知识大全 Groovy解惑——closure中的owner

Posted 2022-07-19 知

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　　本篇将讲解一下closure中的owner 以及this delegate以及owner三者间的关系

　　先让我们来看个例子

　　　　class OwnerDemo 　　def outerClosure = 　　println the owner of outerClosure: + owner 　　def innerClosure = 　　println the owner of innerClosure: + owner 　　def innestClosure = 　　println the owner of innestClosure: + owner 　　　　innestClosure() 　　　　innerClosure() 　　　　　　def ownerDemo = new OwnerDemo() 　　ownerDemo outerClosure()

　　运行结果

　　the owner of outerClosure: OwnerDemo@eccfe

　　the owner of innerClosure: OwnerDemo$_closure @ cf

　　the owner of innestClosure: OwnerDemo$_closure _closure @ dcbb

　　注意 OwnerDemo$_closure 指的是outerClosure的类名而OwnerDemo$_closure _closure 指的是innerClosure的类名

　　通过这个例子大家就清楚了 closure的owner引用的是该closure的拥有者

　　那么this delegate以及owner有什么关系呢?

　　隐式变量delegate的默认值为owner

　　如果closure没有嵌套在其他closure中那么该closure的owner的值为this;

　　否则该closure的owner引用的是直接包含该closure的closure

　　让我们用事实来说话吧

　　　　class OwnerDemo 　　def outerClosure = 　　println the owner of outerClosure: + owner 　　println the delegate of outerClosure: + delegate 　　println this in the outerClosure: + this 　　def innerClosure = 　　println the owner of innerClosure: + owner 　　println the delegate of innerClosure: + delegate 　　println this in the innerClosure: + this 　　def innestClosure = 　　println the owner of innestClosure: + owner 　　println the delegate of innestClosure: + delegate 　　println this in the innestClosure: + this 　　　　println innestClosure: + innestClosure 　　innestClosure() 　　　　println innerClosure: + innerClosure 　　innerClosure() 　　　　　　def ownerDemo = new OwnerDemo() 　　def outerClosure = ownerDemo outerClosure 　　println outerClosure: + outerClosure 　　outerClosure()

　　运行结果

　　outerClosure: OwnerDemo$_closure @ cc b

　　the owner of outerClosure: OwnerDemo@ e f

　　the delegate of outerClosure: OwnerDemo@ e f

　　this in the outerClosure: OwnerDemo@ e f

　　innerClosure: OwnerDemo$_closure _closure @ eb db

　　the owner of innerClosure: OwnerDemo$_closure @ cc b

　　the delegate of innerClosure: OwnerDemo$_closure @ cc b

　　this in the innerClosure: OwnerDemo@ e f

　　innestClosure: OwnerDemo$_closure _closure _closure @ a ee

　　the owner of innestClosure: OwnerDemo$_closure _closure @ eb db

　　the delegate of innestClosure: OwnerDemo$_closure _closure @ eb db

　　this in the innestClosure: OwnerDemo@ e f

　　大家可以从其中值的关系看出this delegate以及owner三者的关系与我们之前所说的相符　:)

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