iOS 将 base64 编码的图像上传到 RESTful 服务器时获取 http 400

Question

我是服务器端编程的新手。目前，我正在为 iOS 应用程序开发 RESTful 服务器。

从我的 iOS 应用程序上传图像到 RESTful 服务器。

更新：感谢Codo的建议："You should be more specific about where the error message occurs. My guess is it's when you parse the response in iOS. Your Swift code expects a JSON response. However, on the server side you just send a simple string. That doesn't fit. – Codo"

我添加了一个结果 class，它在服务器端只包含一个字符串类型的消息。（这是一个简单的字符串响应，而不是 class 响应。）我在评论中添加了具体细节。

此外，我添加了一些代码来检查图像数据是否进入 'createImage' 方法。事实证明数据永远不会进入 'createImage' class。问题可能是由于传输图像数据的方式不正确造成的。

这是服务器端的代码：

结果class:

public class Result {
  private String message;

  public String getMessage() {
      return message;
  }

  public void setMessage(String message) {
      this.message = message;
  }

  public Result(String message) {
    super();
    this.message = message;
  }
}

控制器：

@PostMapping(value= "/images") 
public ResponseEntity<Result> createImage(@RequestParam("image") String file,@RequestParam("desc") String  desc){ 

  // check whether or not image data goes here
  try{
        PrintWriter writer = new PrintWriter("D:/cp/check.txt", "UTF-8");
        writer.println("image data is processing");
        writer.close();
  } catch (IOException e) {

  }
  //** file is never created **//

  //** so nothing happens below **/
  if (!file.isEmpty()) {
    try {
      byte[] imageByte= parseBase64Binary(file);

      String directory="D:/cp/" + desc + ".jpg";

      new FileOutputStream(directory).write(imageByte);

      Result result = new Result("You have successfully uploaded ");

      return new ResponseEntity<Result>(result, HttpStatus.OK);
    } catch (Exception e) {
      Result result = new Result("You failed to upload ");
      return new ResponseEntity<Result>(result, HttpStatus.OK);
    }
  } else {
    Result result = new Result("Unable to upload. File is empty.");
    return new ResponseEntity<Result>(result, HttpStatus.OK);
  }
}

这是 iOS 端的代码：

let serviceUrl = URL(string:"http://192.168.0.17:8080/rest/images/")

var request = URLRequest(url: serviceUrl!)

request.httpMethod = "POST"

let image = UIImage(named: "someImage")

let data = UIImagePNGRepresentation(image)

let base64: String! = data?.base64EncodedString()

let body = ["image": base64, "desc": "firstImage"]

do {    
  request.httpBody = try JSONSerialization.data(withJSONObject: body, options: .prettyPrinted)

  let session = URLSession.shared.dataTask(with: request) { 

    (data, response, err) in

    guard err == nil else {
      // Always no error
      print(error.localizedDescription)
      return
    }

    let httpResponse = response as! HTTPURLResponse

    print(httpResponse)
    // <NSHTTPURLResponse: 0x17003bfa0> { URL:  http://192.168.0.17:8080/rest/images/ } 
    // { status code: 400, headers {
    // Connection = close;
    // "Content-Language" = en;
    // "Content-Length" = 1099;
    // "Content-Type" = "text/html;charset=utf-8";
    // Date = "Tue, 27 Dec 2016 23:13:33 GMT";
    // } }

    do {
      let json = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as! Dictionary<String, Any>
      // I pretty sure that parsing data as dictionary is correct because I used same code in many places and they work fine. 

      // code never reaches this line
      print(json.description)

    } catch {
      print(error.localizedDescription)
      // print: 'The data couldn't read because it isn't in the correct format'
      return
    }
  }

  session.resume()

} catch {
  print(error.localizedDescription)
  return
}

我已经做了很多研究，但仍然找不到解决方案。

Answer 1

好的。我自己找出解决办法。我希望它能帮助像我一样的其他初学者。另外，感谢 Codo 的帮助。

首先，我得到“数据无法读取，因为它的格式不正确”的原因是我忘记添加 'Content-Type: application/json' 到header。 iOS 端的代码应该是：

request.serValue("application/json", forHTTPHeaderField: "Content-Type")

其次，在服务器端，我改变

createImage(@RequestParam("image") String file,@RequestParam("desc") String desc)

至：

createImage(@RequestBody Image image)

我使用 @RequestBody 而不是 @RequestParam。 image class 包含两个文件：String file 和 String desc。

就是这样。它对我有用。

iOS 将 base64 编码的图像上传到 RESTful 服务器时获取 http 400

iOS Get http 400 when upload base64 encoded image to a RESTful server

rest

base64

spring

ios

swift