Getting Started

要了解 Spring Shell 提供的内容，我们可以编写一个简单的 _hello world_shell 应用程序，其中包含一个简单的参数。

To see what Spring Shell has to offer, we can write a trivial hello world shell application that has a simple argument.

Spring Shell_基于_Spring Boot {spring-boot-version} 和 Spring Framework current，因此需要_JDK 17_。

Spring Shell is based on Spring Boot {spring-boot-version} and Spring Framework current and thus requires JDK 17.

Creating a Project

为了完成本教程，我们通过使用 [role="bare"][role="bare"]https://start.spring.io 创建了一个简单的 Spring Boot 应用程序，其中可以选择 Spring Shell 依赖项。此最小应用程序仅依赖于 spring-boot-starter 和 spring-shell-starter。

For the purpose of this tutorial, we create a simple Spring Boot application by using [role="bare"]https://start.spring.io where you can choose Spring Shell dependency. This minimal application depends only on spring-boot-starter and spring-shell-starter.

_Spring Shell_在`start.spring.io`上的版本通常是最新版本。

Spring Shell version on start.spring.io is usually latest release.

使用 maven，您应该具有类似以下内容：

With maven you’re expected to have something like:

<properties>
    <spring-shell.version>{project-version}</spring-shell.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.shell</groupId>
        <artifactId>spring-shell-starter</artifactId>
    </dependency>
</dependencies>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.shell</groupId>
            <artifactId>spring-shell-dependencies</artifactId>
            <version>${spring-shell.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

使用 gradle，您应该具有类似以下内容：

With gradle you’re expected to have something like:

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter'
    implementation 'org.springframework.shell:spring-shell-starter'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
}

dependencyManagement {
    imports {
        mavenBom "org.springframework.shell:spring-shell-dependencies:{project-version}"
    }
}

鉴于 Spring Shell 启动 REPL (Read-Eval-Print-Loop)，因为存在此依赖项，因此你需要在整个本教程中构建 (-DskipTests) 时跳过测试或删除由 [role="bare"][role="bare"]https://start.spring.io 生成的示例集成测试。如果你不将其删除，则集成测试将创建 Spring ApplicationContext，并且根据你的构建工具将停滞在 eval 循环中或因 NPE 而崩溃。

Given that Spring Shell starts the REPL (Read-Eval-Print-Loop) because this dependency is present, you need to either skip tests when you build (-DskipTests) throughout this tutorial or remove the sample integration test that was generated by [role="bare"]https://start.spring.io. If you do not remove it, the integration test creates the Spring ApplicationContext and, depending on your build tool, stays stuck in the eval loop or crashes with a NPE.

编译后，可以在交互模式下运行：

Once compiled it can be run either in interactive mode:

$ $JAVA_HOME/bin/java -jar demo-0.0.1-SNAPSHOT.jar

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::       (v{spring-boot-version})

2022-09-13T18:42:12.818+01:00  INFO 12644 --- [           main] com.example.demo.DemoApplication
: Starting DemoApplication using Java 17.0.4 on ...
2022-09-13T18:42:12.821+01:00  INFO 12644 --- [           main] com.example.demo.DemoApplication
: No active profile set, falling back to 1 default profile: "default"
2022-09-13T18:42:13.606+01:00  INFO 12644 --- [           main] com.example.demo.DemoApplication
: Started DemoApplication in 1.145 seconds (process running for 1.578)
shell:>help
AVAILABLE COMMANDS

Built-In Commands
       help: Display help about available commands
       stacktrace: Display the full stacktrace of the last error.
       clear: Clear the shell screen.
       quit, exit: Exit the shell.
       history: Display or save the history of previously run commands
       version: Show version info
       script: Read and execute commands from a file.

或者在非交互模式下运行：

Or in non-interactive mode:

$JAVA_HOME/bin/java -jar demo-0.0.1-SNAPSHOT.jar help

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::       (v{spring-boot-version})

2022-09-13T18:42:12.818+01:00  INFO 12644 --- [           main] com.example.demo.DemoApplication
: Starting DemoApplication using Java 17.0.4 on ...
2022-09-13T18:42:12.821+01:00  INFO 12644 --- [           main] com.example.demo.DemoApplication
: No active profile set, falling back to 1 default profile: "default"
2022-09-13T18:42:13.606+01:00  INFO 12644 --- [           main] com.example.demo.DemoApplication
: Started DemoApplication in 1.145 seconds (process running for 1.578)
AVAILABLE COMMANDS

Built-In Commands
       help: Display help about available commands
       stacktrace: Display the full stacktrace of the last error.
       clear: Clear the shell screen.
       quit, exit: Exit the shell.
       history: Display or save the history of previously run commands
       version: Show version info
       script: Read and execute commands from a file.

查看 Logging，让日志记录与 shell 应用程序配合得更好。

Check out Logging making logging to work better with shell apps.

Your First Command

现在我们可以添加我们的第一个命令。为此，创建一个新类（命名为任何您想要的内容），并使用 @ShellComponent 对其进行注释，这是 @Component 的一个变体，用于限制扫描候选命令的类集。

Now we can add our first command. To do so, create a new class (named whatever you want) and annotate it with @ShellComponent which is a variation of @Component that is used to restrict the set of classes that are scanned for candidate commands.

然后，我们可以创建一个 helloWorld 方法，该方法取 String 作为参数，并返回带有“Hello world”的 String。添加 @ShellMethod 并使用 key 参数有选择地更改命令名称。如果在运行命令时没有给出，您可以使用 @ShellOption 来定义参数默认值。

Then we can create a helloWorld method that takes String as an argument and returns it with "Hello world". Add @ShellMethod and optionally change command name using key parameter. You can use @ShellOption to define argument default value if it’s not given when running a command.

import org.springframework.shell.standard.ShellComponent;
import org.springframework.shell.standard.ShellMethod;
import org.springframework.shell.standard.ShellOption;

@ShellComponent
public class MyCommands {

	@ShellMethod(key = "hello-world")
	public String helloWorld(
		@ShellOption(defaultValue = "spring") String arg
	) {
		return "Hello world " + arg;
	}
}

新的 hello-world 命令对 help 可见：

New hello-world command becomes visible to help:

My Commands
       hello-world:

您可以运行它：

And you can run it:

shell:>hello-world
Hello world spring

shell:>hello-world --arg boot
Hello world boot

本文档的其余部分将深入探讨整个 Spring Shell 编程模型。

The rest of this document delves deeper into the whole Spring Shell programming model.