《Groovy官方文档》Groovy开发套件-使用集合

(译者注:原文是list literals，直译可以翻译为list字面意思，从下文内容来看指的就是list创建和获取元素，译者意译为list基本用法)

你可以使用如下方式创建一个list，注意[]是一个空list表达式。

def list = [5, 6, 7, 8]
assert list.get(2) == 7
assert list[2] == 7
assert list instanceof java.util.List
def emptyList = []
assert emptyList.size() == 0
emptyList.add(5)
assert emptyList.size() == 1

每一个list表达式都是 java.util.list 的一个实现。

当然，lists也可以用于构造另外一个list:

def list1 = ['a', 'b', 'c']
//construct a new list, seeded with the same items as in list1
def list2 = new ArrayList(list1)
assert list2 == list1 // == checks that each corresponding element is the same
// clone() can also be called
def list3 = list1.clone()
assert list3 == list1

list是一个序列集合的对象(译者注：原文是A list is an ordered collection of objects,从下文的示例代码来看，这里不是有序的意思，而是相当于Java集合里的ArrayList，因此认为翻译为序列比有序更为恰当)：

def list = [5, 6, 7, 8]
assert list.size() == 4
assert list.getClass() == ArrayList // the specific kind of list being used
assert list[2] == 7 // indexing starts at 0
assert list.getAt(2) == 7 // equivalent method to subscript operator []
assert list.get(2) == 7 // alternative method
list[2] = 9
assert list == [5, 6, 9, 8,] // trailing comma OK
list.putAt(2, 10) // equivalent method to [] when value being changed
assert list == [5, 6, 10, 8]
assert list.set(2, 11) == 10 // alternative method that returns old value
assert list == [5, 6, 11, 8]
assert ['a', 1, 'a', 'a', 2.5, 2.5f, 2.5d, 'hello', 7g, null, 9 as byte]
//objects can be of different types; duplicates allowed
assert [1, 2, 3, 4, 5][-1] == 5 // use negative indices to count from the end
assert [1, 2, 3, 4, 5][-2] == 4
assert [1, 2, 3, 4, 5].getAt(-2) == 4 // getAt() available with negative index...
try {
[1, 2, 3, 4, 5].get(-2) // but negative index not allowed with get()
assert false
} catch (e) {
assert e instanceof ArrayIndexOutOfBoundsException
}

List可以当作一个boolean值:

assert ![] // an empty list evaluates as false
//all other lists, irrespective of contents, evaluate as true
assert [1] && ['a'] && [0] && [0.0] && [false] && [null]

迭代一个list上的元素可以使用each和eachWithIndex方法，示例代码如下:

[1, 2, 3].each {
println "Item: $it" // `it` is an implicit parameter corresponding to the current element
}
['a', 'b', 'c'].eachWithIndex { it, i -> // `it` is the current element, while `i` is the index
println "$i: $it"
}

除了上面的用法，通过使用迭代，还可以将某些元素转换为另外一种元素来创建一个新的集合。这也是非常有用的用法。这样的操作，通常叫做映射。在Groovy里可以使用collect方法:

assert [1, 2, 3].collect { it * 2 } == [2, 4, 6]
// shortcut syntax instead of collect
assert [1, 2, 3]*.multiply(2) == [1, 2, 3].collect { it.multiply(2) }
def list = [0]
// it is possible to give `collect` the list which collects the elements
assert [1, 2, 3].collect(list) { it * 2 } == [0, 2, 4, 6]
assert list == [0, 2, 4, 6]

过滤和搜索

Groovy开发套件 在集合操作上提供了许多方法来拓展标准集合，一些方法示例如下:

assert [1, 2, 3].find { it > 1 } == 2 // find 1st element matching criteria
assert [1, 2, 3].findAll { it > 1 } == [2, 3] // find all elements matching critieria
assert ['a', 'b', 'c', 'd', 'e'].findIndexOf { // find index of 1st element matching criteria
it in ['c', 'e', 'g']
} == 2

assert [‘a’, ‘b’, ‘c’, ‘d’, ‘c’].indexOf(‘c’) == 2 // index returned

assert [‘a’, ‘b’, ‘c’, ‘d’, ‘c’].indexOf(‘z’) == -1 // index -1 means value not in list

