Spring Boot Integration Picocli Quick Start Demo

1. What is Picocli?

Picocli is a single-file command-line parsing framework that allows you to create command-line applications with little to no code. use @Option or @Parameters Comment on the fields in your app, and Picocli will populate them with command line options and positional arguments, respectively. usePicoclito write a powerful command-line program.

pain point

• There is no full-fledged framework to encapsulateParameter receiving、Parameter hintsandParameter validation
• It’s hard to deal with parametersmutually exclusiveas well as the mutuality of specific commandsDependencies
• Commands cannot be madeAutocomplete
• Since the JVM interprets the execution bytecode and the JIT cannot be usedShort-term executionJava command-line programsSlow start
• After integrating SpringBoot and other components, the startup is even slower

2. Code engineering

Experiment purpose: Use Picocli to write an email sending command

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>picocli</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>info.picocli</groupId>
            <artifactId>picocli-spring-boot-starter</artifactId>
            <version>4.7.6</version>
        </dependency>
        <!--email-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-mail</artifactId>
        </dependency>
    </dependencies>
    <!--<build>
        <finalName>demo1</finalName>
        <plugins>
            <plugin>
                <artifactId>maven-assembly-plugin</artifactId>
                <configuration>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                    <archive>
                        <manifest>
                            <mainClass>com.et.picocli.MySpringMailer</mainClass>
                        </manifest>
                    </archive>
                </configuration>
                <executions>
                    <execution>
                        <id>make-assembly</id>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>-->
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

Startup class

package com.et.picocli;
import com.et.picocli.command.MailCommand;
import org.springframework.boot.*;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import picocli.CommandLine;
import picocli.CommandLine.IFactory;
@SpringBootApplication
public class MySpringMailer implements CommandLineRunner, ExitCodeGenerator {
    private IFactory factory;        
    private MailCommand mailCommand;
    private int exitCode;
    // constructor injection
    MySpringMailer(IFactory factory, MailCommand mailCommand) {
        this.factory = factory;
        this.mailCommand = mailCommand;
    }
    @Override
    public void run(String... args) {
        // let picocli parse command line args and run the business logic
        exitCode = new CommandLine(mailCommand, factory).execute(args);
    }
    @Override
    public int getExitCode() {
        return exitCode;
    }
    public static void main(String[] args) {
        // let Spring instantiate and inject dependencies
        System.exit(SpringApplication.exit(SpringApplication.run(MySpringMailer.class, args)));
    }
}

service

package com.et.picocli.service;
import java.util.List;
public interface IMailService {
    void sendMessage(List<String> to, String subject, String text);
}

package com.et.picocli.service;
import org.slf4j.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.mail.*;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.stereotype.Service;
import java.util.List;
@Service("MailService")
public class MailServiceImpl implements IMailService {
    private static final Logger LOGGER= LoggerFactory.getLogger(MailServiceImpl.class);
    private static final String NOREPLY_ADDRESS = "noreply@picocli.info";
    @Autowired(required = false)
    private JavaMailSender emailSender;
    @Override
    public void sendMessage(List<String> to, String subject, String text) {
        LOGGER.info("  start Mail to {} sent! Subject: {}, Body: {}", to, subject, text);
        try {
            SimpleMailMessage message = new SimpleMailMessage(); // create message
            message.setFrom(NOREPLY_ADDRESS);                    // compose message
            for (String recipient : to) { message.setTo(recipient); }
            message.setSubject(subject);
            message.setText(text);
            emailSender.send(message);                           // send message
            LOGGER.info("  end Mail to {} sent! Subject: {}, Body: {}", to, subject, text);
        }
        catch (MailException e) { e.printStackTrace(); }
    }
}

command

package com.et.picocli.command;
import com.et.picocli.service.IMailService;
import org.springframework.stereotype.Component;
import org.springframework.beans.factory.annotation.Autowired;
import picocli.CommandLine;
import picocli.CommandLine.*;
import java.util.List;
import java.util.concurrent.Callable;
@Component 
//@Command(name = "mailCommand")
@CommandLine.Command(
        subcommands = {
                GitAddCommand.class,
                GitCommitCommand.class
        }
)
public class
MailCommand implements Callable<Integer> {
    @Autowired
    private IMailService mailService;
    @Option(names = "--to", description = "email(s) of recipient(s)", required = true)
    List<String> to;
    @Option(names = "--subject", description = "Subject")
    String subject;
    @Parameters(description = "Message to be sent")
    String[] body = {};
    public Integer call() throws Exception {
        mailService.sendMessage(to, subject, String.join(" ", body)); 
        return 0;
    }
}

application.properties

# configuration mail service
spring.mail.host=smtp.gmail.com
spring.mail.port=587
spring.mail.username=email
spring.mail.password=password
spring.mail.properties.mail.smtp.auth=true
spring.mail.properties.mail.smtp.starttls.enable=true
spring.mail.properties.mail.smtp.starttls.required=true

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 install

Go to the target directory

cd target

Execute the command

//send mail 
java -jar picocli-1.0-SNAPSHOT.jar --to ss@163.com --subject testmail text 111111
//sub command
java -jar picocli-1.0-SNAPSHOT.jar --to ss@163.com --subject testmail text 111111 add

Print help

java -jar picocli-1.0-SNAPSHOT.jar --help

4. References

• https://picocli.info/#_spring_boot_example
• http://www.liuhaihua.cn/archives/710560.html