• 閉包定義與調(diào)用

    //默認(rèn)參數(shù) it
    Closure c = {
        it+5
    }

    //顯式命名參數(shù)，此時(shí)就沒有it
    Closure d = { k ->
        k+5
    }
    
    //閉包的調(diào)用
    c.call(7)

*動(dòng)態(tài)閉包

    def f(Closure closure){
        //根據(jù)閉包的參數(shù)的個(gè)數(shù)執(zhí)行不同的邏輯
        if (closure.maximumNumberOfParameters == 2){}
        else{}   
        
        for (param in closure.parameterTypes){
            param.name //參數(shù)的類型
        }
    }

    //不同參個(gè)數(shù)的閉包調(diào)用的內(nèi)部邏輯是不一樣的
    f{ param1 -> }
    f{ param1,param2 -> }

• this、owner、delegate
  閉包里面有3個(gè)重要的對(duì)象，把它們弄清楚了，才能對(duì)一些代碼有全面的理解
  this:創(chuàng)建閉包的對(duì)象（上下文）
  owner：如果閉包在另外一個(gè)閉包中創(chuàng)建，owner指向另一個(gè)的閉包，否則指向this
  delegate：默認(rèn)指向owner，但可以設(shè)置為其他對(duì)象

閉包里面的屬性和方法調(diào)用與三個(gè)對(duì)象有密切的關(guān)系，閉包中有個(gè)resolveStrategy，默認(rèn)值為0

    public static final int OWNER_FIRST = 0;
    public static final int DELEGATE_FIRST = 1;
    public static final int OWNER_ONLY = 2;
    public static final int DELEGATE_ONLY = 3;

屬性或者方法調(diào)用的查找順序
OWNER_FIRST:
own -> this -> delegate

DELEGATE_FIRST
delegate->own -> this

class Hello {

//    def a = "hello a"
    def innerC

    def c = {
//        def a = "closure a"

        innerC = {
            println(a)
        }

        delegate = new Delegate()

        //修改閉包的delegate
        innerC.delegate = delegate
        //設(shè)置閉包的代理策略
        innerC.setResolveStrategy(Closure.OWNER_FIRST)

        innerC.call()
    }

    def f(){
        c.call()
    }

}

class Delegate {
    def a = "delegate a"
}