第三十节 DSL中集合

如果要实现这种定义方式呢？（可以有多个地址，类似淘宝的收货地址）

person {
        name = "张三"
        age = 10
        addresses{
            address {
                city = "北京市"
                street = "北三环街道"
                number = 100000
            }
            address {
                city = "北京市"
                street = "北三环街道"
                number = 100000
            }
        }

    }

代码实现：

fun main(args: Array) {


    var p=person {
        name = "张三"
        age = 10
        addresses{
            address {
                city = "北京市"
                street = "北三环街道"
                number = 100000
            }
            address {
                city = "北京市"
                street = "北三环街道"
                number = 100000
            }
        }
    }
    println(p)


}

fun PersonBuilder.addresses(block:ArrayList
.()->Unit)
{
    //需要定义个集合，赋值给personBuilder的addresses
    var list=ArrayList
()
    block.invoke(list)
    this.addresses=list
}

/**
 * 定义address方法
 */
fun ArrayList
.address(block:AddressBuilder.()->Unit)
{
    var addressBuilder=AddressBuilder()
    block.invoke(addressBuilder)
    this.add(Address(addressBuilder.city,addressBuilder.street,addressBuilder.number))
}
/**
 * 首先定义一个方法person，这个返回定义好的Person对象
 */
fun person(block:PersonBuilder.()->Unit):Person
{
    var personBuilder=PersonBuilder()
    block.invoke(personBuilder)
    return Person(personBuilder.name,personBuilder.age,personBuilder.addresses)
}


/**
 * 我们直接定义成data类型，便于打印
 * 城市、街道、街道号
 */
data class Address(val city:String?,val street:String?,val number:Int?)

data class AddressBuilder(var city:String?=null,var street:String?=null,var number:Int?=null)

/**
 * 姓名、年龄、地址
 */
data class Person(val name:String?,val age:Int?,val addresses: ArrayList
?)


data class PersonBuilder(var name:String?=null,var age:Int?=null,var addresses: ArrayList
?=null)

输出：

image.png