fix: decode jt808 registration plate text

go/vehicle-gateway/internal/protocol/jt808/parser.go

@@ -1,14 +1,17 @@
 package jt808
 
 import (
+	"bytes"
 	"encoding/binary"
 	"encoding/hex"
 	"errors"
 	"fmt"
 	"strings"
 	"time"
+	"unicode/utf8"
 
 	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
+	"golang.org/x/text/encoding/simplifiedchinese"
 )
 
 var (
@@ -318,7 +321,18 @@ func fixedText(data []byte) string {
 }
 
 func freeText(data []byte) string {
-	return strings.TrimRight(strings.TrimSpace(string(data)), "\x00")
+	data = bytes.Trim(data, "\x00 ")
+	if len(data) == 0 {
+		return ""
+	}
+	if utf8.Valid(data) {
+		return string(data)
+	}
+	decoded, err := simplifiedchinese.GBK.NewDecoder().Bytes(data)
+	if err == nil && utf8.Valid(decoded) {
+		return string(decoded)
+	}
+	return strings.ToValidUTF8(string(data), "")
 }
 
 func parseBCDTime(data []byte) time.Time {