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spring boot学习(4): 命令行启动

在使用spring boot 构建应用启动时，我们在工作中都是通过命令行来启动应用，有时候会需要一些特定的参数以在应用启动时，做一些初始化的操作。

spring boot 提供了 CommandLineRunner 和 ApplicationRunner 这两个接口供用户使用。

1. `CommandLineRunner`

1.1 声明:

@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;

}

1.2 使用:

package com.example.consoleapplication;

import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

@Component
public class TestRunner implements CommandLineRunner {

    @Override
    public void run(String... args) {
        // Do something...
        for(String arg: args){
            System.out.println(arg);
        }
        System.out.print("test command runner");
    }
}

1.3 运行结果

运行： java -jar build/libs/consoleapplication-0.0.1-SNAPSHOT.jar -sdfsaf sdfas ,

结果如下：

2019-03-16 17:31:56.544  INFO 18679 --- [           main] c.e.consoleapplication.DemoApplication   : No active profile set, falling back to default profiles: default
2019-03-16 17:31:57.195  INFO 18679 --- [           main] c.e.consoleapplication.DemoApplication   : Started DemoApplication in 16.172 seconds (JVM running for 16.65)
-sdfsaf
sdfas
test command runner%

2. `ApplicationRunner`

2.1 声明

/**
 * Interface used to indicate that a bean should <em>run</em> when it is contained within
 * a {@link SpringApplication}. Multiple {@link ApplicationRunner} beans can be defined
 * within the same application context and can be ordered using the {@link Ordered}
 * interface or {@link Order @Order} annotation.
 *
 * @author Phillip Webb
 * @since 1.3.0
 * @see CommandLineRunner
 */
@FunctionalInterface
public interface ApplicationRunner {

    /**
     * Callback used to run the bean.
     * @param args incoming application arguments
     * @throws Exception on error
     */
    void run(ApplicationArguments args) throws Exception;

}

2.2 使用

ApplicationRunner 和 CommandLineRunner 的使用是有差别的：

CommandLineRunner 的使用，只是把参数根据空格分割。
ApplicationRunner 会根据是否匹配 --key=value 来解析参数，
- 能匹配，则为 optional 参数，可用 getOptionValues 获取参数值。
- 不匹配则是 non optional 参数。

package com.example.consoleapplication;

import org.springframework.boot.ApplicationRunner;
import org.springframework.stereotype.Component;
import org.springframework.boot.ApplicationArguments;

@Component
public class TestApplicationRunner implements ApplicationRunner {

    @Override
    public void run(ApplicationArguments args) throws Exception {
        // Do something...
        System.out.println("option arg names" + args.getOptionNames());
        System.out.println("non option+" +  args.getNonOptionArgs());
    }
}

2.3 运行结果

运行命令 java -jar build/libs/consoleapplication-0.0.1-SNAPSHOT.jar -non1 non2 --option=1 ，结果为:

2019-03-16 18:08:08.528  INFO 19778 --- [           main] c.e.consoleapplication.DemoApplication   : No active profile set, falling back to default profiles: default
2019-03-16 18:08:09.166  INFO 19778 --- [           main] c.e.consoleapplication.DemoApplication   : Started DemoApplication in 16.059 seconds (JVM running for 16.56)
test
option arg names[option]
non option+[-non1, non2]-non1
non2
--option=1
test%

可以看到， optional 参数名有 option , non optional 参数有 -non1 和 non2