一、AsyncConfigurerSupport 简介
spring 中开启异步只要在配置类加上
@EnableAsync 同时在service方法中加上@Async即可，注意service中的方法想要异步调用必须是通过注入调用(spring 代理)。
@Service
public class ServiceA{
public void testA(){
testB();
}
@Async
public void testB(){
}
}
上述方法在调用testA时是同步调用，而非异步调用，方法内部的直接调用是没有经过spring 代理的。
二、自定义异步调用的线程池和异常处理
AsyncConfigurerSupport 只定义了两个方法分别用于自定义异步线程池、异步产生的异常捕获，通过实现此类即可实现自定义的异步线程池。
demo如下:
新建子类 AsyncConfigHandler
@Configuration
@EnableAsync
public class AsyncConfigHandler extends AsyncConfigurerSupport {
@Override
public Executor getAsyncExecutor() {
ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
executor.setCorePoolSize(5);
executor.setMaxPoolSize(10);
executor.setQueueCapacity(10);
executor.initialize();
return executor;
}
@Override
public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
return new MyAsyncUncaughtExceptionHandler();
}
@Bean // /actuator/shutdown
@Override
public Executor getAsyncExecutor2() {
ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
executor.setTaskDecorator(new SomeTaskDecorator());
executor.setCorePoolSize(4);
executor.setMaxPoolSize(8);
executor.setQueueCapacity(100);
executor.setAllowCoreThreadTimeOut(false);
executor.setKeepAliveSeconds(0);
executor.setThreadNamePrefix("DefaultAsync-");
executor.setWaitForTasksToCompleteOnShutdown(true); // 다 끝날때까지 대기
executor.initialize();
return executor;
}
static class SomeTaskDecorator implements TaskDecorator {
@Override
public Runnable decorate(Runnable runnable) {
return () -> {
try {
log.info("Some Task Decorator Start");
runnable.run();
} finally {
log.info("Some Task Decorator End");
}
};
}
}
}
class MyAsyncUncaughtExceptionHandler implements AsyncUncaughtExceptionHandler {
@Override
public void handleUncaughtException(Throwable ex, Method method, Object... params) {
System.out.println("class#method: " + method.getDeclaringClass().getName() + "#" + method.getName());
System.out.println("type : " + ex.getClass().getName());
System.out.println("exception : " + ex.getMessage());
}
}
编写支持异步调用注解@Async的 DemoService
@Service
public class DemoService {
@Async
public void testAsync() throws InterruptedException {
System.out.println("这里是异步方法");
TimeUnit.SECONDS.sleep(10);
int i = 1 / 0;
}
}
编写测试 controller
@RestController
@RequestMapping(value = "time")
public class DemoController {
@Autowired
private DemoService demoService;
@RequestMapping(value = "getTimeAndAsync")
public String getTimeAndAsync() throws InterruptedException {
demoService.testAsync();
return "异步加载=》" + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
}
}
新建spring boot应用的步骤省略
访问 http://localhost:8080/time/getTimeAndAsync
浏览器会立即输出
异步加载=》2021-02-20 15:56:16
等待十秒钟后会捕获异常
class#method: com.example.bootdemo.service.DemoService#testAsync
type : java.lang.ArithmeticException
exception : / by zero
同步调用中可以采用 @RestControllerAdvice 和 @ExceptionHandler 注解捕获全局的异常然后进行处理，如果是异步调用则需要实现 AsyncUncaughtExceptionHandler 进行单独的额外处理。
