如何使用 json 上传图片？

Question

我正在尝试上传包含 json 数据的图像。我只是按照 the post 并实现了该机制。但是我收到错误

{ status code: 400, headers {
    "Cache-Control" = "no-cache, no-store, max-age=0, must-revalidate";
    Connection = close;
    "Content-Language" = en;
    "Content-Length" = 1033;
    "Content-Type" = "text/html;charset=utf-8";
    Date = "Wed, 27 Jan 2016 10:44:34 GMT";
    Expires = 0;
    Pragma = "no-cache";
    Server = "Apache-Coyote/1.1";
    "X-Content-Type-Options" = nosniff;
    "X-XSS-Protection" = "1; mode=block";
} }`

下面是完整的 HTTP 请求

Content-Type: multipart/form-data;boundary=Boundary_123456789
Authorization: Basic bihdwbcIUkbcdwjnoNOn
User-Agent: Jersey/2.21.1 (HttpUrlConnection 1.8.0_45)
MIME-Version: 1.0
Host: localhost:8080
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Connection: keep-alive
Content-Length: 3526

--Boundary_123456789
Content-Type: application/json
Content-Disposition: form-data; name="userDTO"

{"id":"id","name":"name","age":23}
--Boundary_123456789
Content-Type: image/png
Content-Disposition: form-data; filename="sample-image2.png"; modification-date="Fri, 22 Jan 2016 04:56:48 GMT"; size=3308; name="file"

‰PNG

<Binary data>

--Boundary_123456789—

下面是我的实现

func addUser(completion: (message: String?, error: String?) -> Void) -> NSURLSessionDataTask {
        // create the request            
        let request = createRequest()

        let task = NSURLSession.sharedSession().dataTaskWithRequest(request) { data, response, error in
            print(response) // 400 Error is printed here
        }
        task.resume()

        return task
    }
func createRequest () -> NSURLRequest {
    let param = [
        "id": "id",
        "name": "name",
        "age": 23]  // build your dictionary however appropriate

    let boundary = generateBoundaryString()

    let url = NSURL(string: SERVERURL)!
    let request = NSMutableURLRequest(URL: url)
    request.HTTPMethod = "POST"
    request.addValue("Basic \(base64LoginString())", forHTTPHeaderField: "Authorization")
    request.setValue("multipart/form-data; boundary=\(boundary)", forHTTPHeaderField: "Content-Type")

    let path1 = NSBundle.mainBundle().pathForResource("userImage", ofType: "png") as String!
    request.HTTPBody = createBodyWithParameters(param, paths: [path1], boundary: boundary)

    return request
}

func createBodyWithParameters(json: [String:AnyObject], paths: [String]?, boundary: String) -> NSData {
    let body = NSMutableData()
    let key = "userDTO"

    body.appendString("--\(boundary)\r\n")
    body.appendString("Content-Type: application/json")
    body.appendString("Content-Disposition: form-data; name=\"\(key)\"\r\n\r\n")
    var requestBody = NSData()

    do {
        requestBody = try NSJSONSerialization.dataWithJSONObject(json, options: NSJSONWritingOptions(rawValue:0))
    } catch (let e) {
        print(e)
    }
    body.appendData(requestBody)
    //body.appendString("\(json)\r\n")

    if paths != nil {
        for path in paths! {
            let url = NSURL(fileURLWithPath: path)
            let data = NSData(contentsOfURL: url)!
            let mimetype = mimeTypeForPath(path)
            let fileName = "sample-image23.png"
            let date = "Fri, 22 Jan 2016 04:56:48 GMT"
            let name = "file"

            body.appendString("--\(boundary)\r\n")
            body.appendString("Content-Type: \(mimetype)\r\n\r\n")
            body.appendString("Content-Disposition: form-data; filename=\"\(fileName)\"; modification-date=\"\(date)\"; size=3308; name=\"\(name)\"\r\n")
            body.appendData(data)
            body.appendString("\r\n")
        }
    }

    body.appendString("--\(boundary)--\r\n")
    return body
}

func generateBoundaryString() -> String {
    return "Boundary-\(NSUUID().UUIDString)"
}

func mimeTypeForPath(path: String) -> String {
    let url = NSURL(fileURLWithPath: path)
    let pathExtension = url.pathExtension

    if let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, pathExtension! as NSString, nil)?.takeRetainedValue() {
        if let mimetype = UTTypeCopyPreferredTagWithClass(uti, kUTTagClassMIMEType)?.takeRetainedValue() {
            return mimetype as String
        }
    }
    return "application/octet-stream";
}

还有扩展名

extension NSMutableData {

    func appendString(string: String) {
        let data = string.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: true)
        appendData(data!)
    }
}