assert [‘a’, ‘b’, ‘c’, ‘d’, ‘c’].lastIndexOf(‘c’) == 4

assert [1, 2, 3].every { it < 5 } // returns true if all elements match the predicate

assert ![1, 2, 3].every { it < 3 } assert [1, 2, 3].any { it > 2 } // returns true if any element matches the predicate

assert ![1, 2, 3].any { it > 3 }

assert [1, 2, 3, 4, 5, 6].sum() == 21 // sum anything with a plus() method

assert [‘a’, ‘b’, ‘c’, ‘d’, ‘e’].sum {

it == ‘a’ ? 1 : it == ‘b’ ? 2 : it == ‘c’ ? 3 : it == ‘d’ ? 4 : it == ‘e’ ? 5 : 0

// custom value to use in sum

} == 15

assert [‘a’, ‘b’, ‘c’, ‘d’, ‘e’].sum { ((char) it) – ((char) ‘a’) } == 10

assert [‘a’, ‘b’, ‘c’, ‘d’, ‘e’].sum() == ‘abcde’

assert [[‘a’, ‘b’], [‘c’, ‘d’]].sum() == [‘a’, ‘b’, ‘c’, ‘d’]

// an initial value can be provided

assert [].sum(1000) == 1000

assert [1, 2, 3].sum(1000) == 1006

assert [1, 2, 3].join(‘-‘) == ‘1-2-3′ // String joining

assert [1, 2, 3].inject(‘counting: ‘) {

str, item -> str + item // reduce operation

} == ‘counting: 123′

assert [1, 2, 3].inject(0) { count, item ->

count + item

} == 6

下面是使用Groovy在集合中查找最大最小值的标准代码：

def list = [9, 4, 2, 10, 5]
assert list.max() == 10
assert list.min() == 2

// we can use a closure to specify the sorting behaviour

def list2 = [‘abc’, ‘z’, ‘xyzuvw’, ‘Hello’, ‘321’]

assert list2.max { it.size() } == ‘xyzuvw’

assert list2.min { it.size() } == ‘z’

除了使用闭包，你可以使用Comparator来定义一个比较：

Comparator mc = { a, b -> a == b ? 0 : (a a == b ? 0 : (Math.abs(a) a.equals(b) ? 0 : Math.abs(a) a.equals(b) ? 0 : Math.abs(a) < Math.abs(b) ? -1 : 1 } == -1

添加或删除元素

我们可以使用[]来创建一个新的空list，使用<<来追加元素在里面:

def list = []
assert list.empty
list << 5
assert list.size() == 1
list << 7 << 'i' << 11
assert list == [5, 7, 'i', 11]
list << ['m', 'o']
assert list == [5, 7, 'i', 11, ['m', 'o']]
//first item in chain of << is target list
assert ([1, 2] << 3 << [4, 5] << 6) == [1, 2, 3, [4, 5], 6]
//using leftShift is equivalent to using <<
assert ([1, 2, 3] << 4) == ([1, 2, 3].leftShift(4))

我们也可以使用下面的方法来添加元素:

assert [1, 2] + 3 + [4, 5] + 6 == [1, 2, 3, 4, 5, 6]
// equivalent to calling the `plus` method
assert [1, 2].plus(3).plus([4, 5]).plus(6) == [1, 2, 3, 4, 5, 6]
def a = [1, 2, 3]
a += 4 // creates a new list and assigns it to `a`
a += [5, 6]
assert a == [1, 2, 3, 4, 5, 6]
assert [1, *[222, 333], 456] == [1, 222, 333, 456]
assert [*[1, 2, 3]] == [1, 2, 3]
assert [1, [2, 3, [4, 5], 6], 7, [8, 9]].flatten() == [1, 2, 3, 4, 5, 6, 7, 8, 9]
def list = [1, 2]
list.add(3)
list.addAll([5, 4])
assert list == [1, 2, 3, 5, 4]
list = [1, 2]
list.add(1, 3) // add 3 just before index 1
assert list == [1, 3, 2]
list.addAll(2, [5, 4]) //add [5,4] just before index 2
assert list == [1, 3, 5, 4, 2]
list = ['a', 'b', 'z', 'e', 'u', 'v', 'g']
list[8] = 'x' // the [] operator is growing the list as needed
// nulls inserted if required
assert list == ['a', 'b', 'z', 'e', 'u', 'v', 'g', null, 'x']

