1. 開啟非同步任務

package com.pibigstar;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableAsync;

@SpringBootApplication
@EnableAsync //開啟非同步任務
public class SpringbootDemoApplication
 
 {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootDemoApplication.class, args);
    }
}

2. 編寫非同步任務

package com.pibigstar.task;

import java.util.concurrent.Future;

import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.AsyncResult;
import
 
 org.springframework.stereotype.Component;

@Component
public class AsyncTask {

    @Async //非同步方法註解
    public Future<Boolean> task1() throws InterruptedException {
        long start = System.currentTimeMillis();
        Thread.sleep(1000);
        long end = System.currentTimeMillis();
        System.out.println("=====任務1 耗時："
 
+(end-start)+"======");
        //返回true，告訴此任務已完成
        return new AsyncResult<Boolean>(true);
    }

    @Async //非同步方法註解
    public Future<Boolean> task2() throws InterruptedException {
        long start = System.currentTimeMillis();
        Thread.sleep(800);
        long end = System.currentTimeMillis();
        System.out.println("=====任務2 耗時："+(end-start)+"======");
        //返回true，告訴此任務已完成
        return new AsyncResult<Boolean>(true);
    }

    @Async //非同步方法註解
    public Future<Boolean> task3() throws InterruptedException {
        long start = System.currentTimeMillis();
        Thread.sleep(600);
        long end = System.currentTimeMillis();
        System.out.println("=====任務3 耗時："+(end-start)+"======");
        //返回true，告訴此任務已完成
        return new AsyncResult<Boolean>(true);
    }
}

3. 啟動非同步任務

package com.pibigstar.web;

import java.util.concurrent.Future;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.pibigstar.task.AsyncTask;

@RestController
@RequestMapping("/task")
public class AsyncTaskController {

    @Autowired
    private AsyncTask asyncTask;

    @GetMapping("test")
    public String test() throws InterruptedException {
        long start = System.currentTimeMillis();
        Future<Boolean> a = asyncTask.task1();
        Future<Boolean> b = asyncTask.task2();
        Future<Boolean> c = asyncTask.task3();

        //迴圈到三個任務全部完成
        while (!a.isDone()||!b.isDone()||!c.isDone()) {
            if (a.isDone()&&b.isDone()&&c.isDone()) {
                break;
            }
        }
        long end = System.currentTimeMillis();
        String result = "任務完成，一共用時為："+(end-start)+"毫秒";
        System.out.println(result);
        return result;  
    }
}

4. 執行結果

任務1 睡眠了 1000毫秒，任務2 睡眠了800毫秒，任務3 睡眠了600毫秒，如果是同步執行的話三個任務完成應該是2400毫秒，而這裡只使用了1005毫秒，說明我們的任務執行確實是非同步執行

5. 非同步執行使用場景