Spring Boot 2 -自定义启动运行逻辑

我们有时候会遇到这种需求，项目启动后立马执行一些逻辑。比如缓存预热，或者上线后的广播之类等等。

CommandLineRunner 接口
package org.springframework.boot;

import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;

/**

• Interface used to indicate that a bean should run when it is contained within
• a {@link SpringApplication}. Multiple {@link CommandLineRunner} beans can be defined
• within the same application context and can be ordered using the {@link Ordered}
• interface or {@link Order @Order} annotation.
• If you need access to {@link ApplicationArguments} instead of the raw String array
• consider using {@link ApplicationRunner}.
• @author Dave Syer
• @see ApplicationRunner
  */
  @FunctionalInterface
  public interface CommandLineRunner {

/**

• Callback used to run the bean.
• @param args incoming main method arguments
• @throws Exception on error
  */
  void run(String… args) throws Exception;

}

CommandLineRunner 作用是当springApplication 启动后，在同一应用上下文中定义的多个 CommandLineRunner 类型的 Spring Bean 按照标记顺序执行。如果你想替代以数组方式接收 args 参数 可以用 另一个接口代替 org.springframework.boot.ApplicationRunner 。

talk is cheap show your code 下面我就来操作一波演示一下。

优先级比较高的 CommandLineRunner 实现

package cn.felord.begin;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.CommandLineRunner;
import org.springframework.core.Ordered;
import org.springframework.stereotype.Component;

/**

• 优先级比较高 通过实现接口{@link Ordered}的方式 来指定优先级
• 命令行测试参数 --foo=bar --dev.name=码农小胖哥 java,springboot
• @author Felordcn
• @since 2019/6/17 23:06
  */
  @Slf4j
  @Component
  public class HighOrderCommandLineRunner implements CommandLineRunner , Ordered {
  @Override
  public void run(String… args) throws Exception {

log.info(“i am highOrderRunner”);
}

@Override
public int getOrder() {
return Ordered.HIGHEST_PRECEDENCE;
}
}

优先级比较低的 CommandLineRunner 实现

package cn.felord.begin;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.CommandLineRunner;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

/**

• 优先级比较低 通过注解{@link Order}方式来指定优先级
• 比最优大64 说明会在 {@link HighOrderCommandLineRunner} 之后执行
• @author Felord
• @since 2019/6/17 23:07
  */
  @Slf4j
  @Order(Ordered.HIGHEST_PRECEDENCE + 64)
  @Component
  public class LowOrderCommandLineRunner implements CommandLineRunner {
  @Override
  public void run(String… args) throws Exception {
  log.info(“i am lowOrderRunner”);
  }
  }

用 ApplicationRunner 实现最低优先级
package cn.felord.begin;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.core.Ordered;
import org.springframework.stereotype.Component;
import org.springframework.util.CollectionUtils;

import java.util.List;

/**

• 优先级最低的实现
• @author Felordcn
• @since 2019/6/18 22:13
  */
  @Slf4j
  @Component
  public class DefaultApplicationRunner implements ApplicationRunner, Ordered {
  @Override
  public void run(ApplicationArguments args) throws Exception {

log.info(“i am applicationRunner”);

}

@Override
public int getOrder() {
return Ordered.HIGHEST_PRECEDENCE+65;
}
}

启动springboot 后控制台打印出了执行结果

2019-11-02 21:18:14.603 INFO 10244 — [ main] c.f.begin.HighOrderCommandLineRunner : i am highOrderRunner
2019-11-02 21:18:14.604 INFO 10244 — [ main] c.f.begin.LowOrderCommandLineRunner : i am lowOrderRunner
2019-11-02 21:18:14.604 INFO 10244 — [ main] c.f.begin.DefaultApplicationRunner : i am applicationRunner