1. Spring Boot使用@Async實現異步調用
鏈接:#link
原文：http://blog.csdn.net/a286352250/article/details/53157822
項目GitHub地址 ：
https://github.com/FrameReserve/TrainingBoot
Spring Boot（十）使用@Async實現異步調用 ，標記地址：
https://github.com/FrameReserve/TrainingBoot/releases/tag/0.0.10
1.1. Spring Boot啓動類，增加@EnableAsync註解配置：
src/main/java/com/training/SpringBootServlet.java
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package com.training;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.support.SpringBootServletInitializer;
import org.springframework.scheduling.annotation.EnableAsync;
@SpringBootApplication
@EnableAsync
public class SpringBootServlet extends SpringBootServletInitializer {
// jar啓動
public static void main(String[] args) {
SpringApplication.run(SpringBootServlet.class, args);
}
// tomcat war啓動
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(SpringBootServlet.class);
}
}
1.2. 測試：
增加異步方法Service，線程休眠：
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package com.training.async.service.impl;
import java.util.Random;
import java.util.concurrent.Future;
import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.AsyncResult;
import org.springframework.stereotype.Service;
import com.training.async.service.DemoAsyncService;
@Service
public class DemoAsyncServiceImpl implements DemoAsyncService {
public static Random random =new Random();
@Async
public Future<String> doTaskOne() throws Exception {
System.out.println("開始做任務一");
long start = System.currentTimeMillis();
Thread.sleep(random.nextInt(10000));
long end = System.currentTimeMillis();
System.out.println("完成任務一，耗時：" + (end - start) + "毫秒");
return new AsyncResult<>("任務一完成");
}
@Async
public Future<String> doTaskTwo() throws Exception {
System.out.println("開始做任務二");
long start = System.currentTimeMillis();
Thread.sleep(random.nextInt(10000));
long end = System.currentTimeMillis();
System.out.println("完成任務二，耗時：" + (end - start) + "毫秒");
return new AsyncResult<>("任務二完成");
}
@Async
public Future<String> doTaskThree() throws Exception {
System.out.println("開始做任務三");
long start = System.currentTimeMillis();
Thread.sleep(random.nextInt(10000));
long end = System.currentTimeMillis();
System.out.println("完成任務三，耗時：" + (end - start) + "毫秒");
return new AsyncResult<>("任務三完成");
}
}
1.3. 調用異步測試測試，查看控制檯輸出執行順序：
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package com.training.async.controller;
import io.swagger.annotations.ApiOperation;
import java.util.concurrent.Future;
import javax.annotation.Resource;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import com.training.async.service.DemoAsyncService;
import com.training.core.dto.ResultDataDto;
@RestController
@RequestMapping(value="/async")
public class DemoAsyncController {
@Resource
private DemoAsyncService demoAsyncService;
/**
* 測試異步方法調用順序
*/
@ApiOperation(value="測試異步方法調用順序", notes="getEntityById")
@RequestMapping(value = "/getTestDemoAsync", method = RequestMethod.GET)
public @ResponseBody ResultDataDto getEntityById() throws Exception {
long start = System.currentTimeMillis();
Future<String> task1 = demoAsyncService.doTaskOne();
Future<String> task2 = demoAsyncService.doTaskTwo();
Future<String> task3 = demoAsyncService.doTaskThree();
while(true) {
if(task1.isDone() && task2.isDone() && task3.isDone()) {
// 三個任務都調用完成，退出循環等待
break;
}
Thread.sleep(1000);
}
long end = System.currentTimeMillis();
System.out.println("任務全部完成，總耗時：" + (end - start) + "毫秒");
return ResultDataDto.addSuccess();
}
}
原文：http://blog.csdn.net/v2sking/article/details/72795742
1.4. 什麼是異步調用？
異步調用是相對於同步調用而言的，同步調用是指程序按預定順序一步步執行，每一步必須等到上一步執行完後才能執行，異步調用則無需等待上一步程序執行完即可執行。
1.5. 如何實現異步調用？
多線程，這是很多人第一眼想到的關鍵詞，沒錯，多線程就是一種實現異步調用的方式。
在非spring目項目中我們要實現異步調用的就是使用多線程方式，可以自己實現Runable接口或者集成Thread類，或者使用jdk1.5以上提供了的Executors線程池。
1.6. StrngBoot中則提供了很方便的方式執行異步調用。
按照官方示例開擼
代碼入下
1.6.1. maven依賴：
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<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.3.RELEASE</version>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
1.6.2. 啓動類：添加@EnableAsync註解
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@SpringBootApplication
@EnableAsync
public class Application{
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
1.6.3. Controller
只需在需要異步執行方法上添加@Async註解
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@RestController
@RequestMapping("")
public class AsyncTaskController {
@RequestMapping("")
public String doTask() throws InterruptedException{
long currentTimeMillis = System.currentTimeMillis();
this.task1();
this.task2();
this.task3();
long currentTimeMillis1 = System.currentTimeMillis();
return "task任務總耗時:"+(currentTimeMillis1-currentTimeMillis)+"ms";
}
@Async
public void task1() throws InterruptedException{
long currentTimeMillis = System.currentTimeMillis();
