项目中使用protobuf 3.0

protocol buffer从3.0 原生的compiler支持c++,Java,Python,Go,Ruby,JavaNano,JavaScript,Objective-C,C#,PHP这篇文章作为上一篇文章的补充，简单记录下一些变化。

protobuf的开源地址为：https://github.com/google/protobuf

protocol compiler下载地址为：https://github.com/google/protobuf/releases

官方定义message类型的例子：

syntax="proto3"

message SearchRequest{

　　string query=1;

　　int32 page_number=2;

　　int32 result_per_page=3;

}

..proto文件的第一行指定使用proto3的语法。

特定语言的声明使用option关键定和选项名

option java_package="com.example.tutorial";//定义生成的java包

option java_outer_classname="AddressBookProtos";//定义java类名

option csharp_namespace="Google.Protobuf.Examples.AddressBook";//定义c#的命名空间

变化

1.字段前取消了required和optional两个关键字，目前可用的只有repeated关键字。

2.不可以现设置默认值了。

　　a.string默认为空串

　　b.枚举默认为第一个枚举定义的第一个值。并且必须是0

　　c.bytes默认为空bytes

　　d.bool默认为false

　　e.数字类型默认为0

3.类型对应表

.proto Type	Notes	C++ Type	Java Type	Python Type[2]	Go Type	Ruby Type	C# Type	PHP Type
double		double	double	float	float64	Float	double	float
float		float	float	float	float32	Float	float	float
int32	Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint32 instead.	int32	int	int	int32	Fixnum or Bignum (as required)	int	integer
int64	Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint64 instead.	int64	long	int/long[3]	int64	Bignum	long	integer/string[5]
uint32	Uses variable-length encoding.	uint32	int[1]	int/long[3]	uint32	Fixnum or Bignum (as required)	uint	integer
uint64	Uses variable-length encoding.	uint64	long[1]	int/long[3]	uint64	Bignum	ulong	integer/string[5]
sint32	Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int32s.	int32	int	int	int32	Fixnum or Bignum (as required)	int	integer
sint64	Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int64s.	int64	long	int/long[3]	int64	Bignum	long	integer/string[5]
fixed32	Always four bytes. More efficient than uint32 if values are often greater than 228.	uint32	int[1]	int	uint32	Fixnum or Bignum (as required)	uint	integer
fixed64	Always eight bytes. More efficient than uint64 if values are often greater than 256.	uint64	long[1]	int/long[3]	uint64	Bignum	ulong	integer/string[5]
sfixed32	Always four bytes.	int32	int	int	int32	Fixnum or Bignum (as required)	int	integer
sfixed64	Always eight bytes.	int64	long	int/long[3]	int64	Bignum	long	integer/string[5]
bool		bool	boolean	bool	bool	TrueClass/FalseClass	bool	boolean
string	A string must always contain UTF-8 encoded or 7-bit ASCII text.	string	String	str/unicode[4]	string	String (UTF-8)	string	string
bytes	May contain any arbitrary sequence of bytes.	string	ByteString	str	[]byte	String (ASCII-8BIT)	ByteString	string

proto代码编译

语法：

protoc --proto_path=IMPORT_PATH --cpp_out=DST_DIR --java_out=DST_DIR --python_out=DST_DIR --go_out=DST_DIR --ruby_out=DST_DIR --javanano_out=DST_DIR --objc_out=DST_DIR --csharp_out=DST_DIR path/to/file.proto

--proto_path 当proto文件中使用import时指定的导入文件的位置

--cpp_out c++输出目录

--java_out java输出目录

--python_out

--go_out

--ruby_out ruby输出目录

--objc_out oc输出目录

--csharp_out c#输出目录

path/to/file.proto为要编译的proto文件

使用

proto内容：

syntax="proto3";

option java_package="com.ztimage";
option java_outer_classname="WebUI";
option csharp_namespace="ZTImage.WebUI";
message SearchRequest{
string query=1;
int32 page_number=2;
int32 result_per_page=3;
}

执行命令：protoc --csharp_out d:/programs/protoc/bin WebUI.proto

生成代码：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Google.Protobuf;

namespace ZTImage.WebUI
{
class Program
{
static void Main(string[] args)
{
SearchRequest request = new SearchRequest() {
Query="age>0 and age <18",
PageNumber=1,
ResultPerPage=50
};

using (var output = File.Create("mr.dat"))
{
request.WriteTo(output);
}

SearchRequest sr = null;
using (var input = File.OpenRead("mr.dat"))
{
sr = SearchRequest.Parser.ParseFrom(input);
}

Console.WriteLine("Query:{0},PageNumber:{1},ResultPerPage:{2}",sr.Query,sr.PageNumber,sr.ResultPerPage);
Console.ReadKey();

}
}
}

View Code
结果：

Query:age>0 and age <18,PageNumber:1,ResultPerPage:50

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