Python下将一般对象打印成Json

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　　http://www.cnblogs.com/Colin-Cai/p/12741423.html 

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from functools import reduce
make_json = lambda blanks,obj : \
(lambda t, cut : \
  'null' if obj==None \
  else str(obj) if t in (int,float) \
  else ('true' if obj else 'false') if t==bool \
  else '"%s"'%obj if t==str \
  else '[' + cut(reduce(lambda r,x:r+',\n'+' '*(blanks+2)+make_json(blanks+2,x), obj, '')) \
    + '\n' + ' '*blanks + ']' if t in (list, tuple) \
  else '{' + cut(reduce(lambda r,x:r+',\n'+' '*(blanks+2)+'"%s" : '%x+make_json(blanks+2,obj[x]), \
    sorted(filter(lambda x:type(x)==str,obj.keys())), '')) + '\n' + ' '*blanks + '}' if t==dict \
  else reduce(lambda r,x:r+'%02x'%x, list(map(int, obj)),'"')+'"' if t==bytes \
  else '{' + cut(reduce(lambda r,x:\
    r+',\n'+' '*(blanks+2)+'"%s" : '%x+make_json(blanks+2,obj.__dict__[x]), \
    sorted(filter(lambda x:len(x)<4 or x[:2]!='__' \
      or x[-2:]!='__',obj.__dict__.keys())), '')) + '\n' + ' '*blanks + '}') \
(type(obj), lambda x:x if x=='' else x[1:])

print_json = lambda obj, fprint : fprint(make_json(0, obj))

class class1:
  def __init__(self):
    self.a1 = None
    self.b1 = None
    self.c1 = None

class class2:
  def __init__(self):
    self.a2 = None
    self.b2 = None
    self.c2 = None

class class3:
  def __init__(self):
    self.a3 = None
    self.b3 = None
    self.c3 = None

test_obj = class1()
test_obj.a1 = [1, None, 2.5, class2(), True]
test_obj.a1[3].a2 = [class3(), class3()]
test_obj.a1[3].a2[0].a3 = [1, 2, 3]
test_obj.a1[3].a2[0].b3 = ["test1", "test2"]
test_obj.a1[3].a2[0].c3 = None
test_obj.a1[3].a2[1].a3 = [5, 6, 7]
test_obj.a1[3].a2[1].b3 = ["test3", "test4"]
test_obj.a1[3].a2[1].c3 = [True, False]
test_obj.a1[3].b2 = {"x":1, "y":2}
test_obj.a1[3].c2 = type('', (), {"x":10, "y":20})
test_obj.b1 = 100
test_obj.c1 = "test"
print_json(test_obj, print)

{
  "a1": [
    1,
    null,
    2.5,
    {
      "a2": [
        {
          "a3": [
            1,
            2,
            3
          ],
          "b3": [
            "test1",
            "test2"
          ],
          "c3": null
        },
        {
          "a3": [
            5,
            6,
            7
          ],
          "b3": [
            "test3",
            "test4"
          ],
          "c3": [
            true,
            false
          ]
        }
      ],
      "b2": {
        "x": 1,
        "y": 2
      },
      "c2": {
        "x": 10,
        "y": 20
      }
    },
    true
  ],
  "b1": 100,
  "c1": "test"
}

json_file = open('test_obj.json', 'w')
print_json(test_obj, lambda s:print(s, file=json_file))
json_file.close()