python自动格式化json文件的方法

class JsonFormatter:  def __init__(self,intend=4,name=""):    self.name=name    self.intend=intend    self.stack=[]    self.obj=None    self.source=self.get_source(name)    self.prepare()  @staticmethod  def json_str(s):    return '"'+s+'"'  @staticmethod  def get_source(name):    with open(name,'r') as f:      return ''.join(f.read().split())  def prepare(self):    try:      self.obj=eval(self.source)    except:      raise Exception('Invalid json string!')  def line_intend(self,level=0):    return '/n'+' '*self.intend*level  def parse_dict(self,obj=None,intend_level=0):    self.stack.append(self.line_intend(intend_level)+'{')    intend_level+=1    for key,value in obj.items():      key=self.json_str(str(key))      self.stack.append(self.line_intend(intend_level)+key+':')      self.parse(value,intend_level)      self.stack.append(',')    self.stack.append(self.line_intend(intend_level-1)+'}')  def parse_list(self,obj=None,intend_level=0):    self.stack.append(self.line_intend(intend_level)+'[')    intend_level+=1    for item in obj:      self.parse(item,intend_level)      self.stack.append(',')    self.stack.append(self.line_intend(intend_level-1)+']')  def parse(self,obj,intend_level=0):    if obj is None:      self.stack.append('null')    elif obj is True:      self.stack.append('true')    elif obj is False:      self.stack.append('false')    elif isinstance(obj,(int,long,float)):      self.stack.append(str(obj))    elif isinstance(obj,str):      self.stack.append(self.json_str(obj))    elif isinstance(obj,(list,tuple)):      self.parse_list(obj,intend_level)    elif isinstance(obj,dict):      self.parse_dict(obj,intend_level)    else:      raise Exception('Invalid json type %s!' % obj)  def render(self):    self.parse(self.obj,0)    res_file='good'+self.name    res=''.join(self.stack)    with open(res_file,'w') as f:      f.write(res)    print resif __name__=="__main__":  jf=JsonFormatter(name="json.txt")  jf.render()