如何在Java / Groovy中使用getAt（）函数？

Question

Recently I encountered the usage of the method getAt() in Java code. It is used to get the data from a URL (which is sent via GET method by form submit). The URL will be like:

http://192.168.27.55/flight/search?n=airchina

The method was used like name=params.getAt("n") . Then the data was passed to another function by search("n",name) . Can any one please brief me how it works?

Answer 1

getAt() in Groovy has special meaning for collections. It allows one to access elements of the collection using the subscript operator .

Here's the documentation for Map and List : Map#getAt(key) List#getAt(index)

Since it's defined to support some syntactic sugar, you don't really see it ever called directly, since it enables you to instead do something like:

Map foo = [bar: 'baz']
assert foo['bar'] == 'baz'

In your particular case with params , you'd simply use:

params['n']

...to take advantage of getAt() . Alternatively, you could use:

params.n
// or
params.get('n')

Answer 2

params.n

params的文档