Thread.sleep(1000);
long currentTimeMillis1 = System.currentTimeMillis();
System.out.println("task1任務耗時:"+(currentTimeMillis1-currentTimeMillis)+"ms");
}
@Async
public void task2() throws InterruptedException{
long currentTimeMillis = System.currentTimeMillis();
Thread.sleep(2000);
long currentTimeMillis1 = System.currentTimeMillis();
System.out.println("task2任務耗時:"+(currentTimeMillis1-currentTimeMillis)+"ms");
}
@Async
public void task3() throws InterruptedException{
long currentTimeMillis = System.currentTimeMillis();
Thread.sleep(3000);
long currentTimeMillis1 = System.currentTimeMillis();
System.out.println("task3任務耗時:"+(currentTimeMillis1-currentTimeMillis)+"ms");
}
}
1.6.4. main函數運行spirngboot項目，啓動完成後瀏覽器訪問：
1.6.5. 控制檯：
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task1任務耗時:1012ms
task2任務耗時:2009ms
task3任務耗時:3004ms
等了一段瀏覽器時候輸出入下：
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task任務總耗時:6002ms
1.6.5.1. 異步並沒有執行！
難道是代碼寫錯了？反覆檢查了好幾遍，並沒有發現什麼明顯錯誤，想起spring對@Transactional註解時也有類似問題，spring掃描時具有@Transactional註解方法的類時，是生成一個代理類，由代理類去開啓關閉事務，而在同一個類中，方法調用是在類體內執行的，spring無法截獲這個方法調用。
1.6.5.2. 豁然開朗，將異步任務單獨放到一個類中，調整代碼入下：
1.6.6. Controller
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@RequestMapping("")
@RestController
public class AsyncTaskController {
@Autowired
private AsyncTask asyncTask;
@RequestMapping("")
public String doTask() throws InterruptedException{
long currentTimeMillis = System.currentTimeMillis();
asyncTask.task1();
asyncTask.task2();
asyncTask.task3();
long currentTimeMillis1 = System.currentTimeMillis();
return "task任務總耗時:"+(currentTimeMillis1-currentTimeMillis)+"ms";
}
}
1.6.7. 異步任務類
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@Component
public class AsyncTask {
@Async
public void task1() throws InterruptedException{
long currentTimeMillis = System.currentTimeMillis();
Thread.sleep(1000);
long currentTimeMillis1 = System.currentTimeMillis();
System.out.println("task1任務耗時:"+(currentTimeMillis1-currentTimeMillis)+"ms");
}
@Async
public void task2() throws InterruptedException{
long currentTimeMillis = System.currentTimeMillis();
Thread.sleep(2000);
long currentTimeMillis1 = System.currentTimeMillis();
System.out.println("task2任務耗時:"+(currentTimeMillis1-currentTimeMillis)+"ms");
}
@Async
public void task3() throws InterruptedException{
long currentTimeMillis = System.currentTimeMillis();
Thread.sleep(3000);
long currentTimeMillis1 = System.currentTimeMillis();
System.out.println("task3任務耗時:"+(currentTimeMillis1-currentTimeMillis)+"ms");
}
}
1.6.8. 控制檯：
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task1任務耗時:1012ms
task2任務耗時:2009ms
task3任務耗時:3004ms
訪問瀏覽器結果入下：
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task任務總耗時:19ms
1.6.9. 異步調用成功！
1.7. 如何知道三個異步任務什麼時候執行完，執行的結果怎樣呢？可以採用添加Fature回調方式判斷
代碼入下：
1.7.1. 異步任務類
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@Component
public class AsyncTask {
@Async
public Future<String> task1() throws InterruptedException{
long currentTimeMillis = System.currentTimeMillis();
Thread.sleep(1000);
long currentTimeMillis1 = System.currentTimeMillis();
System.out.println("task1任務耗時:"+(currentTimeMillis1-currentTimeMillis)+"ms");
return new AsyncResult<String>("task1執行完畢");
}
@Async
public Future<String> task2() throws InterruptedException{
long currentTimeMillis = System.currentTimeMillis();
Thread.sleep(2000);
long currentTimeMillis1 = System.currentTimeMillis();
System.out.println("task2任務耗時:"+(currentTimeMillis1-currentTimeMillis)+"ms");
return new AsyncResult<String>("task2執行完畢");
}
@Async
public Future<String> task3() throws InterruptedException{
long currentTimeMillis = System.currentTimeMillis();
Thread.sleep(3000);
long currentTimeMillis1 = System.currentTimeMillis();
System.out.println("task3任務耗時:"+(currentTimeMillis1-currentTimeMillis)+"ms");
return new AsyncResult<String>("task3執行完畢");
}
}
1.7.2. Controller
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@RequestMapping("")
@RestController
public class AsyncTaskController {
@Autowired
private AsyncTask asyncTask;
@RequestMapping("")
public String doTask() throws InterruptedException{
long currentTimeMillis = System.currentTimeMillis();
Future<String> task1 = asyncTask.task1();
Future<String> task2 = asyncTask.task2();
Future<String> task3 = asyncTask.task3();
String result = null;
for (;;) {
if(task1.isDone() && task2.isDone() && task3.isDone()) {
// 三個任務都調用完成，退出循環等待
break;
}
Thread.sleep(1000);
}
long currentTimeMillis1 = System.currentTimeMillis();
result = "task任務總耗時:"+(currentTimeMillis1-currentTimeMillis)+"ms";
return result;
}
}
1.7.3. 控制檯輸出：
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task1任務耗時:1000ms
task2任務耗時:2001ms
task3任務耗時:3001ms
1.7.4. 瀏覽器輸出：
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task任務總耗時:4015ms