springboot 02 -ApplicationRunner,CommandLineRunner

    在实际的业务场景中，有时候我们需要在服务启动的时候，执行一些初始化的工作，比如读取配置文件信息，向注册中心注册服务等。springboot提供了ApplicationRunner，CommandLineRunner这两个接口来帮助我们执行初始化工作。当存在多个接口的时候，用@Order（number）  表示执行顺序，数字越小优先级越高。

@Component
@Order(2)
public class MyCommandLinerRunner implements CommandLineRunner {

    @Override
    public void run(String... args) throws Exception {
        System.out.println(args[0]);    //--app.name=apple
        System.out.println("MyCommandLinerRunner.......");
    }
}

@Component
@Order(1)
public class MyCommandLinerRunner1 implements CommandLineRunner {

    @Override
    public void run(String... args) throws Exception {
　　　　　System.out.printin(args[0]);  //--app.name=apple
        System.out.println("MyCommandLinerRunner1.......");
    }
}


@Component
@Order(3)
public class MyApplicationRunner implements ApplicationRunner {
    @Override
    public void run(ApplicationArguments args) throws Exception {

        System.out.println(args.getOptionNames());   //[app.name]
        System.out.println(args.getOptionValues("app.name"));   //[apple]
        System.out.println(args.getSourceArgs());

    }
}

/**
 * Created by IntelliJ IDEA.
 * User: chenzhubing
 * Date: 2019/7/25
 * <p>
 * 1.CommandLineRunner : 应用初始化完成后执行
 * 2.CommandLineRunner实现类只要注册到spring中，即可触发run方法
 * 3.多个CommandLineRunner存在时，通过@Order 标注先后顺序
 */
@SpringBootApplication(scanBasePackages = "com.example.commandLineRunner")
public class SpringbootApplication_runner {

    public static void main(String[] args) {
        SpringApplication springApplication = new SpringApplication(SpringbootApplication_runner.class);
        ConfigurableApplicationContext context = springApplication.run(args);
        context.close();
    }

}

 

 

 

ApplicationRunner和CommandLineRunner两个接口的区别在于run方法的参数不同：

   ApplicationRunner--run：ApplicationArguments，除了可以获取原生参数（main方法里面 的String[] args）,还可以获取指定格式的命令行参数信息，

/**
 * Return the raw unprocessed arguments that were passed to the application.
 * @return the arguments
 */

String[] getSourceArgs();

/**
 * Return the names of all option arguments. For example, if the arguments were
 * "--foo=bar --debug" would return the values {@code ["foo", "debug"]}.
 * @return the option names or an empty set
 */

Set<String> getOptionNames();

/**
 * Return the collection of values associated with the arguments option having the
 * given name.
 * <ul>
 * <li>if the option is present and has no argument (e.g.: "--foo"), return an empty
 * collection ({@code []})</li>
 * <li>if the option is present and has a single value (e.g. "--foo=bar"), return a
 * collection having one element ({@code ["bar"]})</li>
 * <li>if the option is present and has multiple values (e.g. "--foo=bar --foo=baz"),
 * return a collection having elements for each value ({@code ["bar", "baz"]})</li>
 * <li>if the option is not present, return {@code null}</li>
 * </ul>
 * @param name the name of the option
 * @return a list of option values for the given name
 */

List<String> getOptionValues(String name);

  CommandLineRunner--run：String[] args ,来自于main方法里面的String[] args