Groovy 类名称赋值为变量使用（newInstance & new）

类创建实例一般方式

http://groovy-lang.org/objectorientation.html#_class

class Person {                       

    String name
    Integer age

    def increaseAge(Integer years) {
        this.age += years
    }
}

def p = new Person()

类作为参数传递

有些场景下，需要将类作为变量传递

http://groovy-lang.org/objectorientation.html#_class

class Runner {
    static <T> T run(Class<T> taskClass) {
        def tasks = taskClass.newInstance()
        def params = [jdk:6, windows: false]
        tasks.class.declaredMethods.each { m ->
            if (Modifier.isPublic(m.modifiers) && m.parameterTypes.length == 0) {
                def onlyIf = m.getAnnotation(OnlyIf)
                if (onlyIf) {
                    Closure cl = onlyIf.value().newInstance(tasks,tasks)
                    cl.delegate = params
                    if (cl()) {
                        m.invoke(tasks)
                    }
                } else {
                    m.invoke(tasks)
                }
            }
        }
        tasks
    }
}

// create a new instance of the class passed as an argument (the task class)

DEMO2 抽象工厂

http://groovy-lang.org/design-patterns.html#_example

def guessFactory = [messages: GuessGameMessages, control: GuessGameControl, converter: GuessGameInputConverter]
def twoupFactory = [messages: TwoupMessages, control: TwoupControl, converter: TwoupInputConverter]

class GameFactory {
    def static factory
    def static getMessages() { return factory.messages.newInstance() }
    def static getControl() { return factory.control.newInstance() }
    def static getConverter() { return factory.converter.newInstance() }
}

GameFactory.factory = twoupFactory
def messages = GameFactory.messages
def control = GameFactory.control
def converter = GameFactory.converter
println messages.welcome
def reader = new BufferedReader(new InputStreamReader(System.in))
while (control.moreTurns()) {
    def input = reader.readLine().trim()
    control.play(converter.convert(input))
}
println messages.done

DEMO3 -- 变量

class Greet {
    def salute() { println "Hello !" }
}
 
g = new Greet()  // create object
g.salute()

def  class_var = Greet
// h = new class_var()
h = class_var.newInstance()
h.salute()