我想我在 json 格式上犯了一些错误。有人可以帮忙吗？谢谢！

Answer 1

此代码段将帮助您使用 POST 方法将 UIImage 文件上传到网络服务。

func uploadImageOne(){
    var imageData = UIImagePNGRepresentation(exampleImageView.image)

    if imageData != nil{
        var request = NSMutableURLRequest(URL: NSURL(string:"Your URL")!)
        var session = NSURLSession.sharedSession()

        request.HTTPMethod = "POST"

        var boundary = NSString(format: "---------------------------14737809831466499882746641449")
        var contentType = NSString(format: "multipart/form-data; boundary=%@",boundary)
      //  println("Content Type \(contentType)")
        request.addValue(contentType, forHTTPHeaderField: "Content-Type")

        var body = NSMutableData.alloc()

        // Title
         body.appendData(NSString(format: "\r\n--%@\r\n",boundary).dataUsingEncoding(NSUTF8StringEncoding)!)
        body.appendData(NSString(format:"Content-Disposition: form-data; name=\"title\"\r\n\r\n").dataUsingEncoding(NSUTF8StringEncoding)!)
        body.appendData("Hello World".dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: true)!)

        // Image
        body.appendData(NSString(format: "\r\n--%@\r\n", boundary).dataUsingEncoding(NSUTF8StringEncoding)!)
        body.appendData(NSString(format:"Content-Disposition: form-data; name=\"profile_img\"; filename=\"img.jpg\"\r\n").dataUsingEncoding(NSUTF8StringEncoding)!)
        body.appendData(NSString(format: "Content-Type: application/octet-stream\r\n\r\n").dataUsingEncoding(NSUTF8StringEncoding)!)
        body.appendData(imageData)
        body.appendData(NSString(format: "\r\n--%@\r\n", boundary).dataUsingEncoding(NSUTF8StringEncoding)!)



        request.HTTPBody = body


        var returnData = NSURLConnection.sendSynchronousRequest(request, returningResponse: nil, error: nil)

        var returnString = NSString(data: returnData!, encoding: NSUTF8StringEncoding)

        println("returnString \(returnString)")

    }


}

Answer 2

看来，上传图片不是你的问题——就我所见，它成功了。你应该意识到，上传图片与JSON无关。相反，以您期望的格式 (JSON) 获得响应可能正是您所寻求的。因此，如果您需要获得 body 为 JSON 的响应，您应该通过设置适当的 Accept header 来明确说明这一点。例如：

Accept: application/json

在代码中：

request.setValue("application/json", forHTTPHeaderField: "Accept")

当你得到响应时，你还应该首先检查响应的状态码，然后是Content-Type header（分别是响应'MIMEType 属性 ) 应符合您的预期：application/json。

如果内容类型不是您所期望的，您也可以尝试额外的 "response serializers" - 每个都适合解析其他 content-types，例如text/plain等等，随你喜欢。

编辑：

服务器响应提示，多部分请求的第二部分格式错误。看看它是如何组成的：

        body.appendString("--\(boundary)\r\n")
        body.appendString("Content-Type: \(mimetype)\r\n\r\n")
        body.appendString("Content-Disposition: form-data; filename='sample-image23.png'; modification-date='Fri, 22 Jan 2016 04:56:48 GMT'; size=3308; name='file'\r\n")
        body.appendData(data)
        body.appendString("\r\n")

现在，仔细观察，我们可以看到第二个 header Content-Type 将用 two CRLF 分隔 - 但还有另一个header 关注。 Headers 应该只与分开 CRLF.

那么，最后一个header必须用两个分隔CRLF.

建议的修复：

        body.appendString("--\(boundary)\r\n")
        body.appendString("Content-Disposition: form-data; filename='sample-image23.png'; modification-date='Fri, 22 Jan 2016 04:56:48 GMT'; size=3308; name='file'\r\n")
        body.appendString("Content-Type: \(mimetype)\r\n\r\n")
        body.appendData(data)
        body.appendString("\r\n")

（编辑：删除了不正确的描述）

编辑 2：

这些行中还缺少一个 CRLF，在这一行之上：

let key = "userDTO"

body.appendString("--\(boundary)\r\n")
body.appendString("Content-Type: application/json")
body.appendString("Content-Disposition: form-data; name=\"\(key)\"\r\n\r\n")

你看到问题了吗？ Content-Type 没有尾随 CRLF!

另请参阅：NSURLRequest Upload Multiple Files

如何使用 json 上传图片？

How to upload an image with json?

ios

swift

multipartform-data

nsurlsession

nsmutableurlrequest