闭包的三个重要变量: this owner delegate

//闭包的三个重要变量: this owner delegate
def scriptClouser = {
    println "scriptClouser this: " + this //代表闭包定义处的类
    println "scriptClouser owner: " + owner //代表闭包定义处的类或对象
    println "scriptClouser delegate: " + delegate //代表任意对象
}
scriptClouser.call()

//定义了一个内部类
class Person {
    def static classClouser = {
        println "classClouser this: " + this //代表闭包定义处的类
        println "classClouser owner: " + owner //代表闭包定义处的类或对象 (闭包可以定义在闭包内,此时为对象)
        println "classClouser delegate: " + delegate //代表任意对象
    }

    def static say() {
        def methodClouser = {
            println "methodClouser this: " + this //代表闭包定义处的类
            println "methodClouser owner: " + owner //代表闭包定义处的类或对象
            println "methodClouser delegate: " + delegate //代表任意对象
        }
        classClouser.call()
    }
}
println "-----------------"
Person.classClouser.call()
println "-----------------"
Person.say()

结果

scriptClouser this: com.cjt.groovy.variable.004clouserstudy@6682e6a5
scriptClouser owner: com.cjt.groovy.variable.004clouserstudy@6682e6a5
scriptClouser delegate: com.cjt.groovy.variable.004clouserstudy@6682e6a5
-----------------
classClouser this: class com.cjt.groovy.variable.Person
classClouser owner: class com.cjt.groovy.variable.Person
classClouser delegate: class com.cjt.groovy.variable.Person
-----------------
classClouser this: class com.cjt.groovy.variable.Person
classClouser owner: class com.cjt.groovy.variable.Person
classClouser delegate: class com.cjt.groovy.variable.Person

上例子中如果去年类中的static

//定义了一个内部类
class Person {
    def   classClouser = {
        println "classClouser this: " + this //代表闭包定义处的类
        println "classClouser owner: " + owner //代表闭包定义处的类或对象 (闭包可以定义在闭包内,此时为对象)
        println "classClouser delegate: " + delegate //代表任意对象
    }

    def   say() {
        def methodClouser = {
            println "methodClouser this: " + this //代表闭包定义处的类
            println "methodClouser owner: " + owner //代表闭包定义处的类或对象
            println "methodClouser delegate: " + delegate //代表任意对象
        }
        classClouser.call()
    }
}
//println "-----------------"
//Person.classClouser.call()
//println "-----------------"
//Person.say()

//如果上面去年static, Person p = new Person 用p.classClouser.call()
println "-----------------"
Person p = new Person()
p.classClouser.call()
println "-----------------"
p.say()

结果是都一样的,指向类实例

classClouser this: com.cjt.groovy.variable.Person@1192c925
classClouser owner: com.cjt.groovy.variable.Person@1192c925
classClouser delegate: com.cjt.groovy.variable.Person@1192c925
-----------------
classClouser this: com.cjt.groovy.variable.Person@1192c925
classClouser owner: com.cjt.groovy.variable.Person@1192c925
classClouser delegate: com.cjt.groovy.variable.Person@1192c925

如果是闭包中定义闭包 三个变量才会不一样

def nestClouser = {
    def innerClouser = {
        println "innerClouser this: " + this          //com.cjt.groovy.variable.clouserstudy@74834afd
        println "innerClouser owner: " + owner        //com.cjt.groovy.variable.clouserstudy$_run_closure12@62cba181
        println "innerClouser delegate: " + delegate  //com.cjt.groovy.variable.clouserstudy$_run_closure12@62cba181
    }
    //innerClouser.delegate = p //修改默认的delegate
    innerClouser.call()
}
nestClouser.call()

结果

innerClouser this: com.cjt.groovy.variable.004clouserstudy@22048bd6
innerClouser owner: com.cjt.groovy.variable.004clouserstudy$_run_closure12@5cc1bf20
innerClouser delegate: com.cjt.groovy.variable.004clouserstudy$_run_closure12@5cc1bf20