magic_server/apis/middleware/i18n.go

package middleware

import (
	"app/commons/constant"
	"app/commons/services"
	"bufio"
	"bytes"
	"fmt"
	"github.com/gin-gonic/gin"
	"github.com/tidwall/gjson"
	"github.com/tidwall/sjson"
	"net"
	"net/http"
)

func I18n() gin.HandlerFunc {
	return func(ctx *gin.Context) {
		lang := constant.LangeEn // 默认英文
		// postman会覆盖掉language
		if val := ctx.GetHeader(constant.HeaderKeyLang); len(val) > 0 {
			lang = val
		}
		if val := ctx.GetHeader(constant.HeaderKeyLanguage); len(val) > 0 {
			lang = val
		}
		ctx.Set(constant.HeaderKeyLang, lang)
		// 开始处理返回结果
		w := NewResWriter(ctx.Writer)
		ctx.Writer = w
		// 调用下一个中间件
		ctx.Next()
		// 最终输出内容
		defer func() {
			w.Flush()
		}()
		var err error
		// 获取返回结果
		if bodyString := w.Body.String(); len(bodyString) > 0 {
			msg := gjson.Get(bodyString, "msg").String()
			if len(msg) == 0 {
				return
			}
			// 翻译返回码
			key := fmt.Sprintf("%s", msg)
			i18nText := services.GetI18nService().Translate(lang, key)
			bodyString, err = sjson.Set(bodyString, "msg", i18nText)
			if err != nil {
				return
			}
			// 重新写入响应
			w.Body.Reset()
			w.Body.Write([]byte(bodyString))

		}
	}
}

type ResWriter struct {
	Writer  gin.ResponseWriter // the actual ResponseWriter to flush to
	status  int                // the HTTP response code from WriteHeader
	Body    *bytes.Buffer      // the response content body
	Flushed bool
}

func NewResWriter(w gin.ResponseWriter) *ResWriter {
	return &ResWriter{
		Writer: w,
		status: w.Status(),
		Body:   &bytes.Buffer{},
	}
}

func (w *ResWriter) Header() http.Header {
	return w.Writer.Header() // use the actual response header
}

func (w *ResWriter) Write(buf []byte) (int, error) {
	w.Body.Write(buf)
	return len(buf), nil
}

func (w *ResWriter) WriteString(s string) (n int, err error) {
	n, err = w.Write([]byte(s))
	return
}

const (
	noWritten = -1
)

func (w *ResWriter) Written() bool {
	return w.Body.Len() != noWritten
}

func (w *ResWriter) WriteHeader(status int) {
	w.status = status
}

func (w *ResWriter) WriteHeaderNow() {
}

func (w *ResWriter) Status() int {
	return w.status
}

func (w *ResWriter) Size() int {
	return w.Body.Len()
}

func (w *ResWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
	return w.Writer.(http.Hijacker).Hijack()
}

func (w *ResWriter) CloseNotify() <-chan bool {
	return w.Writer.(http.CloseNotifier).CloseNotify()
}

func (w *ResWriter) Pusher() http.Pusher {
	return w.Pusher()
}

func (w *ResWriter) Flush() {
	w.realFlush()
}

func (w *ResWriter) realFlush() {
	if w.Flushed {
		return
	}
	w.Writer.WriteHeader(w.status)
	if w.Body.Len() > 0 {
		_, err := w.Writer.Write(w.Body.Bytes())
		if err != nil {
			panic(err)
		}
		w.Body.Reset()
	}
	w.Flushed = true
}