为什么用
因为jdk中的ThreadLocal，InheritableThreadLocal 无法在父子线程，父线程与线程池之间变量的传递

关键代码

private static TransmittableThreadLocal<String> threadLocal = new TransmittableThreadLocal<>();

// 创建一个固定大小的线程池，实际中肯定不这样建，demo用下
        ExecutorService executorService = Executors.newFixedThreadPool(2);
// 使用TtlExecutors包装线程池，关键点
        ExecutorService ttlExecutorService = TtlExecutors.getTtlExecutorService(executorService);

1 pom.xml配置

<dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>transmittable-thread-local</artifactId>
            <version>2.14.2</version>
</dependency>

2 示例

package org.example.controller;

import com.alibaba.ttl.TransmittableThreadLocal;
import com.alibaba.ttl.threadpool.TtlExecutors;
import java.util.ArrayList;
import java.util.concurrent.*;

public class TtlExecutorsDemo {
    private static TransmittableThreadLocal<String> threadLocal = new TransmittableThreadLocal<>();

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        // 创建一个固定大小的线程池
        ExecutorService executorService = Executors.newFixedThreadPool(2);
        // 使用TtlExecutors包装线程池
        ExecutorService ttlExecutorService = TtlExecutors.getTtlExecutorService(executorService);

        // 在主线程中设置TransmittableThreadLocal的值
        threadLocal.set("工艺");

        // 提交任务到线程池中
        ArrayList<Future<String>> futures = new ArrayList<>();

        for (int i = 0; i <2 ; i++) {
            Future<String> future = ttlExecutorService.submit(() -> {
                TimeUnit.SECONDS.sleep(2); // 模拟耗时操作
                String value = threadLocal.get();
                System.out.println(Thread.currentThread().getName() + "---------" + value);
                return value;
            });
            futures.add(future);
        }

      futures.forEach(future ->{
          try {
              System.out.println("future.get() = " + future.get());
          } catch (InterruptedException e) {
              throw new RuntimeException(e);
          } catch (ExecutionException e) {
              throw new RuntimeException(e);
          }
      });

        // 关闭线程池
        ttlExecutorService.shutdown();

        while (!ttlExecutorService.awaitTermination(1, TimeUnit.SECONDS)) {
            // 等待直到所有任务完成
        }
    }
}

3 效果

pool-1-thread-1---------工艺
pool-1-thread-2---------工艺
future.get() = 工艺
future.get() = 工艺