1.什么是Picocli？

Picocli是一个单文件命令行解析框架，它允许您创建命令行应用而几乎不需要代码。使用 @Option 或 @Parameters 在您的应用中注释字段，Picocli将分别使用命令行选项和位置参数填充这些字段。使用Picocli来编写一个功能强大的命令行程序。

痛点

没有成熟的框架来封装参数接收、参数提示以及参数校验
很难处理参数的互斥以及特定命令的相互依赖关系
无法进行命令自动补全
由于JVM解释执行字节码，并且JIT无法在短时执行中发挥作用，Java命令行程序启动缓慢
集成SpringBoot及其它组件后，启动更加缓慢

2.代码工程

实现目的：使用Picocli编写一个邮件发送命令

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>

启动类

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;
@SpringBootApplicationpublic 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 servicespring.mail.host=smtp.gmail.comspring.mail.port=587spring.mail.username=emailspring.mail.password=passwordspring.mail.properties.mail.smtp.auth=truespring.mail.properties.mail.smtp.starttls.enable=truespring.mail.properties.mail.smtp.starttls.required=true

以上只是一些关键代码，所有代码请参见下面代码仓库

代码仓库

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

3.测试

打包Spring Boot应用程序

mvn install

进入target目录

cd target

执行命令

//发送邮件 java -jar picocli-1.0-SNAPSHOT.jar --to ss@163.com --subject testmail text 111111//执行子命令java -jar picocli-1.0-SNAPSHOT.jar --to ss@163.com --subject testmail text 111111 add

打印help

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

4.引用

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

ITPub博客

Spring Boot集成Picocli快速入门Demo