Jenkins Pipline实现及原理示例解析

def greet(String name) {
    println("Hello, $name!")
}
// 使用括号调用方法
greet("Alice")  // 输出: Hello, Alice!
// 省略括号，将参数作为闭包的一部分传递
greet "Bob"    // 输出: Hello, Bob!

def closure = { param ->
    println("Hello, $param!")
}

def printSum = { a, b ->
    println(a + b)
}

closure("Alice")  // 输出: Hello, Alice!
printSum(3, 5)   // 输出: 8

def processData(data, closure) {
// 执行某些逻辑...
    closure(data)
}
processData("Hello", { input ->
    println("Received: $input")
})

class Person {
    String name
    void sayHello() {
        println("Hello, I'm $name")
    }
}
def person = new Person(name: "Alice")
def closure = { sayHello() }  // 使用闭包代理调用Person对象的sayHello方法
closure.delegate = person
closure()  // 输出: Hello, I'm Alice

import static Dsl.pipeline
pipeline {
    agent any
    environment {
        SOME_NUMBER = 123
        SOME_STRING = "foobar"
    }
    stages {
        stage("Build") {
            steps { env ->
                sh "ls -la"
                sh(script: 'date +%Y-%m-%d', returnStdout: false)
                echo "Groovy rocks!"
                echo "env.SOME_STRING = ${env.SOME_STRING}"
            }
        }
        stage("Test") {
            steps {
                sh """ 
                    echo "Testing..." 
                    """
            }
        }
    }
}

import groovy.transform.NamedParam
import groovy.transform.NamedParams
import groovy.transform.stc.ClosureParams
import groovy.transform.stc.SimpleType
import java.util.concurrent.ConcurrentHashMap
import java.util.concurrent.ConcurrentMap
import static groovy.lang.Closure.DELEGATE_FIRST
import static groovy.lang.Closure.DELEGATE_ONLY
class Dsl {
    static void pipeline(@DelegatesTo(value = PipelineDsl, strategy = DELEGATE_ONLY) final Closure closure) {
        final PipelineDsl dsl = new PipelineDsl()
        closure.delegate = dsl
        closure.resolveStrategy = DELEGATE_ONLY
        closure.call()
    }
}
class PipelineDsl {
    // 定义一个占位符常量
    final Placeholder any = Placeholder.ANY
    // 使用 ConcurrentHashMap 创建环境变量的并发映射
    static final ConcurrentMap<String, String> env = [:] as ConcurrentHashMap
    // 定义 agent 方法
    void agent(final Placeholder any) {
        println "Running pipeline using any available agent..."
    }
    // 定义 environment 方法
    void environment(@DelegatesTo(value = Map, strategy = DELEGATE_FIRST) final Closure closure) {
        // 将闭包委托给 env 并执行闭包
        env.with(closure)
    }
    // 定义 stages 方法
    void stages(@DelegatesTo(value = StagesDsl, strategy = DELEGATE_ONLY) final Closure closure) {
        final StagesDsl dsl = new StagesDsl()
        closure.delegate = dsl
        closure.resolveStrategy = DELEGATE_ONLY
        closure.call()
        // 遍历 stages 列表并依次运行每个 stage
        dsl.stages.each { stage ->
            stage.run()
        }
    }
    // 定义占位符枚举类
    enum Placeholder {
        ANY
    }
}
class StagesDsl {
    // 定义 stages 列表
    protected final List<Stage> stages = []
    // 定义 stage 方法
    void stage(final String name, @DelegatesTo(value = StageDsl, strategy = DELEGATE_ONLY) final Closure closure) {
        // 将 stage 添加到 stages 列表中
        stages << new Stage(name, closure)
    }
}
class Stage {
    final String name
    final Closure closure
    // 定义 Stage 类的构造函数
    Stage(String name, Closure closure) {
        this.name = name
        this.closure = closure
    }
    // 运行 stage 的方法
    void run() {
        println "==> Running '${name}' stage..."
        final StageDsl dsl = new StageDsl()
        closure.delegate = dsl
        closure.resolveStrategy = DELEGATE_ONLY
        closure.call()
    }
}
class StageDsl {
    // 定义 steps 方法
    void steps(
            @DelegatesTo(value = Steps, strategy = DELEGATE_ONLY)
            @ClosureParams(value = SimpleType, options = ["java.util.Map"]) final Closure closure) {
        final Steps steps = new Steps()
        closure.delegate = steps
        closure.resolveStrategy = DELEGATE_ONLY
        closure.call(PipelineDsl.env)
    }
}
class Steps {
    // 定义 sh 方法
    void sh(final String script) {
            sh(script: script, returnStdout: false)
    }
    // 定义重载的 sh 方法
    Object sh(@NamedParams([
            @NamedParam(value = "script", type = String, required = true),
            @NamedParam(value = "returnStdout", type = Boolean)
    ]) final Map param) {
        // 执行 shell 脚本，并等待执行完成
        final Process p = param.script.toString().execute()
        p.waitFor()
        println "+ ${param.script}"
        if (p.exitValue() == 0) {
            if (param.returnStdout) {
                return p.text
            }
            println p.text
        } else {
            println p.err.text
        }
    }
    // 定义 echo 方法
    void echo(final String message) {
        println "[ECHO] ${message}"
    }
}

// 静态导入列pipline方法
import static Dsl.pipeline
// 调用pipeline方法, 传入一个闭包; 方法调用可以省略（） ； pipline {...} 等同于 pipeline({ ... })
pipeline { // pipeline的参数是一个闭包，该闭包被委托给PipelineDsl类处理，所以在闭包内可以直接调用PipelineDsl内部的方法
    // 调用PipelineDsl#agent(any)
    agent any
    // 调用PipelineDsl#environment(closure)
    environment {
        SOME_NUMBER = 123
        SOME_STRING = "foobar"
    }
    // 调用PipelineDsl#stages(closure)
    stages { // stages的参数是一个闭包，该闭包被委托给StagesDsl类处理,所以可以直接调用StagesDsl内部的方法
        // 调用StagesDsl#stage(name, closure)
        stage("Build") { // stage的参数是一个闭包，该闭包被委托给StageDsl类处理,所以可以直接调用StageDsl内部的方法
            // 调用StageDsl#steps(closure)
            steps { env ->   // steps的参数是一个闭包，该闭包被委托给Steps类处理,所以可以直接调用Steps内部的方法
                // 调用Steps#sh(script)
                sh "ls -la"
                // 调用Steps#sh(script, returnStdout)
                sh(script: 'date +%Y-%m-%d', returnStdout: false)
                // 调用Steps#echo(message)
                echo "Groovy rocks!"
                // 调用Steps#echo(message)
                echo "env.SOME_STRING = ${env.SOME_STRING}"
            }
        }
        // 省略... 
        stage("Test") {
            steps {
                sh """ 
                    echo "Testing..." 
                    """
            }
        }
    }
}