SpringBoot 2.x （11）：定时任务与异步任务

定时任务：有时候我们需要做定时的一些操作，比如统计信息，定时发送邮件等

在SpringBoot中如何进行整合和使用呢？

有哪些方式可以实现定时任务呢？

Java自带的java.util.timer：

优点：Java自带，无需导包

缺点：配置复杂，时间延后等问题

Quartz框架：

优点：配置简单，使用方便

缺点：需要导包

@EnableSchedule：

优点：SpringBoot自带，高兼容，无需导包

使用：

在启动类加入@EnableScheduling注解

package org.dreamtech.demo;

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

@SpringBootApplication
@EnableScheduling
public class DemoApplication {

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

}

定义Task：

package org.dreamtech.demo.task;

import java.util.Date;

import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

@Component
public class TestTask {
    @Scheduled(fixedRate = 2000)
    public void test() {
        System.out.println("[ " + "当前时间 : " + new Date() + " ]");
    }
}

效果：控制台每过两秒打印一次当前时间

[ 当前时间 : Fri May 10 14:01:42 CST 2019 ]
[ 当前时间 : Fri May 10 14:01:44 CST 2019 ]
[ 当前时间 : Fri May 10 14:01:46 CST 2019 ]
[ 当前时间 : Fri May 10 14:01:48 CST 2019 ]
[ 当前时间 : Fri May 10 14:01:50 CST 2019 ]
[ 当前时间 : Fri May 10 14:01:52 CST 2019 ]
[ 当前时间 : Fri May 10 14:01:54 CST 2019 ]

使用CRON表达式：

每两秒执行一次的另一种表达方式：

    @Scheduled(cron = "*/2 * * * * *")

关于CRON表达式的百度即可，一堆介绍，我就不多写了

异步任务：适用于发送短信、邮件、处理Log等问题

为什么需要异步任务？

比如电商网站用户下单，要做的事情有这几样：库存查询、用户校验、余额校验等

SpringBoot使用异步任务：@EnableAsync注解

基本实现：

启动类加入@EnableAsync注解

package org.dreamtech.demo;

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

@SpringBootApplication
@EnableAsync
public class DemoApplication {

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

}

定义任务类：这里模拟耗时的操作

package org.dreamtech.demo.task;

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

@Component
@Async
public class AsyncTask {
    public void test1() throws InterruptedException {
        long begin = System.currentTimeMillis();
        Thread.sleep(1000);
        long end = System.currentTimeMillis();
        System.out.println("[ " + "任务1耗时 : " + (end - begin) + " ]");
    }

    public void test2() throws InterruptedException {
        long begin = System.currentTimeMillis();
        Thread.sleep(2000);
        long end = System.currentTimeMillis();
        System.out.println("[ " + "任务2耗时 : " + (end - begin) + " ]");
    }

    public void test3() throws InterruptedException {
        long begin = System.currentTimeMillis();
        Thread.sleep(3000);
        long end = System.currentTimeMillis();
        System.out.println("[ " + "任务2耗时 : " + (end - begin) + " ]");
    }
}

Controller层做测试：

package org.dreamtech.demo.controller;

import org.dreamtech.demo.task.AsyncTask;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TestController {
    @Autowired
    private AsyncTask task;

    @GetMapping("/test")
    private Object test() {
        long begin = System.currentTimeMillis();
        try {
            task.test1();
            task.test2();
            task.test3();
        } catch (Exception e) {
            e.printStackTrace();
        }
        long end = System.currentTimeMillis();
        System.out.println("[ " + "Controller耗时 : " + (end - begin) + " ]");
        return "test";
    }
}

访问localhost:8080/test打印如下：

[ Controller耗时 : 4 ]
[ 任务1耗时 : 1000 ]
[ 任务2耗时 : 2000 ]
[ 任务2耗时 : 3000 ]

结论：异步任务的执行类似多线程，可以用来做一些耗时操作

有时候需要某个任务确定执行完毕才能继续其他操作

如何获取任务的执行结果呢？

package org.dreamtech.demo.task;

import java.util.concurrent.Future;

