前言

在异步任务中，我们通常会遇到子任务获取当前用户的场景。我们可能会采取ThreadLocal来存储主线程传递的用户信息。然后在业务开始时set，业务结束时remove，来保证不会出现OOM的场景。

基础写法

@SpringBootTest
public class UserAsyncTransmitTest {@Resourceprivate Executor myTaskExecutor;@Resourceprivate TestService testService;@Testvoid test() throws InterruptedException {LoginUser loginUser = LoginUser.builder().username("zhangsan").build();System.out.println("主线程start==================");myTaskExecutor.execute(() -> {UserContext.setLoginUser(loginUser);try {testService.doSomething();} catch (Exception e) {e.printStackTrace();} finally {UserContext.remove();}});Thread.sleep(5000L);System.out.println("主线程end===================");}
}

测试示例

运行结果：

这种写法，每次写异步任务需要用户时，都要把用户信息set，remove。那么有没有一种写法可以让写业务代码时更加纯粹一点，让程序员更关注业务，代码更加美观呢？
其实，我们可以自定义Runnable加上自定义线程池来实现。

升级写法

• UserContextRunnable.java

public class UserContextRunnable implements Runnable {private final LoginUser currentUser;private final Runnable runnable;public UserContextRunnable(LoginUser currentUser, Runnable runnable) {this.currentUser = currentUser;this.runnable = runnable;}@Overridepublic void run() {try {UserContext.setLoginUser(currentUser);runnable.run();} finally {UserContext.remove();}}
}

• UserContextTaskExecutor.java

public class UserContextTaskExecutor extends ThreadPoolTaskExecutor {private static final long serialVersionUID = 7334165009514720624L;private LoginUser currentUser;public void user(LoginUser currentUser) {this.currentUser = currentUser;}public void execute(LoginUser currentUser, @NotNull Runnable task) {super.execute(new UserContextRunnable(currentUser, task));}public void execute(@NotNull Runnable task) {if (currentUser != null) {super.execute(new UserContextRunnable(currentUser, task));}else{super.execute(task);}}
}

测试示例

@SpringBootTest
public class UserAsyncTransmitTest {@Resourceprivate Executor userContextTaskExecutor;@Resourceprivate TestService testService;@Testvoid test() throws InterruptedException {LoginUser loginUser = LoginUser.builder().username("zhangsan").build();System.out.println("主线程start==================");userContextTaskExecutor.execute(new UserContextRunnable(loginUser, ()-> testService.doSomething()));Thread.sleep(5000L);System.out.println("主线程end===================");}
}

运行结果：