(1). 项目结构如下
lixin-macbook:Workspace lixin$ tree shedlock-example
shedlock-example
├── pom.xml
├── src
│ ├── main
│ │ ├── java
│ │ │ └── help
│ │ │ └── lixin
│ │ │ └── samples
│ │ │ ├── ProviderApplication.java
│ │ │ ├── config
│ │ │ │ └── ShedLockConfig.java
│ │ │ ├── controller
│ │ │ │ └── HelloController.java
│ │ │ └── tasks
│ │ │ └── HelloWorldTask.java
│ │ └── resources
│ │ ├── application.properties
│ │ └── logback-spring.xml
│ └── test
│ ├── java
│ └── resources
└── target
(2). 添加依赖(pom.xml)
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>help.lixin</groupId>
<artifactId>shedlock-example</artifactId>
<packaging>jar</packaging>
<version>1.0.0</version>
<name>shedlock-example</name>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>8</maven.compiler.source>
<maven.compiler.target>8</maven.compiler.target>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Greenwich.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>2.1.0.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-netflix</artifactId>
<version>2.1.1.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- DataSource初始化(DataSourceConfiguration) -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.49</version>
</dependency>
<!-- 添加ShedLock依赖 -->
<dependency>
<groupId>net.javacrumbs.shedlock</groupId>
<artifactId>shedlock-spring</artifactId>
<version>4.23.1-SNAPSHOT</version>
</dependency>
<!-- 添加lock提供者 -->
<dependency>
<groupId>net.javacrumbs.shedlock</groupId>
<artifactId>shedlock-provider-jdbc-template</artifactId>
<version>4.23.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
</project>
(3). application.properties
server.port=8080
spring.application.name=shedlock-example
# 连接池类型
spring.datasource.type=com.zaxxer.hikari.HikariDataSource
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/shedlock?useSSL=false
(4). mysql创建数据库和表
mysql> create database shedlock;
Query OK, 1 row affected (0.02 sec)
mysql> use shedlock;
Database changed
mysql> CREATE TABLE shedlock(name VARCHAR(64) NOT NULL, lock_until TIMESTAMP(3) NOT NULL, locked_at TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3), locked_by VARCHAR(255) NOT NULL, PRIMARY KEY (name));
(5). ShedLockConfig
package help.lixin.samples.config;
import javax.sql.DataSource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.core.JdbcTemplate;
import net.javacrumbs.shedlock.core.LockProvider;
import net.javacrumbs.shedlock.provider.jdbctemplate.JdbcTemplateLockProvider;
@Configuration
public class ShedLockConfig {
// 配置锁的提供者
@Bean
public LockProvider lockProvider(@Autowired DataSource dataSource) {
return new JdbcTemplateLockProvider(
JdbcTemplateLockProvider.Configuration.builder()
.withJdbcTemplate(new JdbcTemplate(dataSource))
.build()
);
}
}
(6). HelloWorldTask
package help.lixin.samples.tasks;
import java.util.Date;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
import net.javacrumbs.shedlock.spring.annotation.SchedulerLock;
@Component
public class HelloWorldTask {
@Scheduled(cron = "*/5 * * * * ?")
// ***********************************************
// 定义锁的名称,最小锁住时间(lockAtLeastFor)和最大锁住时间(lockAtMostFor).
// ***********************************************
@SchedulerLock(name = "hello-world", lockAtLeastFor = "20000", lockAtMostFor = "30000")
public void helloworld() {
System.out.println(String.format("[%s] Hello World job run...", new Date()));
}
}
(7). ProviderApplication
package help.lixin.samples;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;
import net.javacrumbs.shedlock.spring.annotation.EnableSchedulerLock;
@SpringBootApplication
@EnableScheduling
// ***************************************************
// 注意:需要启用注解@EnableSchedulerLock
// ***************************************************
@EnableSchedulerLock(defaultLockAtMostFor = "120m")
public class ProviderApplication {
public static void main(String[] args) throws Exception {
SpringApplication.run(ProviderApplication.class, args);
}
}
(8). 运行查看控制台
# 1. 测试不添加分布式锁(不加注解@SchedulerLock)的情况下(每5秒会执行一次).
[Tue May 11 15:49:45 CST 2021] Hello World job run...
[Tue May 11 15:49:50 CST 2021] Hello World job run...
[Tue May 11 15:49:55 CST 2021] Hello World job run...
[Tue May 11 15:50:00 CST 2021] Hello World job run...
# 2. 测试添加分布锁(增加注解@SchedulerLock)的情况下
# 虽然,定时任务是每隔5秒执行一次,但是,分布式锁定义的是:每次任务要锁住20秒.
# 所以,定时任务加锁失败的情况下,是直接跳过的.
[Tue May 11 15:51:35 CST 2021] Hello World job run...
[Tue May 11 15:52:00 CST 2021] Hello World job run...
[Tue May 11 15:52:25 CST 2021] Hello World job run...
[Tue May 11 15:52:45 CST 2021] Hello World job run...
(9). 总结
有人肯定会想问:明明是个分布式锁,非要跟定时任务绑在一起,这个框架,能不能做到,不和定时任务绑定呢?
答案是:可以的,因为:shedlock-spring是对shedlock-core的二次封装,以适应于定时任务场景而已.后面的小节,我会对ShedLock源码剖析.