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

@Component
@Async
public class AsyncTask {

    public Future<String> test1() throws InterruptedException {
        long begin = System.currentTimeMillis();
        Thread.sleep(1000);
        long end = System.currentTimeMillis();
        System.out.println("[ " + "任务1耗时 : " + (end - begin) + " ]");
        return new AsyncResult<String>("任务1");
    }

    public Future<String> test2() throws InterruptedException {
        long begin = System.currentTimeMillis();
        Thread.sleep(2000);
        long end = System.currentTimeMillis();
        System.out.println("[ " + "任务2耗时 : " + (end - begin) + " ]");
        return new AsyncResult<String>("任务2");
    }

    public Future<String> test3() throws InterruptedException {
        long begin = System.currentTimeMillis();
        Thread.sleep(3000);
        long end = System.currentTimeMillis();
        System.out.println("[ " + "任务3耗时 : " + (end - begin) + " ]");
        return new AsyncResult<String>("任务3");
    }
}

Controller：

package org.dreamtech.demo.controller;

import java.util.concurrent.Future;

import org.dreamtech.demo.task.AsyncTask;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TestController {
    @Autowired
    private AsyncTask task;

    @GetMapping("/test")
    private Object test() {
        long begin = System.currentTimeMillis();
        try {
            Future<String> task1Result = task.test1();
            Future<String> task2Result = task.test2();
            Future<String> task3Result = task.test3();
            while (true) {
                if (task1Result.isDone() && task2Result.isDone() && task3Result.isDone()) {
                    break;
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        long end = System.currentTimeMillis();
        System.out.println("[ " + "Controller耗时 : " + (end - begin) + " ]");
        return "test";
    }
}

访问localhost:8080/test

等待3秒之后，打印如下：

[ 任务1耗时 : 1001 ]
[ 任务2耗时 : 2001 ]
[ 任务3耗时 : 3001 ]
[ Controller耗时 : 3007 ]

只有三个任务都完成，Controller层代码才会执行完毕

总结：异步任务大大地提高了开发的效率

顺便来记录Logback的使用：

Logback：一款优秀的日志框架

SpringBoot的Starter默认日志框架：Logback，默认级别：INFO

如果我们想以DEBUG方式启动：java -jar springboot.jar --debug

配置文件：官方推荐名称logback-spring.xml

<?xml version="1.0" encoding="UTF-8" ?>
<configuration>

    <appender name="consoleApp"
        class="ch.qos.logback.core.ConsoleAppender">
        <layout class="ch.qos.logback.classic.PatternLayout">
            <pattern>
                %date{yyyy-MM-dd HH:mm:ss.SSS} %-5level[%thread]%logger{56}.%method:%L -%msg%n
            </pattern>
        </layout>
    </appender>

    <appender name="fileInfoApp"
        class="ch.qos.logback.core.rolling.RollingFileAppender">
        <filter class="ch.qos.logback.classic.filter.LevelFilter">
            <level>ERROR</level>
            <onMatch>DENY</onMatch>
            <onMismatch>ACCEPT</onMismatch>
        </filter>
        <encoder>
            <pattern>
                %date{yyyy-MM-dd HH:mm:ss.SSS} %-5level[%thread]%logger{56}.%method:%L -%msg%n
            </pattern>
        </encoder>
        <!-- 滚动策略 -->
        <rollingPolicy
            class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <!-- 路径 -->
            <fileNamePattern>app_log/log/app.info.%d.log</fileNamePattern>
        </rollingPolicy>
    </appender>

    <appender name="fileErrorApp"
        class="ch.qos.logback.core.rolling.RollingFileAppender">
        <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
            <level>ERROR</level>
        </filter>
        <encoder>
            <pattern>
                %date{yyyy-MM-dd HH:mm:ss.SSS} %-5level[%thread]%logger{56}.%method:%L -%msg%n
            </pattern>
        </encoder>
        <!-- 设置滚动策略 -->
        <rollingPolicy
            class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <!-- 路径 -->
            <fileNamePattern>app_log/log/app.err.%d.log</fileNamePattern>
            <!-- 控制保留的归档文件的最大数量，超出数量就删除旧文件，假设设置每个月滚动， 且<maxHistory> 是1，则只保存最近1个月的文件，删除之前的旧文件 -->
            <MaxHistory>1</MaxHistory>
        </rollingPolicy>
    </appender>
    <root level="INFO">
        <appender-ref ref="consoleApp" />
        <appender-ref ref="fileInfoApp" />
        <appender-ref ref="fileErrorApp" />
    </root>
</configuration>

