json.dump() 与　json.dumps()使用方法如下：

# -*- coding:utf-8 -*-
# ! ./usr/bin/env python

import json
jsonpath = 'test.json'

data = {
  "carDark": {
    "name": "CarDark",
    "image_files": [
      "0001.jpg",
      "0002.jpg",
      "0003.jpg",
      "0004.jpg",
      "0005.jpg",
    ],
    "init_rect": [
      73,
      126,
      29,
      23
    ],
    }
}

# one line show
data1 = json.dumps(data)

# multi lines show as dict format
data2 = json.dumps(data, indent=2)　# indent 表示缩进

# write to json file , one line show
with open(jsonpath, 'w') as f:
  json.dump(data, f)

# write to json file , multi lines show as dict format
with open(jsonpath, 'w') as f:
  json.dump(data, f, indent=2)

print(data1)
print(data2)

输出：

第一个print输出：

{"carDark": {"image_files": ["0001.jpg", "0002.jpg", "0003.jpg", "0004.jpg", "0005.jpg"], "init_rect": [73, 126, 29, 23], "name": "CarDark"}}

第二个print输出：

{
  "carDark": {
    "image_files": [
      "0001.jpg", 
      "0002.jpg", 
      "0003.jpg", 
      "0004.jpg", 
      "0005.jpg"
    ], 
    "init_rect": [
      73, 
      126, 
      29, 
      23
    ], 
    "name": "CarDark"
  }
}