多线程
Spring 通过任务执行器（TaskExecutor）来实现多线程和并发编程。使用ThreadPoolTaskExecutor可实现一个基于线程池的TaskExecutor。而实际开发中任务一般是非阻碍的，即异步的，所以我们要在配置类中通过@EnableAsync开启对异步的支持，并通过在实际执行的Bean的方法中使用@Async注解来声明其是一个异步任务。
示例
首先配置类
package com.cn.sola.config;
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.cn.sola.service")
@EnableAsync//利用此注解开启异步任务支持
public class TaskExecutorConfig implements AsyncConfigurer{
@Override
public Executor getAsyncExecutor() {
//配置类实现AsyncConfigurer 接口 并重写getAsyncExecutor方法并返回一个ThreadPoolTaskExecutor
//这样我们就获得了一个基于线程池的TaskExecutor
ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
taskExecutor.setCorePoolSize(5);
taskExecutor.setMaxPoolSize(10);
taskExecutor.setQueueCapacity(25);
taskExecutor.initialize();
return taskExecutor;
}
@Override
public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
// TODO Auto-generated method stub
return null;
}
}
任务执行类
package com.cn.sola.service;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;
@Service
public class AsyncTaskService {
@Async//该注表明该方法是个异步方法，如果注解在类级别，则表名该类所有的方法都是异步方
//而这里的方法自动被注入使用ThreadPoolTaskExecutor作为TaskExecutor
public void excuteAsyncTask(Integer i){
System.out.println("执行异步任务"+i);
}
@Async
public void excuteAsyncTaskPlus(Integer i){
System.out.println("执行异步任务+1:"+(i+1));
}
}
运行
package com.cn.sola;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.test.context.junit4.SpringRunner;
import com.cn.sola.config.TaskExecutorConfig;
import com.cn.sola.service.AsyncTaskService;
@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringBootShiZhanApplicationTests {
@Test
public void contextLoads() {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(TaskExecutorConfig.class);
AsyncTaskService bean = context.getBean(AsyncTaskService.class);
for(int i = 0 ; i<10 ; i++){
bean.excuteAsyncTask(i);
bean.excuteAsyncTaskPlus(i);
}
context.close();
}
}
结果是这样的，结果是并非执行而不是顺序执行的
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.0.3.RELEASE)
2018-07-09 10:57:36.981 INFO 8160 --- [ main] c.c.s.SpringBootShiZhanApplicationTests : Starting SpringBootShiZhanApplicationTests on DESKTOP-LN7MO04 with PID 8160 (started by JAVA in D:\SpringBootWorkSpace\SpringBootShiZhan)
2018-07-09 10:57:36.982 INFO 8160 --- [ main] c.c.s.SpringBootShiZhanApplicationTests : No active profile set, falling back to default profiles: default
2018-07-09 10:57:37.665 INFO 8160 --- [ main] trationDelegate$BeanPostProcessorChecker : Bean 'taskExecutorConfig' of type [com.cn.sola.config.TaskExecutorConfig$$EnhancerBySpringCGLIB$$b7273a85] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2018-07-09 10:57:37.669 INFO 8160 --- [ main] o.s.s.concurrent.ThreadPoolTaskExecutor : Initializing ExecutorService
2018-07-09 10:57:38.664 INFO 8160 --- [ main] c.c.s.SpringBootShiZhanApplicationTests : Started SpringBootShiZhanApplicationTests in 1.93 seconds (JVM running for 2.616)
2018-07-09 10:57:38.756 INFO 8160 --- [ main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@27aae97b: startup date [Mon Jul 09 10:57:38 CST 2018]; root of context hierarchy
2018-07-09 10:57:38.792 INFO 8160 --- [ main] trationDelegate$BeanPostProcessorChecker : Bean 'taskExecutorConfig' of type [com.cn.sola.config.TaskExecutorConfig$$EnhancerBySpringCGLIB$$b7273a85] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2018-07-09 10:57:38.792 INFO 8160 --- [ main] o.s.s.concurrent.ThreadPoolTaskExecutor : Initializing ExecutorService
2018-07-09 10:57:38.810 INFO 8160 --- [ main] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@27aae97b: startup date [Mon Jul 09 10:57:38 CST 2018]; root of context hierarchy
执行异步任务2
执行异步任务+1:3
执行异步任务3
执行异步任务+1:1
执行异步任务4
执行异步任务1
执行异步任务5
执行异步任务+1:6
执行异步任务6
执行异步任务+1:7
执行异步任务7
执行异步任务+1:8
执行异步任务8
执行异步任务+1:9
执行异步任务9
执行异步任务+1:10
执行异步任务0
执行异步任务+1:2
执行异步任务+1:5
执行异步任务+1:4计划任务
从Spring3.1开始，计划任务在Spring中的实现变得异常的简单。首先通过在配置配注解@EnableScheduling来开启对任务的支持，然后再要执行计划任务的方法上声明注解@Scheduled，声明这是一个计划任务。
这段很简单配置好声明个注解就可以了
package com.cn.sola.service;
import java.text.SimpleDateFormat;
import java.util.Date;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Service;
@Service
public class ScheduledTaskService {
private static final SimpleDateFormat deteformat = new SimpleDateFormat("HH:mm:ss");
@Scheduled(fixedRate = 5000)//通过此注解声明该方法是计划任务，使用fixedRate属性每隔固定时间执行
public void reportCurrentTime(){
System.out.println("每五秒执行一次" + deteformat.format(new Date()));
}
