以下是使用ThreadLocal实现用户会话隔离的完整示例，模拟Web应用中每个请求线程的用户会话隔离：

public class UserSessionHolder {

    private static final ThreadLocal sessionHolder = new ThreadLocal<>();

    public static void set(UserSession session) {

        sessionHolder.set(session);

    }

    public static UserSession get() {

        return sessionHolder.get();

    }

    public static void clear() {

        sessionHolder.remove();

    }

}

 class UserSession {

    private String userId;

    private String username;

    private long loginTime;

    // 构造方法、getter和setter

    public UserSession(String userId, String username) {

        this.userId = userId;

        this.username = username;

        this.loginTime = System.currentTimeMillis();

    }

    // 省略getter/setter方法...

}

 class RequestHandler implements Runnable {

    private final UserSession session;

    public RequestHandler(UserSession session) {

        this.session = session;

    }

    @Override

    public void run() {

        try {

            UserSessionHolder.set(session);

            System.out.println(Thread.currentThread().getName() 

                + " 处理用户: " + UserSessionHolder.get().getUsername());

            // 模拟业务处理

            Thread.sleep(500);

        } catch (InterruptedException e) {

            e.printStackTrace();

        } finally {

            UserSessionHolder.clear();

        }

    }

}

 class Application {

    public static void main(String[] args) {

        // 模拟多个用户请求

        ExecutorService executor = Executors.newFixedThreadPool(3);

        for (int i = 1; i <= 5; i++) {

            UserSession session = new UserSession("UID" + i, "User" + i);

            executor.execute(new RequestHandler(session));

        }

        executor.shutdown();

    }

}

该实现通过ThreadLocal为每个线程创建独立的用户会话副本，确保多线程环境下会话数据隔离。UserSessionHolder作为会话容器，RequestHandler模拟Web请求处理流程，最后在主程序中测试多用户场景。注意在finally块中清理ThreadLocal防止内存泄漏。