使用和测试：

package org.dreamtech.demo.controller;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TestController {

    private Logger logger = LoggerFactory.getLogger(this.getClass());

    @GetMapping("/log")
    private Object log() {
        logger.debug("test");
        logger.info("test");
        logger.warn("test");
        logger.error("test");
        return "log";
    }
}

访问localhost:8080/log

会在项目目录生成一个新目录app_log

存在两个文件：一个用来存放ERROR级别信息，一个存放INFO级别和WARN级别

2019-05-11 12:53:53.668 ERROR[http-nio-8080-exec-1]org.dreamtech.demo.controller.TestController.log:18 -test

2019-05-11 12:53:36.264 INFO [main]org.dreamtech.demo.DemoApplication.logStarting:50 -Starting DemoApplication on DESKTOP-59O94TD with PID 14180 (D:\PROJECT\STS_PROJECT\demo\target\classes started by 20235 in D:\PROJECT\STS_PROJECT\demo)
2019-05-11 12:53:36.266 INFO [main]org.dreamtech.demo.DemoApplication.logStartupProfileInfo:675 -No active profile set, falling back to default profiles: default
2019-05-11 12:53:37.019 INFO [main]o.s.boot.web.embedded.tomcat.TomcatWebServer.initialize:90 -Tomcat initialized with port(s): 8080 (http)
2019-05-11 12:53:37.031 INFO [main]org.apache.coyote.http11.Http11NioProtocol.log:173 -Initializing ProtocolHandler ["http-nio-8080"]
2019-05-11 12:53:37.039 INFO [main]org.apache.catalina.core.StandardService.log:173 -Starting service [Tomcat]
2019-05-11 12:53:37.041 INFO [main]org.apache.catalina.core.StandardEngine.log:173 -Starting Servlet engine: [Apache Tomcat/9.0.17]
2019-05-11 12:53:37.122 INFO [main]o.a.catalina.core.ContainerBase.[Tomcat].[localhost].[/].log:173 -Initializing Spring embedded WebApplicationContext
2019-05-11 12:53:37.122 INFO [main]org.springframework.web.context.ContextLoader.prepareWebApplicationContext:296 -Root WebApplicationContext: initialization completed in 824 ms
2019-05-11 12:53:37.289 INFO [main]o.s.scheduling.concurrent.ThreadPoolTaskExecutor.initialize:171 -Initializing ExecutorService 'applicationTaskExecutor'
2019-05-11 12:53:37.413 INFO [main]org.apache.coyote.http11.Http11NioProtocol.log:173 -Starting ProtocolHandler ["http-nio-8080"]
2019-05-11 12:53:37.447 INFO [main]o.s.boot.web.embedded.tomcat.TomcatWebServer.start:204 -Tomcat started on port(s): 8080 (http) with context path ''
2019-05-11 12:53:37.450 INFO [main]org.dreamtech.demo.DemoApplication.logStarted:59 -Started DemoApplication in 1.528 seconds (JVM running for 2.39)
2019-05-11 12:53:53.641 INFO [http-nio-8080-exec-1]o.a.catalina.core.ContainerBase.[Tomcat].[localhost].[/].log:173 -Initializing Spring DispatcherServlet 'dispatcherServlet'
2019-05-11 12:53:53.642 INFO [http-nio-8080-exec-1]org.springframework.web.servlet.DispatcherServlet.initServletBean:524 -Initializing Servlet 'dispatcherServlet'
2019-05-11 12:53:53.650 INFO [http-nio-8080-exec-1]org.springframework.web.servlet.DispatcherServlet.initServletBean:546 -Completed initialization in 8 ms
2019-05-11 12:53:53.668 INFO [http-nio-8080-exec-1]org.dreamtech.demo.controller.TestController.log:16 -test
2019-05-11 12:53:53.668 WARN [http-nio-8080-exec-1]org.dreamtech.demo.controller.TestController.log:17 -test
2019-05-11 12:54:23.513 INFO [RMI TCP Connection(2)-127.0.0.1]o.s.b.a.SpringApplicationAdminMXBeanRegistrar$SpringApplicationAdmin.shutdown:163 -Application shutdown requested.
2019-05-11 12:54:23.515 INFO [RMI TCP Connection(2)-127.0.0.1]o.s.scheduling.concurrent.ThreadPoolTaskExecutor.shutdown:208 -Shutting down ExecutorService 'applicationTaskExecutor'