Java 原生异步编程与Spring 异步编程 详解

简介

Java 异步编程是现代高性能应用开发的核心技术之一，它允许程序在执行耗时操作（如网络请求、文件 IO）时不必阻塞主线程，从而提高系统吞吐量和响应性。

异步 vs 同步

• 同步：任务按顺序执行，后续任务需等待前任务完成。

public String syncTask() {// 模拟耗时操作Thread.sleep(1000);return "Result";
}

• 异步：任务并行或在后台执行，主线程立即返回。

public CompletableFuture<String> asyncTask() {return CompletableFuture.supplyAsync(() -> {try {Thread.sleep(1000);} catch (InterruptedException e) {throw new RuntimeException(e);}return "Result";});
}

Java 原生异步支持

手动创建线程

最基本的异步方式是创建 Thread 或实现 Runnable。

• 缺点：管理线程池困难，资源浪费，难以复用，缺乏结果处理机制。

public class BasicAsync {public static void main(String[] args) {Thread thread = new Thread(() -> {try {Thread.sleep(1000);System.out.println("Task completed");} catch (InterruptedException e) {e.printStackTrace();}});thread.start();System.out.println("Main thread continues");}
}

使用 ExecutorService

• 优点：提供线程池管理，复用线程，减少创建开销

• 缺点：Future.get() 是阻塞的，难以链式调用

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;public class ThreadPoolExample {public static void main(String[] args) {ExecutorService executor = Executors.newFixedThreadPool(2);executor.submit(() -> {Thread.sleep(1000);System.out.println("Task 1 completed");});executor.submit(() -> {Thread.sleep(500);System.out.println("Task 2 completed");});executor.shutdown();}
}

常用方法：

• submit(Runnable)：提交无返回值的任务。

• submit(Callable)：提交有返回值的任务，返回 Future。

• shutdown()：关闭线程池，不接受新任务。

线程池类型：

• Executors.newFixedThreadPool(n)：固定大小线程池。

• Executors.newCachedThreadPool()：动态调整线程数。

• Executors.newSingleThreadExecutor()：单线程执行。

线程池类型对比：

类型	特性	适用场景
FixedThreadPool	固定线程数，无界队列	负载稳定的长期任务
CachedThreadPool	自动扩容，60秒闲置回收	短时突发任务
ScheduledThreadPool	支持定时/周期性任务	心跳检测、定时报表
WorkStealingPool	使用 ForkJoinPool，任务窃取算法	计算密集型并行任务

Future（Java 5+）

import java.util.concurrent.*;public class FutureExample {public static void main(String[] args) throws Exception {ExecutorService executor = Executors.newFixedThreadPool(1);Future<String> future = executor.submit(() -> {Thread.sleep(1000);return "Task completed";});// 主线程继续System.out.println("Doing other work");// 阻塞获取结果String result = future.get(); // 等待任务完成System.out.println(result);executor.shutdown();}
}

方法

• get()：阻塞获取结果。

• isDone()：检查任务是否完成。

• cancel(boolean)：取消任务。

缺点

• get() 是阻塞的，不利于非阻塞编程。

• 难以组合多个异步任务。

CompletableFuture（Java 8+）

支持链式调用，真正现代化异步编程方式。

import java.util.concurrent.CompletableFuture;public class CompletableFutureExample {public static void main(String[] args) {CompletableFuture.supplyAsync(() -> {try {Thread.sleep(1000);} catch (InterruptedException e) {throw new RuntimeException(e);}return "Task result";}).thenApply(result -> result.toUpperCase()) // 转换结果.thenAccept(result -> System.out.println(result)) // 消费结果.exceptionally(throwable -> {System.err.println("Error: " + throwable.getMessage());return null;});System.out.println("Main thread continues");}
}

