Ruby哈希对象

Question

如下面的代码所示，分配h ['1']会影响对象。谁能解释这是怎么发生的？

class Post
  attr_accessor :json_data, :first_name

  def initialize
    @json_data = {'2': 'two'}
    @first_name = 'check'
  end

end

p1 = Post.new
h = p1.json_data
h['1'] = 'one'
p p1

O / P：@json_data = {：“ 2” =>“两个”，“ 1” =>“一个”}，@ first_name =“ jhvhvvjh”