23.SpringApplication

SpringApplication类使用main()方法来方便的方式来引导Spring application的启动.在许多情况下，你可以委托给静态SpringApplication.run方法:

public static void main(String[] args) {
    SpringApplication.run(MySpringConfiguration.class, args);
}

一般的启动失败大都是因为端口(8080)被占用

启动打印的横幅可以自定义

Variable	Description
`${application.version}`	The version number of your application as declared in `MANIFEST.MF`. For example `Implementation-Version: 1.0` is printed as `1.0`.
`${application.formatted-version}`	The version number of your application as declared in `MANIFEST.MF` formatted for display (surrounded with brackets and prefixed with `v`). For example `(v1.0)`.
`${spring-boot.version}`	The Spring Boot version that you are using. For example `1.5.9.RELEASE`.
${spring-boot.formatted-version}	The Spring Boot version that you are using formatted for display (surrounded with brackets and prefixed with `v`). For example `(v1.5.9.RELEASE)`.
`${Ansi.NAME}` (or `${AnsiColor.NAME}`, `${AnsiBackground.NAME}`, `${AnsiStyle.NAME}`)	Where `NAME` is the name of an ANSI escape code. See `AnsiPropertySource` for details.
`${application.title}`	The title of your application as declared in `MANIFEST.MF`. For example`Implementation-Title: MyApp` is printed as `MyApp`.

yaml 可以禁用横幅
spring:
    main:
        banner-mode: "off"

Accessing application arguments

访问应用程序参数

可以注入一个org.springframework.boot.ApplicationArgumentsbean,来访问程序参数.

import org.springframework.boot.*
import org.springframework.beans.factory.annotation.*
import org.springframework.stereotype.*

@Component
public class MyBean {

    @Autowired //注入args[]
    public MyBean(ApplicationArguments args) {
        boolean debug = args.containsOption("debug");
        List<String> files = args.getNonOptionArgs();
        // if run with "--debug logfile.txt" debug=true, files=["logfile.txt"]
    }

}

使用ApplicationRunner或CommandLineRunner

你可以通过实现ApplicationRunner 和CommandLineRunner 这两个接口来在启动时运行一些特殊的代码once,这两个接口都以相同的方式工作,并提供一个run方法,将在SpringApplication.run() 完成之前调用.

CommandLineRunner 接口使用一个简单的String[] 提供对应用程序参数的访问,而ApplicationRunner 则使用ApplicationArguments 接口

import org.springframework.boot.*
import org.springframework.stereotype.*

@Component
public class MyBean implements CommandLineRunner {

    public void run(String... args) {
        // Do something...
    }

}

程序退出

如果bean 在SpringApplication.exit() 调用时希望返回一个特定的退出代码，它们可以实现org.springframework.boot.ExitCodeGenerator 接口.这个退出代码然后可以被传递给System.exit()作为状态代码返回它.

@SpringBootApplication
public class ExitCodeApplication {

    @Bean
    public ExitCodeGenerator exitCodeGenerator() {
        return new ExitCodeGenerator() {
            @Override
            public int getExitCode() {
                return 42;
            }
        };
    }

    public static void main(String[] args) {
        System.exit(SpringApplication           .exit(SpringApplication.run(ExitCodeApplication.class, args)));
    }

}