• gRPC构建简易微服务
  • 定义消息
  • 生成.go文件
  • 编写服务端
  • 编写客户端
• gRPC API 编写练习
  • optional字段测试

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gRPC构建简易微服务

代码实现查询，客户端向服务端查询用户的信息

定义消息

syntax = "proto3";  
package query;  
  
option go_package = "./querypb";  
  
// 用户查询  
  
message UserRequest {  
  string name = 1;  
}  
message UserResponse {  
  int32 id = 1;  
  string name = 2;  
  int32 age = 3;  
  repeated string hobbies = 4;  
}  
// service定义方法  
  
service UserInfoService {  
  rpc GetUserInfo(UserRequest) returns (UserResponse);  
}

生成.go文件

protoc -I . --go_out=. --go-grpc_out=. ./query.proto

编写服务端

package main

import (
	"context"
	"errors"
	"from-rpc-to-microservice/querypb"
	"log"
	"net"
	"sync"

	"google.golang.org/grpc"
)

var (
	ErrUsernameNotExist = errors.New("用户名不存在")
)

// 1.需要监听
// 2.需要实例化gRPC服务端
// 3.在gRPC上注册微服务
// 4.启动服务端

// 实现服务端

type UserInfoService struct {
	// 今时不同往日, 现在是要手动嵌入这个结构体来继承那个空方法了
	querypb.UnimplementedUserInfoServiceServer
}

func (u UserInfoService) GetUserInfo(ctx context.Context, request *querypb.UserRequest) (*querypb.UserResponse, error) {
	name := request.Name
	if v, exists := users[name]; exists {
		return &v, nil
	} else {
		return nil, ErrUsernameNotExist
	}
}

// 服务端实例
var u = UserInfoService{}

// 模拟数据库
var users = map[string]querypb.UserResponse{
	"Tom": {
		Id:      1,
		Name:    "Tom",
		Hobbies: []string{"coding", "gaming"},
	},
	"Jerry": {
		Id:      2,
		Name:    "Jerry",
		Hobbies: []string{"gaming", "drawing"},
	},
	"Mike": {
		Id:      3,
		Name:    "Mike",
		Hobbies: []string{"coding", "swimming"},
	},
}

func runServer(wg *sync.WaitGroup) {
	defer wg.Done()

	addr := "127.0.0.1:8080"
	listener, err := net.Listen("tcp", addr)
	if err != nil {
		log.Panicf("TCP监听失败: %v", err)
	}
	log.Printf("已占用地址: %s", addr)

	s := grpc.NewServer() // 实例化gRPC Server
	querypb.RegisterUserInfoServiceServer(s, &u)
	if err := s.Serve(listener); err != nil {
		log.Panicf("启动服务失败: %v", err)
	}
}

编写客户端

package main

import (
	"context"
	"from-rpc-to-microservice/querypb"
	"log"
	"sync"

	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
)

// 1.连接服务端
// 2.实例gRPC客户端
// 3.调用

func runClient(wg *sync.WaitGroup) {
	defer wg.Done()

	// grpc.WithInsecure已经被废弃
	// grpc.Dial也被废弃了
	conn, err := grpc.NewClient("127.0.0.1:8080", grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		log.Panicf("连接服务端失败: %v", err)
	}
	defer func() {
		_ = conn.Close()
		log.Printf("已关闭连接")
	}()

	// 实例化客户端
	client := querypb.NewUserInfoServiceClient(conn)
	req := &querypb.UserRequest{
		Name: "Kirk",
	}
	resp, err := client.GetUserInfo(context.Background(), req)
	if err != nil {
		log.Panicf("调用服务端失败: %v", err)
	}
	log.Printf("服务端返回: %v", resp)
}

gRPC API 编写练习

optional字段测试

注

optional: (recommended) An optional field is in one of two possible states:

• the field is set, and contains a value that was explicitly set or parsed from the wire. It will be serialized to the wire.
• the field is unset, and will return the default value. It will not be serialized to the wire.

不传值的时候可以是nil（最好把数据模型里的类型也换成*类型，这样Gorm扫描时可以忽略nil值）；有传值的时候才能被序列化

业务逻辑根据自己需要编写，反正只是测试

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