protobuf与json互相转换

Java

http://code.google.com/p/protobuf-java-format/

maven

<dependency>
<groupId>com.googlecode.protobuf-java-format</groupId>
<artifactId>protobuf-java-format</artifactId>
<version>1.2</version>
</dependency>

从protobuf转json

Message someProto =SomeProto.getDefaultInstance();
String jsonFormat =JsonFormat.printToString(someProto);

从json转protobuf

Message.Builder builder =SomeProto.newBuilder();
String jsonFormat = _load json document from a source_;
JsonFormat.merge(jsonFormat, builder);

C++

https://github.com/shramov/json2pb

 

Python

https://github.com/NextTuesday/py-pb-converters

导入模块pbjson.py即可使用。

ps. 原始模块的pb2json函数会自动过滤protobuf中字段值为空的数据。根据需要可注释掉过滤代码。

 pbjson .py:

import simplejson
	from google.protobuf.descriptor import FieldDescriptor as FD
	class ConvertException(Exception):
	pass
	def dict2pb(cls, adict, strict=False):
	"""
	Takes a class representing the ProtoBuf Message and fills it with data from
	the dict.
	"""
	obj = cls()
	for field in obj.DESCRIPTOR.fields:
	if not field.label == field.LABEL_REQUIRED:
	continue
	if not field.has_default_value:
	continue
	if not field.name in adict:
	raise ConvertException('Field "%s" missing from descriptor dictionary.'
	% field.name)
	field_names = set([field.name for field in obj.DESCRIPTOR.fields])
	if strict:
	for key in adict.keys():
	if key not in field_names:
	raise ConvertException(
	'Key "%s" can not be mapped to field in %s class.'
	% (key, type(obj)))
	for field in obj.DESCRIPTOR.fields:
	if not field.name in adict:
	continue
	msg_type = field.message_type
	if field.label == FD.LABEL_REPEATED:
	if field.type == FD.TYPE_MESSAGE:
	for sub_dict in adict[field.name]:
	item = getattr(obj, field.name).add()
	item.CopyFrom(dict2pb(msg_type._concrete_class, sub_dict))
	else:
	map(getattr(obj, field.name).append, adict[field.name])
	else:
	if field.type == FD.TYPE_MESSAGE:
	value = dict2pb(msg_type._concrete_class, adict[field.name])
	getattr(obj, field.name).CopyFrom(value)
	else:
	setattr(obj, field.name, adict[field.name])
	return obj
	def pb2dict(obj):
	"""
	Takes a ProtoBuf Message obj and convertes it to a dict.
	"""
	adict = {}
	if not obj.IsInitialized():
	return None
	for field in obj.DESCRIPTOR.fields:
	if not getattr(obj, field.name):
	continue
	if not field.label == FD.LABEL_REPEATED:
	if not field.type == FD.TYPE_MESSAGE:
	adict[field.name] = getattr(obj, field.name)
	else:
	value = pb2dict(getattr(obj, field.name))
	if value:
	adict[field.name] = value
	else:
	if field.type == FD.TYPE_MESSAGE:
	adict[field.name] =
	[pb2dict(v) for v in getattr(obj, field.name)]
	else:
	adict[field.name] = [v for v in getattr(obj, field.name)]
	return adict
	def json2pb(cls, json, strict=False):
	"""
	Takes a class representing the Protobuf Message and fills it with data from
	the json string.
	"""
	return dict2pb(cls, simplejson.loads(json), strict)
	def pb2json(obj):
	"""
	Takes a ProtoBuf Message obj and convertes it to a json string.
	"""
	return simplejson.dumps(pb2dict(obj), sort_keys=True, indent=4)

json2pb   

 在功能测试或集成测试中，用json造输入数据，然后moc测试脚本将json转化为protobuf发送给被测试模块或服务，是非常常见的功能测试手段。
        如果测试脚本用Python来写的话，一般的做法是用的Python调用json模块中函数解析json文件，然后新建protobuf对象，依次填写各字段，然后发送出去。
        当然如果愿意造上面的轮子也没关系，如果想偷懒也是可行的，pbjson.py脚本就为你干这事提供了温床，下面会介绍这个过程：
1、造json文件，内容如下：
        #vi testjson2pb.json
        {
            "name":"scq",
            "age":30,
            "work_unit":"taobao",
            "class_mate":[
                {
                    "name":"jim",
                    "age":30
                }
            ]
        }

2、造protobuf文件，内容如下：
        #vi testjson2pb.proto
        //class mate
        package json2pb;
        message PersonInfo {
            //my name
            required string name = 1;
            //my age
            optional int32 age = 2;
            //my work unit
            optional string work_unit = 3;
            message ClassMate {
                //name
                optional string name = 1;
                //age
                optional uint32 age = 2;
            }
            repeated ClassMate class_mate = 4;
        }

3、生成protobuf对应python文件：
        #protoc -I=. --python_out=. testjson2pb.proto
        testjson2pb_pb2.py

4、编写测试例子，具体如下：
        #vi testjson2pb.py
        -------------------------------------------------------------------------------------------------
        #!/usr/bin/env python
        # coding=utf-8

        import sys
        import logging
        import os
        import time
        import string
        import pbjson
        import simplejson
        import testjson2pb_pb2

        def main():
            f = file("testjson2pb.json")
            s = simplejson.load(f)
            f.close
            t = pbjson.dict2pb(testjson2pb_pb2.PersonInfo, s)
            print t

        if __name__  ==  "__main__":
            main()

5、执行脚本，结果如下：
        #python testjson2pb.py
        
        是不是很简单啊，自从有了这个脚本，再用不用担心人肉从json生成protobuf的问题了。
        
      

原文链接:http://blog.chinaunix.net/uid-27714502-id-4067350.html