使用gin-swagger出现Failed to fetch. Possible Reasons:CORS Network Failure URL scheme must be “http” or “https” for CORS request 解决方案

原因：跨域问题导致

解决方法：

1. 添加Cors中间件，代码如下

func Cors() gin.HandlerFunc {
	return func(c *gin.Context) {
		method := c.Request.Method
		origin := c.Request.Header.Get("Origin")
		var headerKeys []string
		for k, _ := range c.Request.Header {
			headerKeys = append(headerKeys, k)
		}
		headerStr := strings.Join(headerKeys, ", ")
		if headerStr != "" {
			headerStr = fmt.Sprintf("access-control-allow-origin, access-control-allow-headers, %s", headerStr)
		} else {
			headerStr = "access-control-allow-origin, access-control-allow-headers"
		}
		if origin != "" {
			c.Writer.Header().Set("Access-Control-Allow-Origin", "*")
			c.Header("Access-Control-Allow-Origin", "*")                                       // 这是允许访问所有域
			c.Header("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE,UPDATE") //服务器支持的所有跨域请求的方法,为了避免浏览次请求的多次'预检'请求
			//  header的类型
			c.Header("Access-Control-Allow-Headers", "Authorization, Content-Length, X-CSRF-Token, Token,session,X_Requested_With,Accept, Origin, Host, Connection, Accept-Encoding, Accept-Language,DNT, X-CustomHeader, Keep-Alive, User-Agent, X-Requested-With, If-Modified-Since, Cache-Control, Content-Type, Pragma")
			//              允许跨域设置                                                                                                      可以返回其他子段
			c.Header("Access-Control-Expose-Headers", "Content-Length, Access-Control-Allow-Origin, Access-Control-Allow-Headers,Cache-Control,Content-Language,Content-Type,Expires,Last-Modified,Pragma,FooBar") // 跨域关键设置 让浏览器可以解析
			c.Header("Access-Control-Max-Age", "172800")                                                                                                                                                           // 缓存请求信息 单位为秒
			c.Header("Access-Control-Allow-Credentials", "false")                                                                                                                                                  //  跨域请求是否需要带cookie信息 默认设置为true
			c.Set("content-type", "application/json")                                                                                                                                                              // 设置返回格式是json
		}

		//放行所有OPTIONS方法
		//if method == "OPTIONS" {
		//    c.JSON(http.StatusOK, "Options Request!")
		//}
		if method == "OPTIONS" {
			c.AbortWithStatus(204)
			return
		}
		// 处理请求
		c.Next() //  处理请求
	}
}

2. 在路由注册界面引入Cors中间件即可

r := gin.New()
	r.Use(middelwares.Cors())