常见的媒体类型
ALL = '*/*'
APPLICATION_ATOM_XML = 'application/atom+xml'
APPLICATION_FORM_URLENCODED = 'application/x-www-form-urlencoded'
APPLICATION_JSON = 'application/json'
APPLICATION_JSON_UTF8 = 'application/json;charset=utf-8'
APPLICATION_OCTET_STREAM = 'application/octet-stream'
APPLICATION_PDF = 'application/pdf'
APPLICATION_PROBLEM_JSON = 'application/problem+json'
APPLICATION_PROBLEM_XML = 'application/problem+xml'
APPLICATION_RSS_XML = 'application/rss+xml'
APPLICATION_STREAM_JSON = 'application/stream+json'
APPLICATION_XHTML_XML = 'application/xhtml+xml'
APPLICATION_XML = 'application/xml'
IMAGE_JPEG = 'image/jpeg'
IMAGE_APNG = 'image/apng'
IMAGE_PNG = 'image/png'
IMAGE_GIF = 'image/gif'
IMAGE_WEBP = 'image/webp'
IMAGE_ICON = 'image/x-icon'
MULTIPART_FORM_DATA = 'multipart/form-data'
TEXT_EVENT_STREAM = 'text/event-stream'
TEXT_HTML = 'text/html'
TEXT_MARKDOWN = 'text/markdown'
TEXT_PLAIN = 'text/plain'
TEXT_XML = 'text/xml'
GRPC = 'application/grpc'
GRPC_PROTO = 'application/grpc+proto'
GRPC_JSON = 'application/grpc+json'