虚拟线程（Java 21+，Project Loom）

虚拟线程是 Java 21 引入的轻量级线程，适合高并发 I/O 密集型任务。

public class VirtualThreadExample {public static void main(String[] args) {try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {executor.submit(() -> {try {Thread.sleep(1000);System.out.println("Task completed in virtual thread");} catch (InterruptedException e) {e.printStackTrace();}});}System.out.println("Main thread continues");}
}

优势

• 轻量级，创建开销极低（相比传统线程）。

• 适合 I/O 密集型任务（如 HTTP 请求、数据库查询）。

注意

• 不适合 CPU 密集型任务（可能导致线程饥饿）。

• Spring Boot 3.2+ 支持虚拟线程（需配置）。

阻塞 vs 非阻塞

类型	是否阻塞	获取结果方式
Future<T>	✅ 是	future.get()（阻塞）
CompletableFuture<T>	✅（get） ❌（then）	支持非阻塞链式处理
@Async + Future/CompletableFuture	✅	get() 或回调
WebFlux	❌ 完全非阻塞	响应式 Mono / Flux

Future<T> vs CompletableFuture<T>：核心对比

功能	Future<T>	CompletableFuture<T>
Java 版本	Java 5+	Java 8+
是否可组合	❌ 不支持	✅ 支持链式组合、并行执行
支持异步回调	❌ 无	✅ 有 .thenApply()、.thenAccept() 等
支持异常处理	❌ 无	✅ 有 .exceptionally() 等
可取消	✅ 支持 cancel()	✅ 也支持
阻塞获取	✅ get() 阻塞	✅ get() 阻塞（也可非阻塞）
使用场景	简单线程任务	多异步任务组合、复杂控制流

Spring 异步编程（基于 @Async）

配置类或启动类启用异步支持

@SpringBootApplication
@EnableAsync
public class Application {public static void main(String[] args) {SpringApplication.run(Application.class, args);}
}

@Configuration
@EnableAsync
public class AsyncConfig {
}

无返回值用法

// 无返回值的异步方法
@Async
public void sendEmail(String to) {System.out.println("异步发送邮件给: " + to);try { Thread.sleep(2000); } catch (InterruptedException e) {}System.out.println("邮件发送完成");
}

使用 Future<T>

创建异步方法

@Service
public class AsyncService {@Asyncpublic Future<String> processTask() {// 模拟耗时操作return new AsyncResult<>("Task completed");}
}

调用并获取结果：

@Autowired
private AsyncService asyncService;public void executeTask() throws Exception {Future<String> future = asyncService.processTask();String result = future.get(); // 阻塞等待结果
}

使用 CompletableFuture<T>

创建异步方法

@Async
public CompletableFuture<String> asyncMethod() {return CompletableFuture.completedFuture("Async Result");
}

调用方式：

CompletableFuture<String> result = asyncService.asyncMethod();
// 非阻塞，可以做其他事
String value = result.get(); // 阻塞获取

线程池配置

使用自定义配置类

@Configuration
public class AsyncConfig {@Bean("taskExecutor")public Executor taskExecutor() {ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();executor.setCorePoolSize(5);      // 核心线程数executor.setMaxPoolSize(20);      // 最大线程数executor.setQueueCapacity(100);   // 队列容量executor.setKeepAliveSeconds(30); // 空闲线程存活时间executor.setThreadNamePrefix("async-task-");executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());executor.initialize();return executor;}
}// 指定线程池
@Async("taskExecutor")
public Future<String> customPoolTask() { ... }

使用配置文件

# application.yml
spring:task:execution:pool:core-size: 5max-size: 20queue-capacity: 100thread-name-prefix: async-shutdown:await-termination: trueterminate-on-timeout: true

Spring WebFlux 示例

@Service
public class UserService {public Mono<String> getUser() {return Mono.just("用户信息").delayElement(Duration.ofSeconds(2));}public Flux<String> getAllUsers() {return Flux.just("用户1", "用户2", "用户3").delayElements(Duration.ofSeconds(1));}
}

