本示例演示如何在Dubbo-go框架中使用context传递和读取附加参数,来实现上下文信息传递。
在客户端中,使用下述方式传递字段, key固定为“attachment”:
ctx := context.Background()
ctx = context.WithValue(ctx, constant.AttachmentKey, map[string]interface{}{
"key1": "user defined value 1",
"key2": "user defined value 2"
})
在服务端中,使用下述方式获取字段, key固定为“attachment”, value的类型为[]string:
attachments := ctx.Value(constant.AttachmentKey).(map[string]interface{})
logger.Infof("Dubbo attachment key1 = %s", value1.([]string)[0])
logger.Infof("Dubbo attachment key2 = %s", value2.([]string)[0])
源文件路径:dubbo-go-sample/context/proto/greet.proto
syntax = "proto3"; package greet; option go_package = "github.com/apache/dubbo-go-samples/context/proto;greet"; message GreetRequest { string name = 1; } message GreetResponse { string greeting = 1; } service GreetService { rpc Greet(GreetRequest) returns (GreetResponse) {} }
源文件路径:dubbo-go-sample/context/go-server/main.go
package main
import (
"context"
"dubbo.apache.org/dubbo-go/v3/common/constant"
_ "dubbo.apache.org/dubbo-go/v3/imports"
"dubbo.apache.org/dubbo-go/v3/protocol"
"dubbo.apache.org/dubbo-go/v3/server"
greet "github.com/apache/dubbo-go-samples/context/proto"
"github.com/dubbogo/gost/log/logger"
)
type GreetTripleServer struct {
}
func (srv *GreetTripleServer) Greet(ctx context.Context, req *greet.GreetRequest) (*greet.GreetResponse, error) {
attachments := ctx.Value(constant.AttachmentKey).(map[string]interface{})
if value1, ok := attachments["key1"]; ok {
logger.Infof("Dubbo attachment key1 = %s", value1.([]string)[0])
}
if value2, ok := attachments["key2"]; ok {
logger.Infof("Dubbo attachment key2 = %s", value2.([]string)[0])
}
resp := &greet.GreetResponse{Greeting: req.Name}
return resp, nil
}
func main() {
srv, err := server.NewServer(
server.WithServerProtocol(
protocol.WithPort(20000),
protocol.WithTriple(),
),
)
if err != nil {
panic(err)
}
if err := greet.RegisterGreetServiceHandler(srv, &GreetTripleServer{}); err != nil {
panic(err)
}
if err := srv.Serve(); err != nil {
logger.Error(err)
}
}
客户端client文件,创建客户端,在context写入变量,发起调用并打印结果
源文件路径:dubbo-go-sample/context/go-client/main.go
package main
import (
"context"
"dubbo.apache.org/dubbo-go/v3/client"
"dubbo.apache.org/dubbo-go/v3/common/constant"
_ "dubbo.apache.org/dubbo-go/v3/imports"
greet "github.com/apache/dubbo-go-samples/context/proto"
"github.com/dubbogo/gost/log/logger"
)
func main() {
cli, err := client.NewClient(
client.WithClientURL("127.0.0.1:20000"),
)
if err != nil {
panic(err)
}
svc, err := greet.NewGreetService(cli)
if err != nil {
panic(err)
}
ctx := context.Background()
ctx = context.WithValue(ctx, constant.AttachmentKey, map[string]interface{}{
"key1": "user defined value 1",
"key2": "user defined value 2",
})
resp, err := svc.Greet(ctx, &greet.GreetRequest{Name: "hello world"})
if err != nil {
logger.Error(err)
}
logger.Infof("Greet response: %s", resp.Greeting)
}
先启动服务端,再启动客户端,可以观察到服务端打印了客户端通过context传递的参数值,说明参数被成功传递并获取
2024-02-26 11:13:14 INFO logger/logging.go:42 Dubbo attachment key1 = [user defined value 1] 2024-02-26 11:13:14 INFO logger/logging.go:42 Dubbo attachment key2 = [user defined value 2]