特别重要的是+操作不能改变一个集合。和<<相比，它会创建一个新的list，这可能通常不是你想要的结果，同时会有性能问题。(译者注:这里和Java中String类型的+操作类似)

Groovy开发套件提供了下面的方法来轻松实现从集合中删除元素:

assert ['a','b','c','b','b'] - 'c' == ['a','b','b','b']
assert ['a','b','c','b','b'] - 'b' == ['a','c']
assert ['a','b','c','b','b'] - ['b','c'] == ['a']
def list = [1,2,3,4,3,2,1]
list -= 3 // creates a new list by removing `3` from the original one
assert list == [1,2,4,2,1]
assert ( list -= [2,4] ) == [1,1]

也可以使用下标操作来删除元素，这样会使原集合发生改变:

def list = [1,2,3,4,5,6,2,2,1]
assert list.remove(2) == 3 // remove the third element, and return it
assert list == [1,2,4,5,6,2,2,1]

有时候你仅仅想删除第一次出现的元素，而不是删除全部匹配的元素，你可以这样是使用remove方法:

def list= ['a','b','c','b','b']
assert list.remove('c') // remove 'c', and return true because element removed
assert list.remove('b') // remove first 'b', and return true because element removed
assert ! list.remove('z') // return false because no elements removed
assert list == ['a','b','b']

清空一个list可以使用clear方法:

def list= ['a',2,'c',4]
list.clear()
assert list == []

Set操作
Groovy开发套件同样也提供了许多方法来方便进行Sets操作

assert 'a' in ['a','b','c'] // returns true if an element belongs to the list
assert ['a','b','c'].contains('a') // equivalent to the `contains` method in Java
assert [1,3,4].containsAll([1,4]) // `containsAll` will check that all elements are found
assert [1,2,3,3,3,3,4,5].count(3) == 4 // count the number of elements which have some value
assert [1,2,3,3,3,3,4,5].count {
it%2==0 // count the number of elements which match the predicate
} == 2
assert [1,2,4,6,8,10,12].intersect([1,3,6,9,12]) == [1,6,12]
assert [1,2,3].disjoint( [4,6,9] )
assert ![1,2,3].disjoint( [2,4,6] )

排序

使用Collections的排序,Groovy提供了许多参数来排序一个lists，从使用闭包到使用比较器，示例代码如下:

assert [6, 3, 9, 2, 7, 1, 5].sort() == [1, 2, 3, 5, 6, 7, 9]
def list = ['abc', 'z', 'xyzuvw', 'Hello', '321']
assert list.sort {
it.size()
} == ['z', 'abc', '321', 'Hello', 'xyzuvw']

def list2 = [7, 4, -6, -1, 11, 2, 3, -9, 5, -13]

assert list2.sort { a, b -> a == b ? 0 : Math.abs(a) < Math.abs(b) ? -1 : 1 } == [-1, 2, 3, 4, 5, -6, 7, -9, 11, -13] Comparator mc = { a, b -> a == b ? 0 : Math.abs(a) < Math.abs(b) ? -1 : 1 }

// JDK 8+ only

// list2.sort(mc)

// assert list2 == [-1, 2, 3, 4, 5, -6, 7, -9, 11, -13]

def list3 = [6, -3, 9, 2, -7, 1, 5]

Collections.sort(list3)

assert list3 == [-7, -3, 1, 2, 5, 6, 9]

Collections.sort(list3, mc)

assert list3 == [1, 2, -3, 5, 6, -7, 9]

复制元素

Groovy开发套件重载了一些操作来对集合进行复制操作:

assert [1, 2, 3] * 3 == [1, 2, 3, 1, 2, 3, 1, 2, 3]
assert [1, 2, 3].multiply(2) == [1, 2, 3, 1, 2, 3]
assert Collections.nCopies(3, 'b') == ['b', 'b', 'b']
// nCopies from the JDK has different semantics than multiply for lists
assert Collections.nCopies(2, [1, 2]) == [[1, 2], [1, 2]] //not [1,2,1,2]

在Groovy里，maps(通常和arrays联系在一起)可以使用 [:] 来创建:

def map = [name: 'Gromit', likes: 'cheese', id: 1234]
assert map.get('name') == 'Gromit'
assert map.get('id') == 1234
assert map['name'] == 'Gromit'
assert map['id'] == 1234
assert map instanceof java.util.Map
def emptyMap = [:]
assert emptyMap.size() == 0
emptyMap.put("foo", 5)
assert emptyMap.size() == 1
assert emptyMap.get("foo") == 5

