ThreadPoolExecutor线程池，通过自定义任务类和自定义拒绝策略，获取被拒绝任务的数据

public class CustomTask implements Runnable {
    private final int taskId; // 任务的 ID 或其他数据
    private final String taskData; // 任务的具体数据

    public CustomTask(int taskId, String taskData) {
        this.taskId = taskId;
        this.taskData = taskData;
    }

    @Override
    public void run() {
        // 模拟任务执行
        System.out.println("Executing task " + taskId + " with data: " + taskData);
        try {
            Thread.sleep(2000); // 模拟任务耗时
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }

    public int getTaskId() {
        return taskId;
    }

    public String getTaskData() {
        return taskData;
    }
}

import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ThreadPoolExecutor;

public class CustomRejectedExecutionHandler implements RejectedExecutionHandler {
    @Override
    public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
        if (r instanceof CustomTask) {
            CustomTask task = (CustomTask) r;
            // 获取任务数据
            int taskId = task.getTaskId();
            String taskData = task.getTaskData();

            // 处理被拒绝的任务
            System.err.println("Task rejected - ID: " + taskId + ", Data: " + taskData);

            // 可以在这里实现日志记录、重试逻辑等
        } else {
            System.err.println("Unknown task type rejected: " + r.toString());
        }
    }
}

import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

public class ThreadPoolExample {
    public static void main(String[] args) {
        // 创建线程池
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(2);
        executor.setMaxPoolSize(4);
        executor.setQueueCapacity(2);
        executor.setRejectedExecutionHandler(new CustomRejectedExecutionHandler());
        executor.initialize();

        // 提交任务
        for (int i = 0; i < 10; i++) {
            String taskData = "Data-" + i;
            CustomTask task = new CustomTask(i, taskData);
            executor.execute(task);
        }

        // 关闭线程池
        executor.shutdown();
    }
}

Executing task 0 with data: Data-0
Executing task 1 with data: Data-1
Task rejected - ID: 6, Data: Data-6
Task rejected - ID: 7, Data: Data-7
Task rejected - ID: 8, Data: Data-8
Task rejected - ID: 9, Data: Data-9