ajax method to retrieve images as a blob

go 服务端：

就是先把这个图片读出来  然后返回二进制的数据

	byteFile, err := ioutil.ReadFile("."  + "/processed/" + uuidStr+"processed.png")
	if err != nil {
		fmt.Println(err)
	}

	c.Header("Content-Disposition", "attachment; filename=file-name.txt")
	c.Data(http.StatusOK, "application/octet-stream", byteFile)

js 前端获取图片：

function doSomething() {
            //	var videoData = "";
            var fileObj = document.getElementById("fileimage").files[0]; // js 获取文件对象
            var formData = new FormData();
            formData.append("file", fileObj); //上传一个files对象
            // formData.append("参数", "参数1"); //若需要上传的多个参数
            // formData.append("参数", "参数2");
            var url = "http://127.0.0.1:8000/upload/histogram";
            $.ajax({
                url: url,
                // dataType:"text",
                // dataType: "json",
                type: "post",
                data: formData,
                processData : false, //不处理发送的数据
                contentType: false, //不设置Content-Type请求头
                xhrFields:{
                    responseType: 'blob'
                },
                success: function(res) {
                    console.log(111)
                    var img = document.getElementById('img-from-local-storage');
                    var url = window.URL || window.webkitURL;
                    img.src = url.createObjectURL(res);

参考文章：

Sending image files from back-end to front-end - JavaScript - The freeCodeCamp Forum