Map的key默认是字符串类型的,[a:1]和[‘a’:1]是等效的。如果你的变量名字恰好也是a 那就会导致混乱了，可能你是想将 a 的值作为你map的key。如果是这种情况，你必须使用括号来转义，类似下面的例子：

def a = 'Bob'
def ages = [a: 43]
assert ages['Bob'] == null // `Bob` is not found
assert ages['a'] == 43 // because `a` is a literal!
ages = [(a): 43] // now we escape `a` by using parenthesis
assert ages['Bob'] == 43 // and the value is found!

除了map的基本操作，要得到一个map的新的拷贝，可以clone它：

def map = [
simple : 123,
complex: [a: 1, b: 2]
]
def map2 = map.clone()
assert map2.get('simple') == map.get('simple')
assert map2.get('complex') == map.get('complex')
map2.get('complex').put('c', 3)
assert map.get('complex').get('c') == 3

上面的例子得到的就是原始map的一个投影。

Maps可以像你操作Bean那样通过使用属性标记来get/set Map内部的元素。只要key是Groovy识别的字符串:

def map = [name: 'Gromit', likes: 'cheese', id: 1234]
assert map.name == 'Gromit' // can be used instead of map.get('Gromit')
assert map.id == 1234
def emptyMap = [:]
assert emptyMap.size() == 0
emptyMap.foo = 5
assert emptyMap.size() == 1
assert emptyMap.foo == 5

注意:默认情况下map.foo将总是在map中搜索key为foo的元素。这意味着如果一个map钟不含有class的可以，foo.class将会返回null。如果你只是想知道类类型，你必须使用getClass() :

def map = [name: 'Gromit', likes: 'cheese', id: 1234]
assert map.class == null
assert map.get('class') == null
assert map.getClass() == LinkedHashMap // this is probably what you want
map = [1 : 'a',
(true) : 'p',
(false): 'q',
(null) : 'x',
'null' : 'z']
assert map.containsKey(1) // 1 is not an identifier so used as is
assert map.true == null
assert map.false == null
assert map.get(true) == 'p'
assert map.get(false) == 'q'
assert map.null == 'z'
assert map.get(null) == 'x'

通常在Groovy开发套件里，迭代map是用each和eachWithIndex方法。maps的创建也是序列的，也就是说当你迭代一个map的时候，可以保证迭代的顺序就是添加元素的顺序:

def map = [
Bob : 42,
Alice: 54,
Max : 33
]
// `entry` is a map entry
map.each { entry ->
println "Name: $entry.key Age: $entry.value"
}
// `entry` is a map entry, `i` the index in the map
map.eachWithIndex { entry, i ->
println "$i - Name: $entry.key Age: $entry.value"
}
// Alternatively you can use key and value directly
map.each { key, value ->
println "Name: $key Age: $value"
}
// Key, value and i as the index in the map
map.eachWithIndex { key, value, i ->
println "$i - Name: $key Age: $value"
}

添加或删除元素

添加一个元素到map可以使用put，批量操作可以使用putAll:

def defaults = [1: 'a', 2: 'b', 3: 'c', 4: 'd']
def overrides = [2: 'z', 5: 'x', 13: 'x']
def result = new LinkedHashMap(defaults)
result.put(15, 't')
result[17] = 'u'
result.putAll(overrides)
assert result == [1: 'a', 2: 'z', 3: 'c', 4: 'd', 5: 'x', 13: 'x', 15: 't', 17: 'u']

删除一个map钟全部元素可以使用clear方法:

def m = [1:'a', 2:'b']
assert m.get(1) == 'a'
m.clear()
assert m == [:]

使用map基本操作生成的map使用了对象的equals和hashcode方法。这个意味着你不应该使用一个hash code经常改变的对象或者其值不可逆操作的对象放入map。