@Scheduled(cron = "0 28 11 ? * *") //使用cron属性可以按照指定时间执行，本例指的是每天11点28分执行;cron是unix和类unix(Linux)系统下的定时任务
public void fixTimeExecution(){
System.out.println("在指定时间" + deteformat.format(new Date()) + "执行");
}
}配置类
package com.cn.sola.config;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableScheduling;
@Configuration
@ComponentScan("com.cn.sola.service")
@EnableScheduling//声明此注解对计划任务的支持
public class TaskSchedulerConfig{
}
直接运行即可，那么注解上的方法就会按照注解的时间执行
---------------------------------------------------------------------------------------------------------------------------
条件注解@Conditional
在之前学到，通过活动的profile，我们可以获得不同的Bean，Spring4提供了一个更通用的基于条件的Bean的创建，即使用@Conditional注解。
@Conditional根据满足某一个特定条件创建一个特定的Bean。比方说，当某个jar包在一个类路径下的时候，自动配置一个或多个Bean；或者只有某个Bean被创建才会创建另外一个Bean。总的来说，就是根据特定条件来控制Bean的创建行为，这样我们可以进行一些自动配置。
在SpringBoot中将会大量应用到条件注解，下面的示例将以不用的操作系统作为条件，我们将通过实现Condition接口并重写其Matches方法来构造判断条件，若在Windows系统下运行程序，则输出列表命令为dir；若在linux操作系统下运行程序，则输出列表命令为ls。
首先判断条件定义
windows
package com.cn.sola.bean;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.type.AnnotatedTypeMetadata;
public class WindowsCondition implements Condition{
@Override
public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
return context.getEnvironment().getProperty("os.name").contains("Windows");
}
}linux
package com.cn.sola.bean;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.type.AnnotatedTypeMetadata;
public class LinuxCondition implements Condition{
@Override
public boolean matches(ConditionContext context, AnnotatedTypeMetadata metdata) {
return context.getEnvironment().getProperty("os.name").contains("Linux");
}
}
不同系统下的Bean类
接口
package com.cn.sola.service;
public interface ListService {
public String showListCmd();
}
windows下所要创建的Bean的类
package com.cn.sola.service;
public class WindowListService implements ListService{
@Override
public String showListCmd() {
// TODO Auto-generated method stub
return "dir";
}
}
linux下要创建的bean类
package com.cn.sola.service;
public class LinuxService implements ListService{
@Override
public String showListCmd() {
// TODO Auto-generated method stub
return "ls";
}
}
配置类
package com.cn.sola.config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
import com.cn.sola.bean.LinuxCondition;
import com.cn.sola.bean.WindowsCondition;
import com.cn.sola.service.LinuxService;
import com.cn.sola.service.ListService;
import com.cn.sola.service.WindowListService;
@Configuration
public class ConditionConfig{
@Bean
@Conditional(WindowsCondition.class)//通过注解，符合windows条件则实例化下面的service
public ListService windowListService(){
return new WindowListService();
}
@Bean
@Conditional(LinuxCondition.class)//通过注解，符合linux条件则实例化下面的service
public ListService LinuxListService(){
return new LinuxService();
}
}
运行类
package com.cn.sola;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.test.context.junit4.SpringRunner;
import com.cn.sola.config.ConditionConfig;
import com.cn.sola.service.LinuxService;
import com.cn.sola.service.ListService;
@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringBootShiZhanApplicationTests {
@Test
public void contextLoads() {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(ConditionConfig.class);
ListService listservice = context.getBean(ListService.class);
System.out.println(context.getEnvironment().getProperty("os.name")+"系统下的列表命令为:" + listservice.showListCmd());
context.close();
}
}
结果
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.0.3.RELEASE)
2018-07-09 14:54:21.686 INFO 14104 --- [ main] c.c.s.SpringBootShiZhanApplicationTests : Starting SpringBootShiZhanApplicationTests on DESKTOP-LN7MO04 with PID 14104 (started by JAVA in D:\SpringBootWorkSpace\SpringBootShiZhan)
2018-07-09 14:54:21.687 INFO 14104 --- [ main] c.c.s.SpringBootShiZhanApplicationTests : No active profile set, falling back to default profiles: default
2018-07-09 14:54:23.480 INFO 14104 --- [ main] c.c.s.SpringBootShiZhanApplicationTests : Started SpringBootShiZhanApplicationTests in 2.049 seconds (JVM running for 2.786)
2018-07-09 14:54:23.607 INFO 14104 --- [ main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@67a056f1: startup date [Mon Jul 09 14:54:23 CST 2018]; root of context hierarchy
Windows 10系统下的列表命令为:dir
2018-07-09 14:54:23.633 INFO 14104 --- [ main] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@67a056f1: startup date [Mon Jul 09 14:54:23 CST 2018]; root of context hierarchy