javascript – 使用Ajax从Web服务返回JSON而不是XML,而’contentType’是’false’

我做了一个 AJAX调用,将图像文件发送到我的一个Web服务(.asmx)方法.一切都没问题,但问题是Web服务返回 XML而不是 JSON,因为我必须将’contentType’设置为’false’,否则无法发送文件. (如果我将contentType设置为application / json; charset = utf-8,则返回JSON,但我不能这样做,因为我正在发送文件.)

这是我的JavaScript：

function setAvatar(imageFile,successCallback) {
var formData = new FormData();
formData.append("UploadedAvatar",imageFile);
$.ajax({
    type: "POST",url: "/Services/UserService.asmx/SetAvatar",contentType: false,processData: false,dataType: 'json',data: formData,success: function (result) {
        alert(result.d);
        alert(result.d.IsSuccessful);
        if (typeof successCallback === 'function')
            successCallback(result);
    }
});

和Web服务方法：

[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public Result SetAvatar()
{
    HttpPostedFile postedFile = HttpContext.Current.Request.Files["UploadedAvatar"];
    Image avatar = Image.FromStream(postedFile.InputStream,true,true);
    avatar = new Bitmap(avatar,new Size(150,150));
    avatar.Save(Path.Combine(path,$"Avatar-Small.jpg"),System.Drawing.Imaging.ImageFormat.Jpeg);

    return new Result(true,Messages.AvatarSavedSuccessfully);
}

解决方法

在发出期望JSON的请求时设置Accept标头

$.ajax({
    type: "POST",headers: { //SET ACCEPT HEADER
        Accept : "application/json; charset=utf-8",},success: function (result) {
        alert(result.d);
        alert(result.d.IsSuccessful);
        if (typeof successCallback === 'function')
            successCallback(result);
    }
});

在服务器端,使用Json.Net可以序列化结果

[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public string SetAvatar() {
    HttpPostedFile postedFile = HttpContext.Current.Request.Files["UploadedAvatar"];
    Image avatar = Image.FromStream(postedFile.InputStream,System.Drawing.Imaging.ImageFormat.Jpeg);

    var result = new Result(true,Messages.AvatarSavedSuccessfully);
    return JsonConvert.SerializeObject(result);
}

这应该允许响应处于所需类型