你使用一个GString来作为map的key也是没有意义的。因为GString的hashcode和String的hashcode并不相等。

def key = 'some key'
def map = [:]
def gstringKey = "${key.toUpperCase()}"
map.put(gstringKey,'value')
assert map.get('SOME KEY') == null

keys,values和entries

我们可以在一个视图里查看keys,values和entries：

def map = [1:'a', 2:'b', 3:'c']
def entries = map.entrySet()
entries.each { entry ->
assert entry.key in [1,2,3]
assert entry.value in ['a','b','c']
}
def keys = map.keySet()
assert keys == [1,2,3] as Set

通过视图(也就是map的key,entry和value)返回的值来操作values是强烈不推荐的方式。因为maps操作已经有很多直接操作的方法。特别地，Groovy依赖于JDK的一些方法并不保证能够安全地操作集合，比如keySet，entrySet或values

过滤和搜索

Groovy开发套件包含过滤，搜索集合方法，这个和 list 是类似的:

def people = [
1: [name:'Bob', age: 32, gender: 'M'],
2: [name:'Johnny', age: 36, gender: 'M'],
3: [name:'Claire', age: 21, gender: 'F'],
4: [name:'Amy', age: 54, gender:'F']
]
def bob = people.find { it.value.name == 'Bob' } // find a single entry
def females = people.findAll { it.value.gender == 'F' }
// both return entries, but you can use collect to retrieve the ages for example
def ageOfBob = bob.value.age
def agesOfFemales = females.collect {
it.value.age
}
assert ageOfBob == 32
assert agesOfFemales == [21,54]
// but you could also use a key/pair value as the parameters of the closures
def agesOfMales = people.findAll { id, person ->
person.gender == 'M'
}.collect { id, person ->
person.age
}
assert agesOfMales == [32, 36]
// `every` returns true if all entries match the predicate
assert people.every { id, person ->
person.age > 18
}
// `any` returns true if any entry matches the predicate
assert people.any { id, person ->
person.age == 54
}

分组

我们可以将一个list按某些维度分组到一个map中:

assert ['a', 7, 'b', [2, 3]].groupBy {
it.class
} == [(String) : ['a', 'b'],
(Integer) : [7],
(ArrayList): [[2, 3]]
]
assert [
[name: 'Clark', city: 'London'], [name: 'Sharma', city: 'London'],
[name: 'Maradona', city: 'LA'], [name: 'Zhang', city: 'HK'],
[name: 'Ali', city: 'HK'], [name: 'Liu', city: 'HK'],
].groupBy { it.city } == [
London: [[name: 'Clark', city: 'London'],
[name: 'Sharma', city: 'London']],
LA : [[name: 'Maradona', city: 'LA']],
HK : [[name: 'Zhang', city: 'HK'],
[name: 'Ali', city: 'HK'],
[name: 'Liu', city: 'HK']],
]

Ranges允许你创建一个序列值得list，它可以当成list用，因为 Range 继承了 java.util.List

Ranges定义使用 .. 代表闭区间(包括起点和终点)

Ranges定义使用 ..< 代表一个半开半闭，只包含第一个值不包含最后一个值。

// an inclusive range
def range = 5..8
assert range.size() == 4
assert range.get(2) == 7
assert range[2] == 7
assert range instanceof java.util.List
assert range.contains(5)
assert range.contains(8)
// lets use a half-open range
range = 5..<8
assert range.size() == 3
assert range.get(2) == 7
assert range[2] == 7
assert range instanceof java.util.List
assert range.contains(5)
assert !range.contains(8)
//get the end points of the range without using indexes
range = 1..10
assert range.from == 1
assert range.to == 10

可以看到创建一个int区间是非常高效的，可以创建一个非常轻量级的包含起点值和终点值得对象。

区间也可以用作实现了Java.lang.Comparable接口作为比较器的任何Java对象。可以使用next()和previous()来返回netx/previous元素。举个例子，你可以创建一个String元素类型的区间：

// an inclusive range
def range = 'a'..'d'
assert range.size() == 4
assert range.get(2) == 'c'
assert range[2] == 'c'
assert range instanceof java.util.List
assert range.contains('a')
assert range.contains('d')
assert !range.contains('e')

你可以使用for循环来迭代区间元素：

for (i in 1..10) {
println "Hello ${i}"
}

当然你也可以使用更加Groovy风格的方式来实现同样的效果，通过使用each方法来迭代区间元素:

(1..10).each { i ->
println "Hello ${i}"
}

区间同样可以用在switch语句中:

switch (years) {
case 1..10: interestRate = 0.076; break;
case 11..25: interestRate = 0.052; break;
default: interestRate = 0.037;
}