@RestController
@RequestMapping("/users")
public class UserController {@Autowiredprivate UserService userService;@GetMapping("/one")public Mono<String> getUser() {return userService.getUser();}@GetMapping("/all")public Flux<String> getAllUsers() {return userService.getAllUsers();}
}

调用时非阻塞行为体现

• Mono<String> 表示未来异步返回一个值；

• Flux<String> 表示异步返回多个值；

• 请求立即返回 Publisher，只有订阅时才开始执行（懒执行、非阻塞）；

• 它不占用线程，不会“卡死线程”等待值返回。

SpringBoot 集成示例

• 标记 @Async 注解：

@Async 标记方法为异步执行，Spring 在线程池中运行该方法。

import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;@Service
public class AsyncService {@Asyncpublic CompletableFuture<String> doAsyncTask() {try {Thread.sleep(1000);} catch (InterruptedException e) {throw new RuntimeException(e);}return CompletableFuture.completedFuture("Task completed");}
}

• 启用异步

在主类或配置类上添加 @EnableAsync。

@SpringBootApplication
@EnableAsync
public class Application {public static void main(String[] args) {SpringApplication.run(Application.class, args);}
}

• 控制器调用异步方法

@RestController
public class AsyncController {@Autowiredprivate AsyncService asyncService;@GetMapping("/async")public String triggerAsync() {asyncService.doAsyncTask().thenAccept(result -> System.out.println(result));return "Task triggered";}
}

• 自定义线程池

Spring 默认使用 SimpleAsyncTaskExecutor，不适合生产环境。推荐配置自定义线程池。

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;@Configuration
public class AsyncConfig {@Bean(name = "taskExecutor")public ThreadPoolTaskExecutor taskExecutor() {ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();executor.setCorePoolSize(2);executor.setMaxPoolSize(10);executor.setQueueCapacity(25);executor.setThreadNamePrefix("AsyncThread-");executor.initialize();return executor;}
}

• 指定线程池：

@Async("taskExecutor")
public CompletableFuture<String> doAsyncTask() {// 异步逻辑
}

• 为 @Async 方法定义全局异常处理器

@Component
public class AsyncExceptionHandler implements AsyncUncaughtExceptionHandler {@Overridepublic void handleUncaughtException(Throwable ex, Method method, Object... params) {System.err.println("Async error: " + ex.getMessage());}
}

• Spring Boot 测试：

@SpringBootTest
public class AsyncServiceTest {@Autowiredprivate AsyncService asyncService;@Testvoid testAsync() throws Exception {CompletableFuture<String> future = asyncService.doAsyncTask();assertEquals("Task completed", future.get(2, TimeUnit.SECONDS));}
}

并行调用多个服务示例

并行调用 getUser 和 getProfile，总耗时接近较慢的任务（~1s）。

@Service
public class UserService {@Asyncpublic CompletableFuture<User> getUser(Long id) {return CompletableFuture.supplyAsync(() -> {// 模拟远程调用try {Thread.sleep(1000);} catch (InterruptedException e) {throw new RuntimeException(e);}return new User(id, "User" + id);});}@Asyncpublic CompletableFuture<Profile> getProfile(Long id) {return CompletableFuture.supplyAsync(() -> {try {Thread.sleep(500);} catch (InterruptedException e) {throw new RuntimeException(e);}return new Profile(id, "Profile" + id);});}
}@RestController
public class UserController {@Autowiredprivate UserService userService;@GetMapping("/user/{id}")public CompletableFuture<UserProfile> getUserProfile(@PathVariable Long id) {return userService.getUser(id).thenCombine(userService.getProfile(id),(user, profile) -> new UserProfile(user, profile));}
}

