springboot 控制台输出调试

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控制台输出调试

为了方便测试，在启动springboot项目后，期望通过控制台输出，查看运行。
此时可以通过让**@SpringBootApplication类implements CommandLineRunner或者ApplicationRunner**接口，并实现run方法。

CommandLineRunner

CommandLineRunner接口的run方法会传递SpringApplication.run()方法中的字符数组参数args。

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@SpringBootApplication
public class Main implements CommandLineRunner {

    public static void main(String[] args) {
        System.out.println("main before run");
        SpringApplication.run(Main.class, "param1");
        System.out.println("main after run");
    }

    public void run(String... args) throws Exception {
        System.out.println("args[0]: " + args[0]);
        System.out.println("CommandLineRunner.run()");
    }

}

如果有多个@SpringBootApplication注解类且均实现了CommandLineRunner接口，可以通过**@Order注解指定run方法的执行顺序，或者通过实现Ordered接口的getOrder()**方法。
qQ320491

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package crick.wang.springbootstudy;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;

@SpringBootApplication
@Order(2)
public class Main implements CommandLineRunner {

    public static void main(String[] args) {
        System.out.println("main before run");
        SpringApplication.run(Main.class, "param1");
        System.out.println("main after run");
    }


    public void run(String... args) throws Exception {
        System.out.println("first args[0]: " + args[0]);
        System.out.println("first CommandLineRunner.run()");
    }

}

@SpringBootApplication
@Order(1)
class SecondMain implements CommandLineRunner {

    public void run(String... args) throws Exception {
        System.out.println("second args[0]: " + args[0]);
        System.out.println("second CommandLineRunner.run()");
    }

}

@SpringBootApplication
class ThirdMain implements CommandLineRunner, Ordered {

    public void run(String... args) throws Exception {
        System.out.println("third args[0]: " + args[0]);
        System.out.println("third CommandLineRunner.run()");
    }

    public int getOrder() {
        return 3;
    }
}

执行结果为

  1. main before run
  2. second args[0]: param1
  3. second CommandLineRunner.run()
  4. first args[0]: param1
  5. first CommandLineRunner.run()
  6. third args[0]: param1
  7. third CommandLineRunner.run()
  8. main after run

    ApplicationRunner

    ApplicationRunner接口和CommandLineRunner功能用法一致，唯一不同是对args参数进行了封装，run方法传递参数为ApplicationArguments，可以通过**ApplicationArguments.getSourceArgs()**获取字符数组参数args。