Springboot实战系列之@Async

先看一个@Async的demo

一、demo

1，开启异步任务的开关

在启动类上添加注解@EnableAsync

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2，编写controller类

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;

@RestController
public class TestAsyncController {

    @Autowired
    private TestAsyncService asyncService;

    @RequestMapping(value = "/test/async", method = RequestMethod.GET)
    @ResponseBody
    public String testAsync() {
        long start = System.currentTimeMillis();
        Future<String> asyncTaskRes1 = asyncService.asyncTask1();
        Future<String> asyncTaskRes2 = asyncService.asyncTask2();
        Future<String> asyncTaskRes3 = asyncService.asyncTask3();
        String str1 = "";
        String str2 = "";
        String str3 = "";
        try {
            str1 = asyncTaskRes1.get();
            str2 = asyncTaskRes2.get();
            str3 = asyncTaskRes3.get();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
        // System.out.println(str1 + str2 + str3);
        long end = System.currentTimeMillis();
        long time = end - start;
        return String.valueOf(time);
    }
}

3, service类

@Async注解控制方法是否为异步的

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

import java.util.concurrent.Future;

@Service
public class TestAsyncService {


    @Async
    public Future<String> asyncTask1(){
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        String value = "asyncTask1";
        // 注意返回
        return new AsyncResult(value);
    }

    // @Async
    public Future<String> asyncTask2(){
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        String value = "asyncTask2";
        return new AsyncResult(value);
    }

    // @Async
    public Future<String> asyncTask3(){
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        String value = "asyncTask3";
        return new AsyncResult(value);
    }
    
}

结论

本来如果不加@Async，每个方法需要花5秒，一共就是15s; 如果都加上@Async注解就在5-6s的时间（应该有线程调度的消耗）。