异步批量处理示例

并行处理 10 个任务，显著减少总耗时。

@Service
public class BatchService {@Asyncpublic CompletableFuture<Void> processItem(int item) {return CompletableFuture.runAsync(() -> {try {Thread.sleep(100);System.out.println("Processed item: " + item);} catch (InterruptedException e) {throw new RuntimeException(e);}});}
}@RestController
public class BatchController {@Autowiredprivate BatchService batchService;@PostMapping("/batch")public CompletableFuture<Void> processBatch() {List<CompletableFuture<Void>> futures = new ArrayList<>();for (int i = 1; i <= 10; i++) {futures.add(batchService.processItem(i));}return CompletableFuture.allOf(futures.toArray(new CompletableFuture[0]));}
}

响应式 WebFlux 示例

@Service
public class ReactiveService {public Mono<String> fetchData() {return Mono.just("Data").delayElement(Duration.ofSeconds(1));}
}@RestController
public class ReactiveController {@Autowiredprivate ReactiveService reactiveService;@GetMapping("/data")public Mono<String> getData() {return reactiveService.fetchData();}
}

Spring Data JPA 集成示例

JPA 默认阻塞操作，可通过 @Async 包装异步调用。

@Repository
public interface UserRepository extends JpaRepository<User, Long> {}@Service
public class UserService {@Autowiredprivate UserRepository userRepository;@Asyncpublic CompletableFuture<User> findUser(Long id) {return CompletableFuture.supplyAsync(() -> userRepository.findById(id).orElse(null));}
}

MyBatis Plus 集成示例

MyBatis Plus 默认阻塞，可通过 @Async 或线程池异步化。

@Mapper
public interface UserMapper extends BaseMapper<User> {}@Service
public class UserService {@Autowiredprivate UserMapper userMapper;@Asyncpublic CompletableFuture<User> getUser(Long id) {return CompletableFuture.supplyAsync(() -> userMapper.selectById(id));}
}

注意事项

• @Async 方法必须是 public 的。

• 不能在同一类内调用 @Async 方法（因 Spring AOP 代理机制）。

• 默认线程池由 Spring 提供，可自定义。

CompletableFuture 所有核心 API

• supplyAsync()：异步执行任务，返回值

• runAsync()：异步执行任务，无返回值

• thenApply()：接收前面任务结果并返回新结果

• thenAccept()：接收结果但无返回

• thenRun()：不接收结果也不返回，仅执行

• thenCompose()：嵌套异步任务

• thenCombine()：两个任务都完成后，合并结果

• allOf()：等多个任务全部完成

• anyOf()：任一任务完成即继续

• exceptionally()：捕获异常并处理

• whenComplete()：无论成功失败都执行

• handle()：可处理正常或异常结果

CompletableFuture<T> 用法详解

创建异步任务

supplyAsync：基本异步任务执行

CompletableFuture<String> cf = CompletableFuture.supplyAsync(() -> "Result");

runAsync：异步执行任务，无返回值

CompletableFuture<Void> cf = CompletableFuture.runAsync(() -> System.out.println("Async run"));

任务转换

thenApply(Function)：转换结果，对结果加工

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> "data").thenApply(data -> data.toUpperCase());System.out.println(future.get()); // DATA

thenCompose(Function)：扁平化链式异步

CompletableFuture<String> composed = CompletableFuture.supplyAsync(() -> "A").thenCompose(a -> CompletableFuture.supplyAsync(() -> a + "B"));composed.thenAccept(System.out::println); // 输出 AB

thenCombine(CompletionStage, BiFunction)：两个任务完成后合并结果

CompletableFuture<String> cf1 = CompletableFuture.supplyAsync(() -> "Hello");
CompletableFuture<String> cf2 = CompletableFuture.supplyAsync(() -> "World");cf1.thenCombine(cf2, (a, b) -> a + " " + b).thenAccept(System.out::println);

CompletableFuture<String> f1 = CompletableFuture.supplyAsync(() -> "A");
CompletableFuture<String> f2 = CompletableFuture.supplyAsync(() -> "B");CompletableFuture<String> result = f1.thenCombine(f2, (a, b) -> a + b);
System.out.println(result.get()); // AB

