Spring任務執行器(TaskExecutor)

Spring任務執行器(TaskExecutor)
    Spring通州任務執行器(TaskExecutor)來實現多線程和並發編程，使用ThreadPoolTaskExecutor
可實現一個基於線程的TaskExecutor，而實際開發中任務一般是非阻塞的，即異步的，所以我們要在配置類中
通過@EnableAsync開啟對異步任務的支持，並通過在實際執行的Bean的方法中使用@Async注解來聲明其是一個異步任務。

實例

1.配置類

package com.wisely.highlight_spring4.ch3.taskexecutor;

import java.util.concurrent.Executor;

import org.springframework.aop.interceptor.AsyncUncaughtExceptionHandler;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.AsyncConfigurer;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
@Configuration
@ComponentScan("com.wisely.highlight_spring4.ch3.taskexecutor")
@EnableAsync //1 
public class TaskExecutorConfig implements AsyncConfigurer{//2

 @Override
 public Executor getAsyncExecutor() {//2
 ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
 taskExecutor.setCorePoolSize(5);
 taskExecutor.setMaxPoolSize(10);
 taskExecutor.setQueueCapacity(25);
 taskExecutor.initialize();
 return taskExecutor;
 }

 @Override
 public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
 return null;
 }
}


代碼解釋
1.利用@EnableAsync注解開啟異步任務支持。
2.配置類實現AsyncConfigurer接口並重寫getAsyncExecutor方法，並返回一個ThreadPoolTaskExecutor，這樣我們就獲得了已個基於線程池TaskExecutor.

任務執行類

package com.wisely.highlight_spring4.ch3.taskexecutor;

import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;
@Service
public class AsyncTaskService {
 
 @Async //1
 public void executeAsyncTask(Integer i){
 System.out.println("執行異步任務 "+i);
 }

 @Async
 public void executeAsyncTaskPlus(Integer i){
 System.out.println("執行異步任務+1"+(i+1));
 }
}


代碼解釋
1.通過@Async注解表明該方法是個異步方法，如果注解在類級別，則表明該類所以的方法都是異步的，
而這里的方法自動被注入使用ThreadPoolTaskExecutor作為TaskExecutor。

運行

package com.wisely.highlight_spring4.ch3.taskexecutor;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Main {
 
 public static void main(String[] args) {
 AnnotationConfigApplicationContext context =
 new AnnotationConfigApplicationContext(TaskExecutorConfig.class);
 
 AsyncTaskService asyncTaskService = context.getBean(AsyncTaskService.class);
 
 for(int i =0 ;i<10;i++){
 asyncTaskService.executeAsyncTask(i);
 asyncTaskService.executeAsyncTaskPlus(i);
 }
 context.close();
 }
}

結果是並發執行而不是順序執行的。