上篇文章介绍了如何安装protobuf环境,文章链接如下
【Go】protobuf介绍及安装-CSDN博客
本节介绍protobuf在gRPC中具体如何使用,并编写测试用例
一、Protobuf是如何工作的
.proto文件是protobuf一个重要的文件,它定义了需要序列化数据的结构,当protobuf编译器(protoc)来运行.proto文件时候,编译器将生成所选择的语言的代码,比如你选择go语言,那么就会将.proto转换成对应的go语言代码,对于go来说,编译器会为每个消息类型生成一个pd.go文件,而C++会生成一个.h文件和一个.cc文件。
使用protobuf的3个步骤是:
1. 在.proto文件中定义消息格式。
2. 用protobuf编译器编译.proto文件。
3. 用C++/Java/go等对应的protobuf API来写或者读消息。
二、Protobuf代码测试
在开始代码编写与测试之前,把官网的链接分享给大家,这个看完可以避坑,尤其是版本,示例代码,proto文件格式等。
工具安装及demo测试:Quick start | Go | gRPC
1.定义proto文件
syntax="proto3";
option go_package="./;student"; //关于最后生成的go文件是处在哪个目录哪个包中,.代表在当前目录生成,student代表了生成的go文件的包名是student
service DemoService {
rpc Sender(StudentRequest) returns (StudentResponse){}
}
message StudentRequest {
string Id = 1;
}
message StudentResponse {
string result =1;
}
message Student {
int64 Id = 1; //id
string Name =2; //姓名
string No =3; //学号
}
2.生成代码
进入proto文件所在目录,cd ~/sourceCode/go/goproject01/src/day34/grpc/proto
<1>执行protoc --go_out=. student.proto
protoc --go_out=. student.proto
执行后发现proto目录生成了一个文件:student.pb.go
<2>执行protoc --go-grpc_out=. student.proto,发现命令执行报错如下
cd ~/sourceCode/go/goproject01/src/day34/grpc/proto
protoc --go-grpc_out=. student.proto
protoc-gen-go-grpc: program not found or is not executable
Please specify a program using absolute path or make sure the program is available in your PATH system variable
--go-grpc_out: protoc-gen-go-grpc: Plugin failed with status code 1.
执行报错,发现没有安装protoc-gen-go-grpc,需要安装一下
先执行go get
go get google.golang.org/grpc/cmd/protoc-gen-go-grpc
go: downloading google.golang.org/grpc v1.59.0
go: downloading google.golang.org/grpc/cmd/protoc-gen-go-grpc v1.3.0
go: downloading google.golang.org/protobuf v1.28.1
go: added google.golang.org/grpc/cmd/protoc-gen-go-grpc v1.3.0
go: added google.golang.org/protobuf v1.28.1
再执行go install
go install google.golang.org/grpc/cmd/protoc-gen-go-grpc
执行完在$GOBIN目录下生成protoc-gen-go-grpc,源码对应在pkg下
再次执行protoc --go-grpc_out=. student.proto
protoc --go-grpc_out=. student.proto
执行后会在当前目录生成一文件:student_grpc.pb.go
<3>执行go mod tidy
打开文件发现依赖的包没有导入,会报错,需要执行一下最小化导入包依赖
go mod tidy
go: finding module for package google.golang.org/grpc
go: finding module for package google.golang.org/grpc/status
go: finding module for package google.golang.org/grpc/codes
go: found google.golang.org/grpc in google.golang.org/grpc v1.59.0
go: found google.golang.org/grpc/codes in google.golang.org/grpc v1.59.0
go: found google.golang.org/grpc/status in google.golang.org/grpc v1.59.0
go: downloading google.golang.org/genproto v0.0.0-20230822172742-b8732ec3820d
go: downloading golang.org/x/text v0.12.0
执行后生成的代码编译通过,不再报错。
3.编写Server端程序
在server包下创建server.go文件
package main
import (
"context"
"encoding/json"
"errors"
"google.golang.org/grpc"
"google.golang.org/grpc/keepalive"
student "goproject01/day34/grpc/proto"
"log"
"net"
"strconv"
"time"
)
// grpc生成源码后多了一个方法mustEmbedUnimplementedDemoServiceServer
// 这个方法首字母小写不允许重载,自定义实现却没法实现该方法,解决方法如下
/**
1,生成代码时候使用选项:
protoc --go_out=. **--go-grpc_opt=require_unimplemented_servers=false** --go-grpc_out=. proto/*.proto
This works, but your binary will fail to compile if you add methods to your service(s) and regenerate/recompile.
That is why we have the embedding requirement by default. We recommend against using this option.
We recommend against using this option(不推荐使用此选项)
2,使用内嵌的结构体定义
// server is used to implement helloworld.GreeterServer.
type server struct{
// Embed the unimplemented server
helloworld.UnimplementedGreeterServer
}
*/
type MyDemeServiceImpl struct {
student.UnimplementedDemoServiceServer
}
func (ds *MyDemeServiceImpl) Sender(ctx context.Context, in *student.StudentRequest) (*student.StudentResponse, error) {
return handSendMessage(ctx, in)
}
func main() {
//绑定9091端口
listener, err := net.Listen("tcp", ":10005")
if err != nil {
log.Fatalf("bingding port:9091 error:%v", err)
}
//注册服务
//这个连接最大的空闲时间,超过就释放,解决proxy等到网络问题(不通知grpc的client和server)
/**
func NewGrpcServer(opts ...grpc.ServerOption) *grpc.Server {
var options []grpc.ServerOption
options = append(options,
grpc.KeepaliveParams(keepalive.ServerParameters{
Time: 10 * time.Second, // wait time before ping if no activity
Timeout: 20 * time.Second, // ping timeout
}),
grpc.KeepaliveEnforcementPolicy(keepalive.EnforcementPolicy{
MinTime: 60 * time.Second, // min time a client should wait before sending a ping
PermitWithoutStream: true,
}),
grpc.MaxRecvMsgSize(Max_Message_Size),
grpc.MaxSendMsgSize(Max_Message_Size),
)
for _, opt := range opts {
if opt != nil {
options = append(options, opt)
}
}
return grpc.NewServer(options...)