消费结果

thenAccept(Consumer)：消费结果

CompletableFuture.supplyAsync(() -> "Result").thenAccept(result -> System.out.println("Received: " + result));

thenRun(Runnable)：继续执行下一个任务，无需前面结果

CompletableFuture.supplyAsync(() -> "X").thenRun(() -> System.out.println("Next step executed"));

异常处理

exceptionally(Function<Throwable, T>)：异常处理

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {if (true) throw new RuntimeException("Oops!");return "ok";
}).exceptionally(ex -> "Fallback: " + ex.getMessage());System.out.println(future.get());

handle(BiFunction<T, Throwable, R>)：同时处理正常与异常结果

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {throw new RuntimeException("Error!");
}).handle((result, ex) -> {if (ex != null) return "Handled: " + ex.getMessage();return result;
});System.out.println(future.get());

whenComplete(BiConsumer<T, Throwable>)：类似 finally

• 在 CompletableFuture 执行完毕后执行一个回调，无论是成功还是异常。

• 不会改变原来的结果或异常，仅用于处理副作用（如日志）。

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> "Final Result").whenComplete((result, ex) -> {System.out.println("Completed with: " + result);});

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {if (true) throw new RuntimeException("出错了");return "成功";
}).whenComplete((result, exception) -> {if (exception != null) {System.out.println("发生异常：" + exception.getMessage());} else {System.out.println("执行结果：" + result);}
});

并发组合

allOf / anyOf：组合任务

CompletableFuture<Void> all = CompletableFuture.allOf(task1, task2);
CompletableFuture<Object> any = CompletableFuture.anyOf(task1, task2);

allOf(…)：等待全部任务完成

需要单独从每个任务中再 .get() 拿到结果

CompletableFuture<String> f1 = CompletableFuture.supplyAsync(() -> "A");
CompletableFuture<String> f2 = CompletableFuture.supplyAsync(() -> "B");CompletableFuture<Void> all = CompletableFuture.allOf(f1, f2);
all.thenRun(() -> System.out.println("All done")).get();

CompletableFuture<String> userFuture = CompletableFuture.supplyAsync(() -> fetchUser());
CompletableFuture<String> orderFuture = CompletableFuture.supplyAsync(() -> fetchOrder());// 两个任务都完成后执行
CompletableFuture<Void> bothDone = CompletableFuture.allOf(userFuture, orderFuture);bothDone.thenRun(() -> {try {String user = userFuture.get();String order = orderFuture.get();System.out.println("用户: " + user + ", 订单: " + order);} catch (Exception e) {e.printStackTrace();}
});

anyOf(…)：任一完成即触发

CompletableFuture<String> f1 = CompletableFuture.supplyAsync(() -> {try { Thread.sleep(1000); } catch (InterruptedException e) {}return "fast";
});
CompletableFuture<String> f2 = CompletableFuture.supplyAsync(() -> "slow");CompletableFuture<Object> any = CompletableFuture.anyOf(f1, f2);
System.out.println(any.get()); // 输出最快那个

超时控制

orTimeout(long timeout, TimeUnit unit)：超时异常

如果在指定时间内没有完成，就抛出 TimeoutException 异常。

CompletableFuture<String> f = CompletableFuture.supplyAsync(() -> {try { Thread.sleep(2000); } catch (Exception e) {}return "late result";
}).orTimeout(1, TimeUnit.SECONDS);try {System.out.println(f.get());
} catch (Exception e) {System.out.println("Timeout: " + e.getMessage());
}

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {try {Thread.sleep(3000);} catch (InterruptedException e) {e.printStackTrace();}return "执行完成";
}).orTimeout(2, TimeUnit.SECONDS).exceptionally(ex -> "捕获到异常：" + ex.getClass().getSimpleName());System.out.println("结果：" + future.join()); // 打印“捕获到异常：TimeoutException”

completeOnTimeout(T value, long timeout, TimeUnit unit)：超时默认值

如果在指定时间内没有完成，则返回一个默认值，并完成该任务。

CompletableFuture<String> f = CompletableFuture.supplyAsync(() -> {try { Thread.sleep(2000); } catch (Exception e) {}return "slow";
}).completeOnTimeout("timeout default", 1, TimeUnit.SECONDS);System.out.println(f.get()); // timeout default

