Spring Boot Integration Spring Shell Quick Start Demo

3 min readMay 18, 2024

1. What is Spring Shell?

Spring Shell is a member of the Spring ecosystem for developing command-line applications.https://projects.spring.io/spring-shell/ 。 Spring Shell is built onJLineOn top of that, integratedBean Validation APIImplement command parameter validation. Since version 2.0, Spring Shell can also be easily integrated with Spring Boot, directly using some of the very useful features provided by Spring Boot (e.g., packaging executable jar files).

2. Code engineering

Purpose: To test various Spring shell functions

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springboot-demo</artifactId>
        <groupId>com.et</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
<artifactId>Spring-Shell</artifactId>
    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.shell</groupId>
            <artifactId>spring-shell-starter</artifactId>
            <version>2.0.0.RELEASE</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

command

The first hello word example

package com.et.spring.shell.command;
import org.springframework.shell.standard.ShellCommandGroup;
import org.springframework.shell.standard.ShellComponent;
import org.springframework.shell.standard.ShellMethod;
import org.springframework.shell.standard.ShellOption;
import javax.validation.constraints.Size;
import java.util.List;
@ShellComponent
@ShellCommandGroup("HelloWorld")
public class HelloWorld {
    @ShellMethod("Say hello")
    public void hello(@ShellOption(defaultValue = "World")String name) {
        System.out.println("hello, " + name + "!");
    }
}

some examples

package com.et.spring.shell.command;
import org.springframework.shell.standard.ShellCommandGroup;
import org.springframework.shell.standard.ShellComponent;
import org.springframework.shell.standard.ShellMethod;
import org.springframework.shell.standard.ShellOption;
import javax.validation.constraints.Size;
import java.util.List;
@ShellComponent
@ShellCommandGroup("Calculator")
public class Calculator {
    // give multi name
    //@ShellMethod(value = "Add numbers.", key = {"sum", "addition"})
    @ShellMethod(value = "Add numbers.",  key = {"sum", "addition"}, prefix = "-", group = "Cal")
    public void add(int a, int b) {
        int sum = a + b;
        System.out.println(String.format("%d + %d = %d", a, b, sum));
    }
    @ShellMethod("Echo command help")
    public void myhelp(@ShellOption({"-C", "--command"}) String cmd) {
        System.out.println(cmd);
    }
    // params is collection
    @ShellMethod("Add by list")
    public void addByList(@ShellOption(arity = 3) List<Integer> numbers) {
        int s = 0;
        for(int number : numbers) {
            s += number;
        }
        System.out.println(String.format("s=%d", s));
    }
    @ShellMethod("Echo.")
    public void echo(String what) {
        System.out.println(what);
    }
    // use @Size validate param length
    @ShellMethod("Change password")
    public void changePwd(@Size(min = 6, max = 30) String pwd) {
        System.out.println(pwd);
    }
}

Controls the order in which commands are executed

package com.et.spring.shell.command;
import org.springframework.shell.Availability;
import org.springframework.shell.standard.ShellCommandGroup;
import org.springframework.shell.standard.ShellComponent;
import org.springframework.shell.standard.ShellMethod;
@ShellComponent
@ShellCommandGroup("Downloader")
public class Downloader {
    private boolean connected = false;
    @ShellMethod("Connect server")
    public void connect() {
        connected = true;
    }
    @ShellMethod("Download file")
    public void download() {
        System.out.println("Downloaded.");
    }
    // download availability
    public Availability downloadAvailability() {
        return connected ? Availability.available():Availability.unavailable("you are not connected");
    }
}

DemoApplication.java

package com.et.spring.shell;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class DemoApplication {
   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }
}

The above are just some of the key codes, all of which can be found in the repositories below

Code repositories

https://github.com/Harries/springboot-demo

3. Testing

Package the Spring Boot application

mvn clean package -Dmaven.test.skip=true

Start the program

java -jar Spring-Shell-1.0-SNAPSHOT.jar

Execute the command, type help, and see all the commands

Execute the command

shell:>sum 1 2
1 + 2 = 3