7

我正在阅读这里的 alchemy-API 文档：

http://www.alchemyapi.com/api/image-tagging/image.html

他们说图像必须是 URI 编码的……这到底是什么意思？

这是否意味着将图像转换为 base64 字符串，然后将其传递给请求？

我已经尝试过了，但收到 http 414 错误 - 请求 URI 太大。

这是我发出请求的代码：

    @IBAction func analyzeImage(sender: UIButton) {

    var imageData = UIImagePNGRepresentation(mainImage.image)
    let base64ImageString = imageData.base64EncodedStringWithOptions(.allZeros)
    let requestString = ENDPOINT+"?apikey="+API_KEY+"&image="+base64ImageString+"&outputMode=json"


    let url = NSURL(string: requestString)
    let task = NSURLSession.sharedSession().dataTaskWithURL(url!) {(data, response, error) in
        println(NSString(data: data, encoding: NSUTF8StringEncoding))
    }

    task.resume()
}

编辑：我考虑了 Dijkgraaf 的建议，即使用 POST 请求而不是 GET 来解决 URI 长度问题。我正在使用 Alamofire 库来执行此操作。这是我的代码：

@IBAction func analyzeImage(sender: UIButton) {

    var imageData = UIImagePNGRepresentation(mainImage.image)
    let base64ImageString = imageData.base64EncodedStringWithOptions(.allZeros)

    let params = [
        "apikey" : API_KEY,
        "image"  : base64ImageString,
        "outputMode" : "json"]

    var manager = Manager.sharedInstance
    //Passing all the headers you want!
    manager.session.configuration.HTTPAdditionalHeaders = [
        "Content-Type": "application/x-www-form-urlencoded"
    ]
    manager.request(.POST, ENDPOINT, parameters:params, encoding: .URL)
        .response { (request, response, data, error) in
            println(request)
            println(response)
            println(error)
    }
}

但是，当我尝试此操作时，出现“无法分析：下游问题”错误。

这是控制台输出：

<NSMutableURLRequest: 0x1742040c0> { URL: http://access.alchemyapi.com/calls/image/ImageGetRankedImageKeywords }
Optional(<NSHTTPURLResponse: 0x17082c1e0> { URL: http://access.alchemyapi.com/calls/image/ImageGetRankedImageKeywords } { status code: 200, headers {
    "Access-Control-Allow-Origin" = "*";
    "Cache-Control" = "no-cache";
    Connection = "keep-alive";
    "Content-Length" = 326;
    "Content-Type" = "application/json";
    Date = "Mon, 08 Jun 2015 05:59:22 GMT";
    Server = nginx;
    "X-AlchemyAPI-CurrentVersion" = "12.15";
    "X-AlchemyAPI-Error-Msg" = "cannot-analyze:downstream-issue";
    "X-AlchemyAPI-Key" = [API KEY HIDDEN];
    "X-AlchemyAPI-Params" = "sentiment=0&knowledgeGraph=0&detectedLanguage=unknown&submitLanguage=detect";
    "X-AlchemyAPI-Status" = ERROR;
    "X-AlchemyAPI-Total-Transactions" = 0;
} })
nil

不知道出了什么问题，但 Alchemy 文档确实指出 POST 请求应该将“Content-Type”标头设置为“application/x-www-form-urlencoded”，无论如何这似乎都不会发生我试着设置。这可能是问题吗？

编辑：我尝试只发布原始图像数据，再次按照 Dijkgraaf 的建议：

    @IBAction func analyzeImage(sender: UIButton) {

    var imageData = UIImagePNGRepresentation(mainImage.image)
    //let base64ImageString = imageData.base64EncodedStringWithOptions(.allZeros)
    var request = HTTPTask()
    request.requestSerializer = HTTPRequestSerializer()
    request.requestSerializer.headers["Content-Type"] = "application/x-www-form-urlencoded"
    let params: Dictionary<String,AnyObject> = [
        "apikey" : API_KEY,
        "imagePostMode" : "raw",
        "image" : imageData,
        "outputMode" : "json"]
    request.POST(ENDPOINT, parameters: params, completionHandler: {(response: HTTPResponse) in
        println(response.headers)
    })

}

但我仍然再次遇到相同的无法分析下游问题错误。

4

2 回答 2

5

使用 imagePostMode raw 时，需要将图像数据作为 POST 请求的主体发送，参数应包含在端点 URL 中（例如 ENDPOINT="http://access.alchemyapi.com/calls/image/ ImageGetRankedImageKeywords?apikey=API_KEY&outputMode=json&imagePostMode=raw")。我没有使用过 Swift，所以我不知道最好的方法，但这与你所期望的有点不同。

于 2015-06-11T14:01:15.653 回答
2

下面的代码对我有用。

    let image = UIImage(named: "your-image.png")
    getImageTag(image!)

func getImageTag(image:UIImage){
        let apiKey = "xxx-xxx-xxx-xxx-xxx"
        let url = "https://gateway-a.watsonplatform.net/calls/image/ImageGetRankedImageKeywords?imagePostMode=raw&outputMode=json&apikey=" + apiKey
        let myURL = NSURL(string: url)!
        let request = NSMutableURLRequest(URL: myURL)
        request.HTTPMethod = "POST"
        request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
        let imageData = UIImagePNGRepresentation(image)

        request.HTTPBody = imageData!
        let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
        data, response, error in

            // Your completion handler code here
            if let error = error {
                print("error: \(error)")
            }
            print(response)
            print(NSString(data: data!, encoding: NSUTF8StringEncoding))
        }
    task.resume()
}

您还可以通过 curl 命令测试图像标记请求，如下所示。

 curl --data-binary @your_image.png "https://gateway-a.watsonplatform.net/calls/image/ImageGetRankedImageKeywords?imagePostMode=raw&apikey=d3a529b15ac9ebe550a51006815xxxxxx"
于 2015-11-30T13:26:02.240 回答