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {try {Thread.sleep(3000); // 模拟耗时任务} catch (InterruptedException e) {e.printStackTrace();}return "正常返回结果";
}).completeOnTimeout("超时默认值", 2, TimeUnit.SECONDS);System.out.println("最终结果：" + future.join()); // 会打印“超时默认值”

自定义线程池

ExecutorService pool = Executors.newFixedThreadPool(2);CompletableFuture<String> f = CompletableFuture.supplyAsync(() -> "pooled", pool);
System.out.println(f.get());
pool.shutdown();

异步任务 + 消费结果

CompletableFuture<Void> future = CompletableFuture.supplyAsync(() -> "hello").thenAccept(result -> System.out.println("结果是：" + result));

异步任务 + 转换结果（链式调用）

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> "5").thenApply(Integer::parseInt).thenApply(num -> num * 2).thenApply(Object::toString);

异常处理

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {if (true) throw new RuntimeException("出错了！");return "success";}).exceptionally(ex -> {System.out.println("异常: " + ex.getMessage());return "默认值";});

多任务并发组合（allOf / anyOf）

CompletableFuture<String> f1 = CompletableFuture.supplyAsync(() -> "A");
CompletableFuture<String> f2 = CompletableFuture.supplyAsync(() -> "B");// 等待全部完成
CompletableFuture<Void> all = CompletableFuture.allOf(f1, f2);
all.join();System.out.println("结果：" + f1.join() + ", " + f2.join());

合并两个任务结果

CompletableFuture<Integer> f1 = CompletableFuture.supplyAsync(() -> 100);
CompletableFuture<Integer> f2 = CompletableFuture.supplyAsync(() -> 200);CompletableFuture<Integer> result = f1.thenCombine(f2, Integer::sum);
System.out.println(result.get()); // 输出 300

自定义线程池

ExecutorService pool = Executors.newFixedThreadPool(4);CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {return "线程池中的任务";
}, pool);System.out.println(future.get());
pool.shutdown();

链式异步处理

CompletableFuture.supplyAsync(() -> "Step 1").thenApply(s -> s + " -> Step 2").thenCompose(s -> CompletableFuture.supplyAsync(() -> s + " -> Step 3")).thenAccept(System.out::println).exceptionally(ex -> {ex.printStackTrace();return null;});

订单处理示例

public class OrderSystem {@Async("dbExecutor")public CompletableFuture<Order> saveOrder(Order order) {// 数据库写入操作return CompletableFuture.completedFuture(order);}@Async("httpExecutor")public CompletableFuture<String> notifyLogistics(Order order) {// 调用物流APIreturn CompletableFuture.completedFuture("SUCCESS");}public void processOrder(Order order) {CompletableFuture<Order> saveFuture = saveOrder(order);saveFuture.thenCompose(savedOrder -> notifyLogistics(savedOrder)).exceptionally(ex -> {log.error("物流通知失败", ex);return "FALLBACK";});}
}

总结图谱

CompletableFuture
├─ 创建任务
│  ├─ runAsync() -> 无返回值
│  └─ supplyAsync() -> 有返回值
├─ 处理结果
│  ├─ thenApply() -> 转换
│  ├─ thenAccept() -> 消费
│  ├─ thenRun() -> 执行新任务
│  ├─ thenCombine() -> 合并结果
│  └─ thenCompose() -> 链式调用
├─ 异常处理
│  ├─ exceptionally()
│  ├─ handle()
│  └─ whenComplete()
├─ 组合任务
│  ├─ allOf()
│  └─ anyOf()
└─ 超时控制├─ orTimeout()└─ completeOnTimeout()

