encoding/json: remove proto json (#753)

* remove protojson encoding

config/config.go

@@ -7,9 +7,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/go-kratos/kratos/v2/encoding"
-	// init json encoder
-	_ "github.com/go-kratos/kratos/v2/encoding/json"
 	"github.com/go-kratos/kratos/v2/log"
 )
 
@@ -20,8 +17,6 @@ var (
 	ErrTypeAssert = errors.New("type assert error")
 
 	_ Config = (*config)(nil)
-
-	codec = encoding.GetCodec("json")
 )
 
 // Observer is config observer.
@@ -125,7 +120,7 @@ func (c *config) Scan(v interface{}) error {
 	if err != nil {
 		return err
 	}
-	return codec.Unmarshal(data, v)
+	return unmarshalJSON(data, v)
 }
 
 func (c *config) Watch(key string, o Observer) error {

config/reader.go

@@ -1,10 +1,13 @@
 package config
 
 import (
+	"encoding/json"
 	"fmt"
 	"strings"
 
 	"github.com/imdario/mergo"
+	"google.golang.org/protobuf/encoding/protojson"
+	"google.golang.org/protobuf/proto"
 )
 
 // Reader is config reader.
@@ -71,16 +74,16 @@ func (r *reader) Value(path string) (Value, bool) {
 }
 
 func (r *reader) Source() ([]byte, error) {
-	return codec.Marshal(r.values)
+	return marshalJSON(r.values)
 }
 
 func cloneMap(src map[string]interface{}) (map[string]interface{}, error) {
-	data, err := codec.Marshal(src)
+	data, err := marshalJSON(src)
 	if err != nil {
 		return nil, err
 	}
 	dst := make(map[string]interface{})
-	if err = codec.Unmarshal(data, &dst); err != nil {
+	if err = unmarshalJSON(data, &dst); err != nil {
 		return nil, err
 	}
 	return dst, nil
@@ -104,3 +107,17 @@ func convertMap(src interface{}) interface{} {
 		return src
 	}
 }
+
+func marshalJSON(v interface{}) ([]byte, error) {
+	if m, ok := v.(proto.Message); ok {
+		return protojson.Marshal(m)
+	}
+	return json.Marshal(v)
+}
+
+func unmarshalJSON(data []byte, v interface{}) error {
+	if m, ok := v.(proto.Message); ok {
+		return protojson.Unmarshal(data, m)
+	}
+	return json.Unmarshal(data, v)
+}