1、@Async是SpringBoot自带的一个执行步任务注解
@EnableAsync // 开启异步
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
2、同步执行
定义几个方法，模拟耗时的操作
@Service
@Slf4j
public class ServiceDemoSync {
public void taskOne() throws Exception {
long start = System.currentTimeMillis();
Thread.sleep(200);
long end = System.currentTimeMillis();
System.out.println("线程：" + Thread.currentThread().getName() + "任务1执行结束,总耗时={" + (end - start) + "} 毫秒");
}
public void taskTwo() throws Exception {
long start = System.currentTimeMillis();
Thread.sleep(200);
long end = System.currentTimeMillis();
System.out.println("线程：" + Thread.currentThread().getName() + "任务2执行结束,总耗时={" + (end - start) + "} 毫秒");
}
public void taskThere() throws Exception {
long start = System.currentTimeMillis();
Thread.sleep(200);
long end = System.currentTimeMillis();
System.out.println("线程：" + Thread.currentThread().getName() + "任务3执行结束,总耗时={" + (end - start) + "} 毫秒");
}
}
测试一下
/**
* @author qbb
*/
@SpringBootTest
public class ServiceTestSync {
@Autowired
private ServiceDemoSync serviceDemoSync;
@Test
public void test01() throws Exception {
long start = System.currentTimeMillis();
serviceDemoSync.taskOne();
serviceDemoSync.taskTwo();
serviceDemoSync.taskThere();
Thread.sleep(200);
long end = System.currentTimeMillis();
System.out.println("总任务执行结束,总耗时={" + (end - start) + "} 毫秒");
}
}
3、异步执行
@Service
@Slf4j
public class ServiceDemo {
@Async
public void taskOne() throws Exception {
long start = System.currentTimeMillis();
Thread.sleep(200);
long end = System.currentTimeMillis();
System.out.println("线程：" + Thread.currentThread().getName() + "任务1执行结束,总耗时={" + (end - start) + "} 毫秒");
}
@Async
public void taskTwo() throws Exception {
long start = System.currentTimeMillis();
Thread.sleep(200);
long end = System.currentTimeMillis();
System.out.println("线程：" + Thread.currentThread().getName() + "任务2执行结束,总耗时={" + (end - start) + "} 毫秒");
}
@Async
public void taskThere() throws Exception {
long start = System.currentTimeMillis();
Thread.sleep(200);
long end = System.currentTimeMillis();
System.out.println("线程：" + Thread.currentThread().getName() + "任务3执行结束,总耗时={" + (end - start) + "} 毫秒");
}
}
@SpringBootTest
public class ServiceTest {
@Autowired
private ServiceDemo serviceDemo;
@Test
public void test01() throws Exception {
long start = System.currentTimeMillis();
serviceDemo.taskOne();
serviceDemo.taskTwo();
serviceDemo.taskThere();
Thread.sleep(200);
long end = System.currentTimeMillis();
System.out.println("总任务执行结束,总耗时={" + (end - start) + "} 毫秒");
}
}
4、使用自定义线程池
package com.qbb.service;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
import java.util.concurrent.Executor;
import java.util.concurrent.ThreadPoolExecutor;
/**
* 自定义线程池
*/
@Configuration
public class ExecutorAsyncConfig {
@Bean(name = "newAsyncExecutor")
public Executor newAsync() {
ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
// 设置核心线程数
taskExecutor.setCorePoolSize(2);
// 线程池维护线程的最大数量，只有在缓冲队列满了以后才会申请超过核心线程数的线程
taskExecutor.setMaxPoolSize(10);
// 缓存队列
taskExecutor.setQueueCapacity(2);
// 允许的空闲时间，当超过了核心线程数之外的线程在空闲时间到达之后会被销毁
taskExecutor.setKeepAliveSeconds(10);
// 异步方法内部线程名称
taskExecutor.setThreadNamePrefix("QIUQIU&LL-AsyncExecutor-");
// 拒绝策略
taskExecutor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
taskExecutor.initialize();
return taskExecutor;
}
}
定义线程任务
@Component
@Slf4j
public class FutureTaskExecutor {
@Async(value = "newAsyncExecutor")
public Future<String> taskOne() {
return new AsyncResult<>(Thread.currentThread().getName() + "one 完成");
}
@Async(value = "newAsyncExecutor")
public Future<String> taskTwo() {
return new AsyncResult<>(Thread.currentThread().getName() + "two 完成");
}
@Async
public Future<String> taskThree() {
return new AsyncResult<>(Thread.currentThread().getName() + "three 完成");
}
}
测试一下
/**
* @author qbb
*/
@SpringBootTest
@Slf4j
public class FutureTaskTestExecutor {
@Autowired
private FutureTaskExecutor futureTaskExecutor;
@Test
public void runAsync() throws Exception {
long start = System.currentTimeMillis();
Future<String> taskOne = futureTaskExecutor.taskOne();
Future<String> taskTwo = futureTaskExecutor.taskTwo();
Future<String> taskThere = futureTaskExecutor.taskThree();
while (true) {
if (taskOne.isDone() && taskTwo.isDone() && taskThere.isDone()) {
System.out.println("任务1返回结果={" + (taskOne.get()) + "},任务2返回结果={" + (taskTwo.get()) + "},任务3返回结果={" + (taskThere.get()) + "}");
break;
}
}
long end = System.currentTimeMillis();
System.out.println("总任务执行结束,总耗时={" + (end - start) + "} 毫秒");
}
}
注意点：不生效的情况
1、@Async作用在static修饰的方法上不生效
2、调用异步任务的方法和异步方法在同一个类时不生效
@Service
@Slf4j
public class ServiceDemo {
@Async
public void taskOne() throws Exception {
long start = System.currentTimeMillis();
Thread.sleep(200);
long end = System.currentTimeMillis();
System.out.println("线程：" + Thread.currentThread().getName() + "任务1执行结束,总耗时={" + (end - start) + "} 毫秒");
}
@Async
public void taskTwo() throws Exception {
long start = System.currentTimeMillis();
Thread.sleep(200);
long end = System.currentTimeMillis();
System.out.println("线程：" + Thread.currentThread().getName() + "任务2执行结束,总耗时={" + (end - start) + "} 毫秒");
}
@Async
public void taskThere() throws Exception {
long start = System.currentTimeMillis();
Thread.sleep(200);
long end = System.currentTimeMillis();
System.out.println("线程：" + Thread.currentThread().getName() + "任务3执行结束,总耗时={" + (end - start) + "} 毫秒");
}
@Test
public void test01() throws Exception {
long start = System.currentTimeMillis();
taskOne();
taskTwo();
taskThere();
Thread.sleep(200);
long end = System.currentTimeMillis();
System.out.println("总任务执行结束,总耗时={" + (end - start) + "} 毫秒");
}
}