什么场景适合用 Java 异步（@Async / CompletableFuture）？

场景	是否适合异步？
调用多个远程服务并行	✅ 很适合
复杂 CPU 运算耗时任务	✅ 可以放到异步线程池
简单业务逻辑、数据库操作	❌ 不建议，同步更可控
非主流程的日志、打点操作	✅ 合适异步处理

Java 和 .NET 异步处理对比

并行调用两个服务，提高响应速度

Spring Boot 示例（@Async + CompletableFuture）

项目结构

└── src└── main├── java│   ├── demo│   │   ├── controller│   │   │   └── AggregateController.java│   │   ├── service│   │   │   ├── RemoteService.java│   │   │   └── RemoteServiceImpl.java│   │   └── DemoApplication.java

RemoteService.java

public interface RemoteService {@AsyncCompletableFuture<String> getUserInfo();@AsyncCompletableFuture<String> getAccountInfo();
}

RemoteServiceImpl.java

@Service
public class RemoteServiceImpl implements RemoteService {@Overridepublic CompletableFuture<String> getUserInfo() {try {Thread.sleep(2000); // 模拟耗时} catch (InterruptedException e) {throw new RuntimeException(e);}return CompletableFuture.completedFuture("UserInfo");}@Overridepublic CompletableFuture<String> getAccountInfo() {try {Thread.sleep(3000); // 模拟耗时} catch (InterruptedException e) {throw new RuntimeException(e);}return CompletableFuture.completedFuture("AccountInfo");}
}

AggregateController.java

@RestController
@RequestMapping("/api")
public class AggregateController {@Autowiredprivate RemoteService remoteService;@GetMapping("/aggregate")public ResponseEntity<String> aggregate() throws Exception {CompletableFuture<String> userFuture = remoteService.getUserInfo();CompletableFuture<String> accountFuture = remoteService.getAccountInfo();// 等待所有完成CompletableFuture.allOf(userFuture, accountFuture).join();// 获取结果String result = userFuture.get() + " + " + accountFuture.get();return ResponseEntity.ok(result);}
}

DemoApplication.java

@SpringBootApplication
@EnableAsync
public class DemoApplication {public static void main(String[] args) {SpringApplication.run(DemoApplication.class, args);}
}

.NET 示例（async/await）

项目结构

└── Controllers└── AggregateController.cs
└── Services└── IRemoteService.cs└── RemoteService.cs

IRemoteService.cs

public interface IRemoteService {Task<string> GetUserInfoAsync();Task<string> GetAccountInfoAsync();
}

RemoteService.cs

public class RemoteService : IRemoteService {public async Task<string> GetUserInfoAsync() {await Task.Delay(2000); // 模拟耗时return "UserInfo";}public async Task<string> GetAccountInfoAsync() {await Task.Delay(3000); // 模拟耗时return "AccountInfo";}
}

AggregateController.cs

[ApiController]
[Route("api/[controller]")]
public class AggregateController : ControllerBase {private readonly IRemoteService _remoteService;public AggregateController(IRemoteService remoteService) {_remoteService = remoteService;}[HttpGet("aggregate")]public async Task<IActionResult> Aggregate() {var userTask = _remoteService.GetUserInfoAsync();var accountTask = _remoteService.GetAccountInfoAsync();await Task.WhenAll(userTask, accountTask);var result = $"{userTask.Result} + {accountTask.Result}";return Ok(result);}
}

Java vs .NET 异步用法对比总结

方面	Java（Spring Boot）	.NET Core（ASP.NET）
异步声明方式	@Async + CompletableFuture	async/await
返回值类型	CompletableFuture<T>	Task<T>
等待多个任务	CompletableFuture.allOf()	Task.WhenAll()
是否阻塞	.get() 会阻塞，链式不阻塞	await 非阻塞
简洁性	稍复杂（需要注解和线程池配置）	极简、天然异步支持