging</artifactId>
</dependency>2：引入日志配置
📎logback-spring.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.wm.file</groupId>
<artifactId>ExportExcelData</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<!--Spring Boot 实现日志链路追踪，无需引入组件，让日志定位更方便！-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-logging</artifactId>
</dependency>
<dependency>
<groupId>cn.afterturn</groupId>
<artifactId>easypoi-annotation</artifactId>
<version>4.1.0</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.24</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>transmittable-thread-local</artifactId>
<version>2.14.2</version>
</dependency>
<!--测试-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.1</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>3：编写拦截器，基于MDC给请求添加TriceID
public class LogInterceptor implements HandlerInterceptor {
private static final String TRACE_ID = "TRACE_ID";
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
String tid = UUID.randomUUID().toString().replace("-", "");
//可以考虑让客户端传入链路ID，但需保证一定的复杂度唯一性；如果没使用默认UUID自动生成
if (!StringUtils.isEmpty(request.getHeader("TRACE_ID"))) {
tid = request.getHeader("TRACE_ID");
}
MDC.put(TRACE_ID, tid);
return true;
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler,
@Nullable Exception ex) {
MDC.remove(TRACE_ID);
}
}原理详解
基础版问题（异步导致子线程triceID失效）
不涉及异步正常打印trice
异步方式会导致triceID失效
优化版：线程池解决异步问题(多加个线程池)
@Configuration
public class WebConfigurerAdapter implements WebMvcConfigurer {
@Bean
public LogInterceptor logInterceptor() {
return new LogInterceptor();
}
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(logInterceptor()).addPathPatterns("/**");
//可以具体制定哪些需要拦截，哪些不拦截，其实也可以使用自定义注解更灵活完成
// .excludePathPatterns("/testxx.html");
}
}
package com.wm.file.config;
import org.slf4j.MDC;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.Callable;
public final class ThreadMdcUtil {
private static final String TRACE_ID = "TRACE_ID";
// 获取唯一性标识
public static String generateTraceId() {
return UUID.randomUUID().toString();
}
public static void setTraceIdIfAbsent() {
if (MDC.get(TRACE_ID) == null) {
MDC.put(TRACE_ID, generateTraceId());
}
}
/**
* 用于父线程向线程池中提交任务时，将自身MDC中的数据复制给子线程
*
* @param callable
* @param context
* @param <T>
* @return
*/
public static <T> Callable<T> wrap(final Callable<T> callable, final Map<String, String> context) {
return () -> {
if (context == null) {
MDC.clear();
} else {
MDC.setContextMap(context);
}
setTraceIdIfAbsent();
try {
return callable.call();
} finally {
MDC.clear();
}
};
}
/**
* 用于父线程向线程池中提交任务时，将自身MDC中的数据复制给子线程
*
* @param runnable
* @param context
* @return
*/
public static Runnable wrap(final Runnable runnable, final Map<String, String> context) {
return () -> {
if (context == null) {
MDC.clear();
} else {
MDC.setContextMap(context);
}
setTraceIdIfAbsent();
try {
runnable.run();
} finally {
MDC.clear();
}
};
}
}package com.wm.file.config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableAsync;
import java.util.concurrent.Executor;
@Configuration
@EnableAsync
public class ThreadPoolConfig {
/**
* 声明一个线程池
*
* @return 执行器
*/
@Bean("MyExecutor")
public Executor asyncExecutor() {
MyThreadPoolTaskExecutor executor = new MyThreadPoolTaskExecutor();
//核心线程数5：线程池创建时候初始化的线程数
executor.setCorePoolSize(5);
//最大线程数5：线程池最大的线程数，只有在缓冲队列满了之后才会申请超过核心线程数的线程
executor.setMaxPoolSize(5);
//缓冲队列500：用来缓冲执行任务的队列
executor.setQueueCapacity(500);
//允许线程的空闲时间60秒：当超过了核心线程出之外的线程在空闲时间到达之后会被销毁
executor.setKeepAliveSeconds(60);
//线程池名的前缀：设置好了之后可以方便我们定位处理任务所在的线程池
executor.setThreadNamePrefix("asyncJCccc");
executor.initialize();
return executor;
}
}
@Configuration
public class WebConfigurerAdapter implements WebMvcConfigurer {
@Bean
public LogInterceptor logInterceptor() {
return new LogInterceptor();
}
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(logInterceptor()).addPathPatterns("/**");
//可以具体制定哪些需要拦截，哪些不拦截，其实也可以使用自定义注解更灵活完成
// .excludePathPatterns("/testxx.html");
}
}加入这四个线程操作文件，
异步执行父线程将triceID传递给子线程
启动加载顺序
请求进来的流程：
1：给线程设置triceID
2：感知到异步（@aysc）触发线程池(我们重写的)
3:父线程赋值TriceID给子线程（子线程调用携带父线程的triceID）
