可以在缓存条件里设置Expires Header

internal/nodes/http_request_cache.go

@@ -241,7 +241,7 @@ func (this *HTTPRequest) doCacheRead() (shouldStop bool) {
 	// 这里强制设置Last-Modified，如果先前源站设置了Last-Modified，将会被覆盖，避免因为源站的Last-Modified导致源站返回304 Not Modified
 	var modifiedTime = ""
 	if lastModifiedAt > 0 {
-		modifiedTime = time.Unix(lastModifiedAt, 0).Format("Mon, 02 Jan 2006 15:04:05 GMT")
+		modifiedTime = time.Unix(utils.GMTUnixTime(lastModifiedAt), 0).Format("Mon, 02 Jan 2006 15:04:05") + " GMT"
 		respHeader.Set("Last-Modified", modifiedTime)
 	}
 
@@ -268,6 +268,7 @@ func (this *HTTPRequest) doCacheRead() (shouldStop bool) {
 	}
 
 	this.processResponseHeaders(reader.Status())
+	this.addExpiresHeader(reader.ExpiresAt())
 
 	// 输出Body
 	if this.RawReq.Method == http.MethodHead {
@@ -441,3 +442,19 @@ func (this *HTTPRequest) doCacheRead() (shouldStop bool) {
 
 	return true
 }
+
+// 设置Expires Header
+func (this *HTTPRequest) addExpiresHeader(expiresAt int64) {
+	if this.cacheRef.ExpiresTime != nil && this.cacheRef.ExpiresTime.IsPrior && this.cacheRef.ExpiresTime.IsOn {
+		if this.cacheRef.ExpiresTime.Overwrite || len(this.writer.Header().Get("Expires")) == 0 {
+			if this.cacheRef.ExpiresTime.AutoCalculate {
+				this.writer.Header().Set("Expires", time.Unix(utils.GMTUnixTime(expiresAt), 0).Format("Mon, 2 Jan 2006 15:04:05")+" GMT")
+			} else if this.cacheRef.ExpiresTime.Duration != nil {
+				var duration = this.cacheRef.ExpiresTime.Duration.Duration()
+				if duration > 0 {
+					this.writer.Header().Set("Expires", utils.GMTTime(time.Now().Add(duration)).Format("Mon, 2 Jan 2006 15:04:05")+" GMT")
+				}
+			}
+		}
+	}
+}

internal/utils/time.go

@@ -27,3 +27,15 @@ func UnixTime() int64 {
 func UnixTimeMilli() int64 {
 	return unixTimeMilli
 }
+
+// GMTUnixTime 计算GMT时间戳
+func GMTUnixTime(timestamp int64) int64 {
+	_, offset := time.Now().Zone()
+	return timestamp - int64(offset)
+}
+
+// GMTTime 计算GMT时间
+func GMTTime(t time.Time) time.Time {
+	_, offset := time.Now().Zone()
+	return t.Add(-time.Duration(offset) * time.Second)
+}

internal/utils/time_test.go

@@ -11,3 +11,11 @@ func TestUnixTime(t *testing.T) {
 		time.Sleep(1 * time.Second)
 	}
 }
+
+func TestGMTUnixTime(t *testing.T) {
+	t.Log(GMTUnixTime(time.Now().Unix()))
+}
+
+func TestGMTTime(t *testing.T) {
+	t.Log(GMTTime(time.Now()))
+}