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安装

下载

release

wget https://github.com/protocolbuffers/protobuf/releases/download/v3.14.0/protobuf-all-3.14.0.tar.gz
tar -zxvf protobuf-all-3.14.0.tar.gz
cd protobuf-3.14.0/
./configure
make
make install

安装protoc-gen-go-grpc插件

go install google.golang.org/grpc/cmd/protoc-gen-go-grpc

问题：

protoc: error while loading shared libraries: libprotoc.so.25: cannot open shared object file: No such file or directory

两种解决方法：

  1. export LD_LIBRARY_PATH=/usr/local/lib
  2. ldconfig

为什么要执行ldconfig
我们通过控制台输出的信息可以知道，Protocol Buffers Libraries的默认安装路径在/usr/local/lib

Libraries have been installed in:
/usr/local/lib

If you ever happen to want to link against installed libraries
in a given directory, LIBDIR, you must either use libtool, and
specify the full pathname of the library, or use the `-LLIBDIR'
flag during linking and do at least one of the following:

  • add LIBDIR to the `LD_LIBRARY_PATH' environment variable
    during execution
  • add LIBDIR to the `LD_RUN_PATH' environment variable
    during linking
  • use the `-Wl,-rpath -Wl,LIBDIR' linker flag
  • have your system administrator add LIBDIR to `/etc/ld.so.conf'

See any operating system documentation about shared libraries for
more information, such as the ld(1) and ld.so(8) manual pages.

而我们安装了一个新的动态链接库，ldconfig一般在系统启动时运行，所以现在会找不到这个lib，因此我们要手动执行ldconfig，让动态链接库为系统所共享，它是一个动态链接库管理命令，这就是ldconfig命令的作用

使用

protoc --go_out=../service  --go_opt paths=source_relative \
--go-grpc_out=../service --go-grpc_opt paths=source_relative \
User.proto

语法速学

repeated 切片类型

syntax="proto3";

package service;
option go_package = "gaodongfei.com/service";


import "google/api/annotations.proto";

message ProdResponse{
    int32 prod_stock=1;
}

message QuerySize{
    int32 size=1;
}

message ProdResponseList{
    repeated ProdResponse prodres=1;
}

service ProdService{
    rpc GetProdStockList(QuerySize)returns(ProdResponseList){}
}

生成

type ProdResponseList struct {
	state         protoimpl.MessageState
	sizeCache     protoimpl.SizeCache
	unknownFields protoimpl.UnknownFields

	Prodres []*ProdResponse `protobuf:"bytes,1,rep,name=prodres,proto3" json:"prodres,omitempty"`
}

enum 枚举类型

enum ProdAreas{
    A=0;
    B=1;
    C=2;
}


message ProdRequest{
    int32 prod_id=1;
    ProdAreas prod_area=2;
}

生成:

ProdAreas
image.png
ProdRequest
image.png

导入外部proto

Model.proto

syntax="proto3";

package service;
option go_package = "gaodongfei.com/service";


message ProdModel{
    int32 prod_id=1;
    string prod_name=2;
    float prod_price=3;
}

Prod.proto

如果两文件 go package 相同则直接使用 ProdModel

import "Model.proto";

生成命令

protoc   --go_out=plugins=grpc:../service \
				 --go_opt  paths=source_relative \
         *.proto

日期类型

Model.proto

import "google/protobuf/timestamp.proto";

message OrderMain{
    int32 order_id=1;
    string order_no=2;
    int32 user_id=3;
    float order_money=4;
    google.protobuf.Timestamp order_time=5;
}

赋值

import (
	"github.com/golang/protobuf/ptypes/timestamp"
  "time"	
)	OrderMain{OrderId:1,OrderTime:&timestamp.Timestamp{Seconds:time.Now().Unix()}}

Oneof

如果你有一组字段，同时最多允许这一组中的一个字段出现，就可以使用Oneof定义这一组字段，这有点Union的意思，但是Oneof允许你设置零各值。

因为proto3没有办法区分正常的值是否是设置了还是取得缺省值(比如int64类型字段，如果它的值是0，你无法判断数据是否包含这个字段，因为0几可能是数据中设置的值，也可能是这个字段的零值)，所以你可以通过Oneof取得这个功能，因为Oneof有判断字段是否设置的功能。

syntax = "proto3";
package abc;
message OneofMessage {
    oneof test_oneof {
      string name = 4;
      int64 value = 9;
    }
  }

map

map类型需要设置键和值的类型，格式是"map" "<" keyType "," type ">" mapName "=" fieldNumber [ "[" fieldOptions "]"。

message OneofMessage {
    oneof test_oneof {
      string name = 4;
      int64 value = 9;
    }
    map<int64,string> field1 = 1;
}

image.png