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本篇将讲解一下closure中的owner以及thisdelegate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: + ownerdef innerClosure = {println the owner of innerClosure: + ownerdef innestClosure = {println the owner of innestClosure: + owner}innestClosure()}innerClosure()}}def ownerDemo = new OwnerDemo()ownerDemoouterClosure() 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: + ownerprintln the delegate of outerClosure: + delegateprintln this in the outerClosure: + thisdef innerClosure = {println the owner of innerClosure: + ownerprintln the delegate of innerClosure: + delegateprintln this in the innerClosure: + thisdef innestClosure = {println the owner of innestClosure: + ownerprintln the delegate of innestClosure: + delegateprintln this in the innestClosure: + this}println innestClosure: + innestClosureinnestClosure()}println innerClosure: + innerClosureinnerClosure()}}def ownerDemo = new OwnerDemo()def outerClosure = ownerDemoouterClosureprintln outerClosure: + outerClosureouterClosure() 运行结果 outerClosure: OwnerDemo$_closure@ccb the owner of outerClosure: OwnerDemo@ef the delegate of outerClosure: OwnerDemo@ef this in the outerClosure: OwnerDemo@ef innerClosure: OwnerDemo$_closure_closure@ebdb the owner of innerClosure: OwnerDemo$_closure@ccb the delegate of innerClosure: OwnerDemo$_closure@ccb this in the innerClosure: OwnerDemo@ef innestClosure: OwnerDemo$_closure_closure_closure@aee the owner of innestClosure: OwnerDemo$_closure_closure@ebdb the delegate of innestClosure: OwnerDemo$_closure_closure@ebdb this in the innestClosure: OwnerDemo@ef 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:) |