幸亏属性标记对Lists和Maps都支持，Groovy 提供了非常实用的方法来使嵌套集合处理变得非常简洁，示例代码如下:

def listOfMaps = [['a': 11, 'b': 12], ['a': 21, 'b': 22]]
assert listOfMaps.a == [11, 21] //GPath notation
assert listOfMaps*.a == [11, 21] //spread dot notation

listOfMaps = [[‘a': 11, ‘b': 12], [‘a': 21, ‘b': 22], null]

assert listOfMaps*.a == [11, 21, null] // caters for null values

assert listOfMaps*.a == listOfMaps.collect { it?.a } //equivalent notation

// But this will only collect non-null values

assert listOfMaps.a == [11,21]

Spread操作可以认为是将一个集合内联到另外一个集合。这样就可以避免使用putAll方法从而将实现变得只要一行代码：

assert [ 'z': 900,
*: ['a': 100, 'b': 200], 'a': 300] == ['a': 300, 'b': 200, 'z': 900]
//spread map notation in map definition
assert [*: [3: 3, *: [5: 5]], 7: 7] == [3: 3, 5: 5, 7: 7]

def f = { [1: ‘u’, 2: ‘v’, 3: ‘w’] }

assert [*: f(), 10: ‘zz’] == [1: ‘u’, 10: ‘zz’, 2: ‘v’, 3: ‘w’]

//spread map notation in function arguments

f = { map -> map.c }

assert f(*: [‘a': 10, ‘b': 20, ‘c': 30], ‘e': 50) == 30

f = { m, i, j, k -> [m, i, j, k] }

//using spread map notation with mixed unnamed and named arguments

assert f(‘e': 100, *[4, 5], *: [‘a': 10, ‘b': 20, ‘c': 30], 6) ==

[[“e”: 100, “b”: 20, “c”: 30, “a”: 10], 4, 5, 6]

星号操作是允许你在一个集合的全部元素中调用某个方法或属性的简洁操作：

assert [1, 3, 5] == ['a', 'few', 'words']*.size()
class Person {
String name
int age
}
def persons = [new Person(name:'Hugo', age:17), new Person(name:'Sandra',age:19)]
assert [17, 19] == persons*.age

你可以使用下标来索引lists,arrays,maps。字符串类型被当成一种特殊的集合类型：

def text = 'nice cheese gromit!'
def x = text[2]

def list = [10, 11, 12, 13]

def answer = list[2,3]

assert answer == [12,13]

注意你可以使用区间来提取集合：

list = 100..200
sub = list[1, 3, 20..25, 33]
assert sub == [101, 103, 120, 121, 122, 123, 124, 125, 133]

下标操作也可以用于更新已有集合(对于那些不可变集合)

list = ['a','x','x','d']
list[1..2] = ['b','c']
assert list == ['a','b','c','d']

值得注意的是负数也是被允许的，表示从集合后面提取元素：你可以使用负数来表示从尾开始操作list，array，String等：

text = "nice cheese gromit!"
x = text[-1]
assert x == "!"

同样地，如果你使用一个反向区间(起点下标大于终点下标),结果也会是反的。

text = "nice cheese gromit!"
name = text[3..1]
assert name == "eci"

ConfigSlurper是用来读配置文件的工具类，通常是Grooy脚本格式的配置文件。类似于Java里的*.properties文件。ConfigSlurper允许点操作符，除此之外，还允许闭包操作配置值和一些对象类型

def config = new ConfigSlurper().parse('''
app.date = new Date() （1）
app.age = 42
app { （2）
name = "Test${42}"
}
''')

assert config.app.date instanceof Date

assert config.app.age == 42

assert config.app.name == 'Test42'

（1）使用点操作符

（2）使用闭包来代替点操作符

从上面的例子可以看到，parse方法可以用来返回groovy.util.ConfigObject实例，ConfigObject是一种特别的java.util.Map实现。既可以用于返回配置值，也可以返回一个不为null的新的ConfigObject实例对象

def config = new ConfigSlurper().parse('''
app.date = new Date()
app.age = 42
app.name = "Test${42}"
''')
assert config.test != null //(1)