}
*/
option1 := grpc.KeepaliveParams(keepalive.ServerParameters{MaxConnectionIdle: 5 * time.Minute})
option2 := grpc.MaxSendMsgSize(409600) //400kB
option3 := grpc.MaxRecvMsgSize(409600)
grpcServer := grpc.NewServer(option1, option2, option3)
//impliServer := student.UnimplementedDemoServiceServer{}
var impliServer = &MyDemeServiceImpl{}
student.RegisterDemoServiceServer(grpcServer, impliServer)
log.Printf("server listening at %v", listener.Addr())
/*
错误的写成http了,导致排查半天
err = http.Serve(listener, nil)
if err != nil {
log.Fatalf("http serve fail:%v", err)
}*/
if err := grpcServer.Serve(listener); err != nil {
panic("error building server: " + err.Error())
}
}
func handSendMessage(ctx context.Context, req *student.StudentRequest) (*student.StudentResponse, error) {
log.Println("receive param=", req.GetId())
//模拟根据id查询student对象并构建一个student实例
sid := req.GetId()
if sid == "" {
log.Println("request param id is null")
return nil, errors.New("request param id is null")
}
resp := &student.StudentResponse{}
sidInt64, err := strconv.ParseInt(sid, 10, 64)
if err != nil {
log.Printf("sid:%s covert to int64 error", sid)
return nil, errors.New("sid covert to int64 error")
}
//通过proto进行序列化对象,和原始json以及easyJson使用方法类似
s := &student.Student{Name: "xiaoliu", No: "10001", Id: sidInt64}
//bytes, errs := proto.Marshal(s) //需要一个指针类型对象
bytes, errs := json.Marshal(s)
if errs != nil {
log.Println("student obj convert to json error")
return nil, errors.New("student obj convert to json error")
}
resp.Result = bytes
log.Println("返回客户端序列化字符串:", string(bytes))
return resp, nil
}
4.编写客户端程序
package main
import (
"context"
"flag"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials/insecure"
student "goproject01/day34/grpc/proto"
"log"
"time"
)
const (
defaultName = "world"
defaultId = "10001"
)
var (
address = flag.String("address", "localhost:10005", "the address connect to ")
name = flag.String("name", defaultName, " name to great")
id = flag.String("id", defaultId, "id send to server")
)
func main() {
flag.Parse()
connection, err := grpc.Dial(*address, grpc.WithTransportCredentials(insecure.NewCredentials()))
if err != nil {
log.Fatalf("connect localhost:9091 fail:%v\n", err)
}
defer connection.Close()
client := student.NewDemoServiceClient(connection)
ctx, cancel := context.WithTimeout(context.Background(), time.Second*3)
defer cancel()
resp, errs := client.Sender(ctx, &student.StudentRequest{Id: *id})
if errs != nil {
log.Fatalf("client call server Sender method fail:%v\n", errs)
}
//获取StudentResponse result的内容
rst := string(resp.GetResult())
log.Println("rpc returns result:", rst)
}
5.代码测试
<1>启动服务端程序
go run server.go
//启动后打开服务端端口,等待客户端连接日志
2023/12/04 18:24:17 server listening at [::]:10005
//启动后接收客户端的参数打印
2023/12/04 18:24:25 receive param= 10001
2023/12/04 18:24:25 返回客户端序列化字符串: {"Id":10001,"Name":"xiaoliu","No":"10001"}
<2>运行客户端程序
go run client.go
首次执行发现报错如下:
rpc error: code = Unavailable desc = connection error: desc = "error reading server preface: http2: frame too large"
错误解决:自己误把grpc协议写为http,修改代码即可:
/*
错误的写成http了,导致排查半天
err = http.Serve(listener, nil)
if err != nil {
log.Fatalf("http serve fail:%v", err)
}*/
if err := grpcServer.Serve(listener); err != nil {
panic("error building server: " + err.Error())
}
再次执行报错如下:
2023/12/04 18:09:55 client call server Sender method fail:rpc error: code = Internal desc = grpc: error while marshaling: string field contains invalid UTF-8
错误解决:需要修改student.proto文件中StudentResponse的result字段为bytes类型,用来支持utf-8字符。将student.proto文件修改如下:上面的server.go,client.go最终以这个proto文件为准。
syntax="proto3";
option go_package="./;student"; //关于最后生成的go文件是处在哪个目录哪个包中,.代表在当前目录生成,student代表了生成的go文件的包名是student
service DemoService {
rpc Sender(StudentRequest) returns (StudentResponse){}
}
message StudentRequest {
string Id = 1;
}
message StudentResponse {
bytes result =1; //涉及到utf-8编码的字符需要使用bytes类型
}
message Student {
int64 Id = 1;
string Name =2;
string No =3;
}
修改后运行客户端程序:
调用服务端获取序列化的结果如下
go run client.go
2023/12/04 18:24:25 rpc returns result: {"Id":10001,"Name":"xiaoliu","No":"10001"}