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go-common/middleware/language.go
2025-12-07 10:32:36 +08:00

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package middleware
import (
"context"
"net/http"
"strings"
)
// LanguageKey context中存储语言的key
type languageKey struct{}
// LanguageHeaderName 语言请求头名称
const LanguageHeaderName = "X-Language"
// AcceptLanguageHeaderName Accept-Language 请求头名称
const AcceptLanguageHeaderName = "Accept-Language"
// DefaultLanguage 默认语言
const DefaultLanguage = "zh-CN"
// GetLanguageFromContext 从context中获取语言
func GetLanguageFromContext(ctx context.Context) string {
if lang, ok := ctx.Value(languageKey{}).(string); ok && lang != "" {
return lang
}
return DefaultLanguage
}
// Language 语言处理中间件
// 从请求头 X-Language 或 Accept-Language 读取语言信息,如果未传递则使用默认语言 zh-CN
// 语言信息会存储到context中可以通过 GetLanguageFromContext 获取
func Language(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// 1. 优先从 X-Language 请求头获取(显式指定)
lang := r.Header.Get(LanguageHeaderName)
// 2. 如果未设置,从 Accept-Language 请求头解析
if lang == "" {
acceptLang := r.Header.Get(AcceptLanguageHeaderName)
if acceptLang != "" {
lang = parseAcceptLanguage(acceptLang)
}
}
// 3. 如果都未设置,使用默认语言
if lang == "" {
lang = DefaultLanguage
}
// 将语言存储到context中
ctx := context.WithValue(r.Context(), languageKey{}, lang)
next.ServeHTTP(w, r.WithContext(ctx))
})
}
// LanguageWithDefault 语言处理中间件(可自定义默认语言)
// defaultLanguage: 默认语言,如果未指定则使用 zh-CN
func LanguageWithDefault(defaultLanguage string) func(http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// 1. 优先从 X-Language 请求头获取(显式指定)
lang := r.Header.Get(LanguageHeaderName)
// 2. 如果未设置,从 Accept-Language 请求头解析
if lang == "" {
acceptLang := r.Header.Get(AcceptLanguageHeaderName)
if acceptLang != "" {
lang = parseAcceptLanguage(acceptLang)
}
}
// 3. 如果都未设置,使用指定的默认语言
if lang == "" {
lang = defaultLanguage
}
// 将语言存储到context中
ctx := context.WithValue(r.Context(), languageKey{}, lang)
next.ServeHTTP(w, r.WithContext(ctx))
})
}
}
// parseAcceptLanguage 解析 Accept-Language 请求头
// 返回第一个语言代码(去掉权重信息)
func parseAcceptLanguage(acceptLang string) string {
if acceptLang == "" {
return ""
}
// 分割语言列表
parts := strings.Split(acceptLang, ",")
if len(parts) == 0 {
return ""
}
// 取第一个语言代码,去掉权重信息(如 ";q=0.9"
firstLang := strings.Split(parts[0], ";")[0]
firstLang = strings.TrimSpace(firstLang)
return firstLang
}