(1)config.test还没有被实例化因此当被调用的时候将会返回一个ConfigObject

如果点号是配置文件值的一部分，可以使用单引号或双引号将其转义。

def config = new ConfigSlurper().parse('''
app."person.age" = 42
''')

除此之外，ConfigSlurper也支持environments . enviroments方法可以被用来处理闭包实例，它自身也有可能由好几个部分组成。假如说我们想创建一个特定的配置值来给开发环境用，当我们创建一个 ConfigSlurper实例的时候我们可以使用ConfigSlurper(String)构造函数来实现特定环境的配置.

def config = new ConfigSlurper('development').parse('''
environments {
development {
app.port = 8080
}

test {

app.port = 8082

}

production {

app.port = 80

}

}

''')

assert config.app.port == 8080

ConfigSlurper环境变量没有严格遵循任何环境变量名字。取决于特定的ConfigSlurper客户端代码。

enviroments方法是一个那只方法，但是registerConditionalBlock方法可以用于注册其他方法名字，并且可以是enviroments名字。

def slurper = new ConfigSlurper()
slurper.registerConditionalBlock('myProject', 'developers') (1)

myProject {

developers {

sendMail = false

}

}

''')

assert !config.sendMail

(1)一旦一个新的块注册了，ConfigSlurper可以编码它

因为Java集成原因，toProperties方法可以用于将ConfigObject对象转换到 java.util.Properties对象。然后可以将其存在*.properties文本文件中。注意，在新建一个Properties实例的时候配置值将会转换为String类型实例。

def config = new ConfigSlurper().parse('''
app.date = new Date()
app.age = 42
app {
name = "Test${42}"
}
''')

assert properties."app.date" instanceof String

assert properties."app.age" == '42'

assert properties."app.name" == 'Test42'

Expando类可以用于动态创建可拓展对象。尽管它的类名没有采用ExpandoMetaClass。每一个Expando对象代表一个独立的动态的实例，可以在运行时被属性或方法所拓展

def expando = new Expando()
expando.name = 'John'
assert expando.name == 'John'

一个特殊的例子是当一个动态属性注册到一个闭包代码块。一个注册就可以被方法所动态调用：

def expando = new Expando()
expando.toString = { -> 'John' }
expando.say = { String s -> "John says: ${s}" }

assert expando as String == 'John'

assert expando.say('Hi') == 'John says: Hi'

Groovy提供了可观察的lists,maps和sets。每一个都是一个 java.beans.propertyChangeEvnent事件的触发器。当元素被添加，删除，修改就会被触发。注意 PropertyChangeEvent不仅仅当某些事件发生才出发，同时可以保存新旧值。

可能会有类型改变，可观察的集合可能需要更加特别的PropertyChangeEvnet类型。比如当添加一个元素到可观察list触发一个ObservableList.ElementAddedEvent事件。

def event （1）
def listener = {
if (it instanceof ObservableList.ElementEvent) { （2）
event = it
}
} as PropertyChangeListener

def elementAddedEvent = event as ObservableList.ElementAddedEvent

assert elementAddedEvent.changeType == ObservableList.ChangeType.ADDED

assert elementAddedEvent.index == 3

assert elementAddedEvent.oldValue == null

assert elementAddedEvent.newValue == 42

(1)声明一个PropertyChangeEventListener可以捕捉触发事件

(2)ObservableList.ElementEvent和它的相关类型是相对与这个监听器

(3)注册一个监听器

(4)从给定的list创建一个ObservableList

(5)ObservableList.ElementAddedEvent事件的触发器

注意，添加一个元素将会触发两个事件，第一个是ObservableList.ElementAddedEvent 第二个是 PropertyChangeEvent，用来通知监听器这次修改属性的size

ObservableList.ElementClearedEvent 事件类型是另外一个有趣的事件。无论什么时候多个元素被删除，比如当我们调用clear()方法的时候，它将会保存被删除的元素

def event
def listener = {
if (it instanceof ObservableList.ElementEvent) {
event = it
}
} as PropertyChangeListener

def elementClearedEvent = event as ObservableList.ElementClearedEvent

assert elementClearedEvent.values == [1, 2, 3]

assert observable.size() == 0

为了了解整个事件类型，建议读者阅读JavaDoc文档或可观察集合的源码。

这个章节里，ObservableMap和ObservableSet是同一个概念，和我们见过的ObservableList一样。